Journal of Computational & Applied Research in Mechanical Engineering (JCARME)Journal of Computational & Applied Research in Mechanical Engineering (JCARME)
http://jcarme.sru.ac.ir/
Tue, 07 Jul 2020 02:56:33 +0100FeedCreatorJournal of Computational & Applied Research in Mechanical Engineering (JCARME)
http://jcarme.sru.ac.ir/
Feed provided by Journal of Computational & Applied Research in Mechanical Engineering (JCARME). Click to visit.Grasp analysis of a four-fingered robotic hand based on Matlab simmechanics
http://jcarme.sru.ac.ir/article_1033_208.html
The structure of the human hand is a complex design comprising of various bones, joints, tendons, and muscles functioning together in order to produce the desired motion. It becomes a challenging task to develop a robotic hand replicating the capabilities of the human hand. In this paper, the analysis of the four-fingered robotic hand is carried out where the tendon wires and a spring return mechanism is used for the flexion and extension motion of the fingers, respectively. Stable grasping and fine manipulation of different objects are desired from any multi-finger robotic hand. In this regard, it becomes necessary to check the performance of the four-fingered robotic hand. Simulations are performed for the hand to grasp objects of different size and shapes, and the hand model is controlled in a MATLAB environment using the SimMechanics toolbox. Here the Kinematics and Dynamics study of the hand system is carried out by importing the Solidworks model into the SimMechanics. Simulation results demonstrate that the developed hand model is able to grasp objects of varying size and shapes securely.Fri, 31 Jan 2020 20:30:00 +0100Influence of Material and Internal Support on the Natural Frequencies of Thin-Walled ...
http://jcarme.sru.ac.ir/article_1380_0.html
Water storage tanks are amongst the essential infrastructures, and the study of their natural frequencies plays a pivotal role in predicting and detecting dynamic behavior. Therefore, it helps to the uninterrupted operation of an industrial plant and the use of tank water in emergencies. This paper has studied the influence of different shell materials including steel, aluminum, and laminated composites with three types of different fiber orientations, on the natural frequencies of thin-walled aboveground water storage tanks that have pinned boundary conditions at the base. Models investigated in this paper, either the roof is without an internal support structure or else a group of columns and radial beams are used for supporting it. These huge tanks had the height to diameter ratio 0.4, and a water surface at 90% of the height of the tank's cylinder. The thicknesses of the cylindrical shells are tapered. The tanks without internal support included the vibrations that affect the cylinder mode shapes or the roof mode shapes or simultaneously both the cylinder and roof mode shapes. On the other hand, the mode shapes of the tanks with internal support affect predominantly only the cylinder. Among the studied tanks, the third type of composite tanks had the highest rigidity, and the first type of composite tanks had the lowest rigidity. The natural frequencies related to the first modes of vibrations for cylinder and roof shells with a wide range of circumferential wave numbers (n) and an axial half-wave (m) are studied.Mon, 15 Jun 2020 19:30:00 +0100Effects of the asymmetric behavior of the shape memory alloy on nonlinear dynamic responses of ...
http://jcarme.sru.ac.ir/article_1034_208.html
In the present article, the dynamic behavior of sandwich plates with embedded shape memory alloy (SMA) wires is evaluated for two cases wherein (i) the stress-strain curve of the superelastic behavior of the SMA wires is symmetric and (ii) the mentioned curve is non-symmetric. A modified version of Brinson’s constitutive model is proposed and used. The high non-linearity in the behavior stems from the SMA wires embedded in the sandwich plate. In this regard, in addition to the proposed advanced algorithm for the determination of the martensite volume fraction, a Picard iterative solution algorithm is used in conjunction with Newmark’s numerical time integration method for solving the resulting finite element equations. To improve the accuracy of the results, the variation of martensite volume fraction and material properties of individual points of the structure are updated continuously. Therefore, the kinetic equations of the phase transformation of the SMA are coupled with the motion equations, to accurately model the nonlinear behavior of the sandwich plate. For analysis of the thick sandwich plate, a higher-order global-local theory with novel 3D-equilibrium-based corrections is utilized. One of the features of this theory is the estimation capability of the nonlinear in-plane displacement components, and precise assessment of the transverse shear stresses through satisfying the continuity conditions of the shear stresses at the interfaces between layers. Another advantage of the proposed theory in comparison with the conventional approaches is the ability to simulate changes in the core thickness. This is especially important in cases where the core is relatively thick or soft. Fri, 31 Jan 2020 20:30:00 +0100Experimental investigation of surface crack density and recast layer thickness of WEDMed Inconel 825
http://jcarme.sru.ac.ir/article_1372_0.html
The present research attempts to analyze the surface topography of WEDMed Inconel 825 with respect to surface crack density (SCDi) and recast layer thickness (RCLt). Formation of cracks, recast layer and heat-affected zone are the major issues in determining the final performance of WEDM machined sample. In this study, WEDM characteristics viz. pulse on time (Ton), pulse off time (Toff), gap voltage (SV), peak current (IP), wire tension (WT) and wire feed (WF) are optimized for response SCDi and RCLt by response surface methodology. The outcome manifested that the topography of the machined surface becomes more rough at increased value of Ton, IP and SV. RSM emerged as a great tool in the development of a predicted model based on desirability approach and finding optimal parametric combination which results in reduced SCDi and RCLt. At optimum combination of process parameters i.e. 109 machine unit Ton, 36 machine unit Toff, 54 V SV, 120A IP, 9 machine unit WT and 7 m/min WF, the values obtained for SCDi and RCLt were 0.00160 μm/μm2 and 20.991μm respectively with an error of less than 5%.Sun, 07 Jun 2020 19:30:00 +0100Automatic implementation of a new recovery coefficient for Reliable contour milling
http://jcarme.sru.ac.ir/article_889_208.html
In contour milling, to render the machining process more automated with significant productivity without remaining material after machining, a new recovery coefficient was developed. The coefficient was inserted in the computation of contour parallel tool paths to fix the radial depth of cut in the way to ensure an optimized overlap area between the passes in the corners, without residuals. Thus, this parameter, which has been earlier inserted by the user, is now being independent and is implemented automatically from the input data of the contour shape of the pocket. In order to prove the effectiveness of the present approach, a detailed comparison with the classical methods found in the literature we also performed. The results clearly show that the new method removes the residuals efficiently in an automatic way and minimizes the toolpath length respect to the other methods. Furthermore, this proposed approach can easily be worked on the actual machine tool.Fri, 31 Jan 2020 20:30:00 +0100Effect of geometrical parameters on fluid film coefficients in tilting pad journal bearing
http://jcarme.sru.ac.ir/article_1263_0.html
The simplified analytical method has developed to analyze the effect of bearing geometrical parameters, i.e. eccentricity ratio, journal rotation speed, slenderness ratio, bearing radial clearance, pad pivot offset and the number of pads on tilting pad journal bearing (TPJB) properties, i.e. fluid film thickness, fluid film forces and fluid film stiffness and damping coefficients of TPJB. Reynolds equation was solved for each pad to determine fluid film pressure on pads. The infinite short bearing assumption used to determine pressure distribution on pads integrated over the pad surface to find fluid film forces. The pressure distribution and fluid film forces validated with previous researches. Error bars presented to indicate accuracy measurement. The maximum error found was not more than 6 percent corresponding to loaded pads. The percentage error found maximum when the eccentricity ratio is 0.25 while it found a minimum when the eccentricity ratio is 0.62. The Matlab code has been developed for the solution of non-linear equations. Results produced in the form of design curves which compares changes in fluid film properties corresponding to TPJB geometric parameters. The results obtained in this manuscript are applicable in other similar researches to find appropriate and limiting values of fluid film properties at different geometrical and parametric conditions. The generated plots and data are helpful in dynamic analysis to find the value of a specific parameter corresponding to a specific value of fluid film coefficient, which makes an easier selection of suitable numerical integration technique and boundary conditions to avoid non-significant results, which save time and effort in the nonlinear analysis.Mon, 25 May 2020 19:30:00 +0100Numerical analysis of heat transfer enhancement and flow structure of alternating oval tubes by ...
http://jcarme.sru.ac.ir/article_903_208.html
In this research, the convective heat transfers of turbulent water fluid flow in alternating oval tubes is studied using computational fluid dynamics. The purpose of the study is to analyze the heat transfer enhancement and secondary internal flows under different alternate angles. Also, comparing the effect of two schemesfor the domain discretization to be used in the solution variables’ gradients on simulation results is investigated. The secondary flow causes an increase in the numbers of multi-longitudinal vortices (MLV) by changing the angle of pitches. These phenomena permit the cold fluid flow to stream in more paths from center to tube wall and better condition for mixing of fluids. Consequently, the heat transfer enhances by using the alternating oval tubes. However, forming the multi-longitudinal vortices causes an increase in pressure drop. Also, by raising the angle of pitches, the friction factor and the average of Nusselt number are amplified. It is also observed that the average heat transfer coefficient in the transition range is more than other areas. The mean Nussult numbers of this kind of tubes in the angles of 40, 60, 80, and 90 improved 7.77%, 14.6%, 16.93%, and 24.42%, respectively in comparison with the round tube. The performance evaluation criteria (PEC) for all alternating oval tubes under the constant inlet velocity boundary condition indicated that the highest value (PEC=1.09) had been obtained at the lowest Reynolds number (Re=10,000) in the alternating oval tube 90°.Fri, 31 Jan 2020 20:30:00 +0100Solid-phase effects on the performance of a centrifugal slurry pump using computational fluid ...
http://jcarme.sru.ac.ir/article_1230_0.html
The centrifugal slurry pump is the most common slurry flow pump used in mining industries. The pump head and efficiency are affected by the size, concentration, and density of solid particle when these pumps are applied for the control of slurries. Because the suspended solids in the liquid could not well absorb, store, and transmit pressure energy, they cause quite different changes in efficiency and performance curve shape. This study was conducted to investigate the variations of the mentioned factors at different flow rates using a numerical simulation of the centrifugal slurry pump. For this purpose, the 3D turbulent flow was solved by applying Reynolds-Averaged Navier-Stokes (RANS) equations using the Shear Stress Transfer (SST) turbulence model based on Eulerian-Eulerian for 45% to 120% flow rates in CFX software. The accuracy of the numerical solution was investigated by comparing the characteristic curves resulting from the numerical solution with experimental data‏. The obtained results show a satisfactory fitting among the calculated values from the numerical analysis and experimental data to predict pressure and velocity distribution and global performance. Moreover, by simulating the effect of different parameters of the slurry flow, their effect on the characteristic curves of the slurry pump was compared. These results reveal that the numerical solution can efficiently predict the variation trend of the slurry flow parameters.Sat, 16 May 2020 19:30:00 +0100Experimental investigation on constant-speed diesel engine fuelled with biofuel mixtures under ...
http://jcarme.sru.ac.ir/article_921_208.html
The petroleum product has seen a drastic demand in the recent past. Biofuels are the only solution to overcome this power crisis. In the view of sustainable energy development, biodiesel and its additives have become the best options for fossil fuel-based engines. In this work, a biodiesel mix was used to show the possible utilization of different biofuels. An experimental investigation was carried out on a direct-injection constant-speed (Rated speed- 1500 rpm) diesel engine at different injection pressures of 180, 220 and 260 bar with natural aspiration and supercharging modes. The blends of Biodiesel (used cooking oil, with a mix of algae) and diesel fuels are the selected fuel to investigate. At lower injection pressures, brake speciﬁc fuel consumption of the engine was low and further lowered with supercharging operation. With the reduction of injection pressures, brake thermal efﬁciency values are improved, and the same was observed with supercharging. With the rise in injection pressures, NOx emissions increased due to rise in temperature, and unburnt hydrocarbon emissions were slightly increased. The algae biodiesel was used as an additive to increase the stability of biodiesel. The overall observation indicates that a moderate injection pressure of 220 bar is advisable.Fri, 31 Jan 2020 20:30:00 +0100Numerical Study of Transient Behavior and Heat Transfer in a Phase Change Material (PCM) ...
http://jcarme.sru.ac.ir/article_1226_0.html
Phase Change Materials (PCMs) are known to be capable of storing a substantial amount of energy in relatively low volume. Also, since the phase change process occurs in a nearly constant temperature, PCMs are suitable to be used as storage units. The present study focuses on the effect of Heat Transfer Fluid (HTF) flow parameters on heat transfer and melting process of PCM. The numerical results are validated against available experimental data. Then, the numerical study is extended to investigate the impacts of HTF flow parameters such as inlet temperature and mass flow rate. According to the obtained numerical results, the overall performance of the system is enhanced by increasing the inlet parameters of the HTF flow. In addition, the exergy analysis indicated that the stored exergy increases with increasing flow rate and inlet temperature of HTF. On the other hand, the exergy efficiency does not increase monotonically, but it reaches its maximum value in intermediate values of inlet flow rate and temperature.Fri, 08 May 2020 19:30:00 +0100High-velocity impact properties of multi-walled carbon nanotubes/E-glass fiber/epoxy anisogrid ...
http://jcarme.sru.ac.ir/article_922_208.html
This work reports the high-velocity impact response of multiscale anisogrid composite (AGC) panels. The aim of the present study is to evaluate the influence of surface-modified multi-walled carbon nanotubes (S-MWCNTs) at different S-MWCNTs contents (0-0.5 wt.% at an interval of 0.1 wt.%) on the high-velocity impact responses of E-glass/epoxy AGC. Surface modification of MWCNTs is confirmed by Fourier-transform infrared (FTIR) and thermogravimetric (TGA) analyses. AGC panels were fabricated via a manual filament winding technique. E-glass fiber roving and E-glass woven fabric are employed as reinforcing agents in ribs and skin, respectively. The impact test is done on the composite panels by a cylindrical projectile with a conical nose. The results showe that the highest enhancement in the impact characteristics is attributed to the panel containing 0.4 wt.% S-MWCNTs. Based on the analysis of fracture surfaces, enhanced interfacial fiber/matrix bonding is observed for the S-MWCNTs loaded specimen. Furthermore, the incorporation of MWCNTs leads to the reduced damaged area and enhanced tolerance of damage.Fri, 31 Jan 2020 20:30:00 +0100Tomographic reconstruction of isotropic materials using genetic algorithms with ultrasound ...
http://jcarme.sru.ac.ir/article_1225_0.html
Engineering materials and structures have crack-like defects leading to premature failures. Usage of fracture mechanics to assess the structural integrity requires knowledge on the type, location, shape, size, and orientation of the flaws. Tomographic reconstruction is one of the commonly used nondestructive testing methods for flaw characterization. The cross sectional image of the object being tested is obtained through the application of various reconstruction methods that are categorized as either analytical methods or iterative methods. In this work an iterative algorithm that works on the principles of genetic algorithms is developed and used for the reconstruction. The results of simulation studies on the tomographic reconstructions using genetic algorithms for the identification of defects in isotropic materials are discussed in the paper. The solution methodology based on use of genetic algorithms is applied to reconstruct the cross sections of test specimens with different flaw characteristics. Simulated time-of-flight data of ultrasound rays transmitted through the specimen under investigation is used as input to the algorithm. The time-of-flight data is simulated neglecting the bending of ultrasound rays and assuming straight ray paths. Numerical studies performed on several specimens with flaws of known materials but unknown location, size and shape are presented. The number of ultrasonic transmitters and receivers needed for complete scanning of the specimen’s cross section is analyzed and presented. The findings of parametric analysis and sensitivity analysis in order to choose appropriate range of algorithm parameters for performance quality and robustness of the algorithm are presented. Performance of present algorithm with noisy projection data is also discussed.Fri, 08 May 2020 19:30:00 +0100Analytical study of nano-bioconvective flow in a horizontal channel using Adomian decomposition ...
http://jcarme.sru.ac.ir/article_883_208.html
In this paper, the bioconvective nanofluid flow in a horizontal channel was considered. Using the appropriate similarity functions, the partial differential equations of the studied problem resulting from mathematical modeling are reduced to a set of non-linear differential equations. Thereafter, these equations are solved numerically using the fourth order Runge-Kutta method featuring shooting technique and analytically via the Adomian decomposition method (ADM). This study mainly focuses on the effects of several physical parameters such as Reynolds number (Re), thermal parameter (𝛿𝜃), microorganisms density parameter (𝛿s) and nanoparticles concentration (𝛿f) on the velocity, temperature, nanoparticle volume fraction and density of motile microorganisms. It is also demonstrated that the analytical ADM results are in excellent agreement with the numerical solution and those reported in literature, thus justifying the robustness of the adopted Adomian Decomposition Method.Fri, 31 Jan 2020 20:30:00 +0100Simulation of blood flow in the abdominal aorta considering penetration into the organs using ...
http://jcarme.sru.ac.ir/article_1223_0.html
One of the critical limitations of studies on cardiovascular blood flow simulation is to determine outlet boundary conditions accurately. In the present study, for the first time, pore network model is proposed as a useful technique to take into account interaction between blood flow and other body organs. Thus body organs are simulated by pore network model. Thanks to the method, pressure distribution among the porous medium of organ is determined and consequently the required boundary conditions are obtained for the simulation of arterial blood flow. The comparison between permeability resulted from developed model and experimental results shows that the difference is about 3% for the assumption of non-Newtonian blood flow through organ. This indicates the pore network model can accurately simulate velocity and pressure in the organs. Afterwards, a 3D patient-specific abdominal aorta was simulated under the proposed outlet boundary condition. The maximum deviation of predicted pressure from physiological data is 11.14% near the systole instant. Generally, the predicted pressure and velocity profiles are evident that the model can adequately simulate the blood flow through the arteries which feed main organs.Mon, 27 Apr 2020 19:30:00 +0100Numerical study of induction heating by micro / nano magnetic particles in hyperthermia
http://jcarme.sru.ac.ir/article_1022_208.html
Hyperthermia is one of the first applications of nanotechnology in medicine by using micro/nano magnetic particles that act based on the heat of ferric oxide nanoparticles or quantum dots in an external alternating magnetic field. In this study, a two-dimensional model of body and tumor tissues embedded is considered. Initially, the temperature distribution is obtained with respect to tumor properties and without the presence of an electromagnetic field. Then, the effect of the electromagnetic field on the temperature distribution is studied. The results are compared with those of other papers. The results indicate that the use of the electromagnetic field causes a significant rise in the tumor temperature; however, the risk of damage to the healthy tissues surrounding the cancerous tissue seems to be high. Then, the micro/nanoparticles are injected into the tumor tissue to focus energy on cancerous tissue and maximally transfer the heat onto the tissue. The temperature distribution in the state is compared with the case with no nanoparticles and other numerical works. The results demonstrate that with the injection of nanoparticles into the tumor, the maximum temperature location is transferred to the center of the tumor and also increases to 6°C. After determining the temperature distribution in the presence of nanoparticles, the effects of different variables of the problem are studied. According to the obtained results, the increase in the concentration and radius of nanoparticles have a positive effect on the temperature distribution in the tissue; on the other hand, the increase in the frequency and size of the electrodes have a negative effect. The relevant equations are solved numerically using the finite difference method.Fri, 31 Jan 2020 20:30:00 +0100Numerical analysis of microchannel based bio-inspired heat sinks with multiple inlet-outlet ...
http://jcarme.sru.ac.ir/article_1219_0.html
Heat dissipation in electronic circuits is important to maintain their reliability and functionality. In this work micro-channel based bio-inspired flow field models are proposed and numerically analyzed. The proposed flow fields have single to four, inlet-outlet pairs. COMSOL is used to do the numerical analysis. Conjugate heat transfer analysis is done on the quarter sectional models, utilizing bi-axial symmetry of the flow fields to reduce computational cost. Constant heat flux is applied to the base of the proposed heat sinks. The results show that, the thermal and hydraulic resistances of the proposed models are lower than traditional micro-channel arrays. The four inlet-outlet pairs, model shows a thermal resistance of 0.121 to 0.158 C/W at constant Re inlet condition, achieved with a pumping power of 0.102-0.126W. Two and four, inlet-outlet pair models with aspect ratio 8.6 have a thermal resistance of 0.069 and 0.067 C/W, for pumping powers 2.078 and 4.365W respectively. The pressure drop of the proposed models is lower than conventional microchannel arrays.Mon, 20 Apr 2020 19:30:00 +0100Magneto Prandtl nanofluid past a stretching surface with non-linear radiation and chemical reaction
http://jcarme.sru.ac.ir/article_906_208.html
In this article, we examined the behavior of chemical reaction effect on a magnetohydrodynamic Prandtl nanofluid flow due to stretchable sheet. Non-linear thermally radiative term is accounted in energy equation. Constructive transformation is adopted to formulate the ordinary coupled differential equations system. This system of equations is treated numerically through Runge Kutta Fehlberg-45 method based shooing method. The role of physical constraints on liquid velocity, temperature and concentration are discussed through numerical data and plots. Also, the skin friction co-efficient, local Nusselt number and local Sherwood numbers are calculated to study the flow behavior at the wall, which is also presented in tabular form. A comparative analysis is presented with the previous published data in special case for the justification of the present results. The output reveals that for larger values of elastic and Prandtl parameter, the thickness of momentum layer enhanced and the rates of both heat and mass transport reduced. Also, increment of slip parameter decelerated both temperature and concentration filed while nonlinear form thermal radiation rapidly increases the temperature. Fri, 31 Jan 2020 20:30:00 +0100Linear thermal radiation effects on MHD viscoelastic fluid flow through porous moving plate ...
http://jcarme.sru.ac.ir/article_1218_0.html
Due to the presence of rheological flow parameters and viscoelastic properties, non-Newtonian fluid structure is intricate and enticing to investigate. The flow has been made by considering variable temperature and radiation effects for the magnetohydrodynamic viscoelastic liquid past a moving vertical plate in a porous state. First order homogeneous chemical reaction, Soret number, variable temperature and concentration has been taken into account. The leading mathematical proclamation is handled analytically by perturbation strategy. The central aspiration of this work is to explore the consequences of sundry parameters on fluid flow, thermal boundary and concentration profiles. Diagram and tabular trends of the profiles are delineated with apropos parameters. Our sketches illustrate that the velocity profile exposes decelerate scenery with escalating M due to the Lorentz force in the opposite direction of flow. Temperature profile is getting accelerated owing to thermal radiation and concentration distribution is declined by boosting up the chemical reaction and Schmidt number. Diminishing nature of momentum boundary layer with Sc is also portrayed. Furthermore, at the end of this paper the effects of different parameters on skin fricition coefficient and local Nusselt number are investigated.Sun, 12 Apr 2020 19:30:00 +0100Effect of blade profile on the performance characteristics of axial compressor in design condition
http://jcarme.sru.ac.ir/article_907_208.html
The choice of geometrical shape of the blades has a considerable effect on aerodynamic performance and flow characteristics in axial compressors. In this paper, the effects of the blades shape on the aerodynamic design characteristics are investigated based on Streamline Curvature Method (SCM). Initially, the Streamline Curvature Method (SCM) is used for designing a two-stage axial compressor. Comparing the current results with experimental ones indicates good agreement. The first stage of the axial compressor is selected with three different blade profiles. The first case (case I) has the polynomial camber with naca thickness distribution series 6. The second case (case II) has the standard naca profile series 6 and the third case (case III) has the modified standard naca profile series 4. Results reveal that using the standard airfoils in the stators leads to improved flow conditions such as loss coefficient and pressure ratio. On the contrary, this profile selection may cause an increase in the stagger angle that is not favorable. Aerodynamic Design with a polynomial camber line in the rotor demonstrates a better aerodynamic behavior in loss coefficient, pressure ratio and diffusion factor. Whilst the use of such a camber line in the stator leads to the formation of less favorable aerodynamics conditions in comparison to the standard airfoil.Fri, 31 Jan 2020 20:30:00 +0100Research on the Dynamics of a Hydraulic Static-pile-pressing Machine during the Process of ...
http://jcarme.sru.ac.ir/article_1217_0.html
Information about the dynamic loading of a steel structure is important for its static design as well as for an assessment of its fatigue life. In the case of a hydraulic static-pile-pressing machine, these loads are mainly caused by vibrations and load sway, which occurs as a result of the slewing motion of the boom around the vertical axis and from the radial movement of the load’s suspension point. This paper presents a study of the dynamics of a hydraulic static-pile-pressing machine during the process of lifting and slewing a pile using a mounted crane. A six -degree-of-freedom non-linear spatial-dynamic model is employed and a non-linear mathematical model of the machine was formulated. To confirm the mathematical model, a comparison between the measured results and simulation results using the mathematical model shows that the mathematical model is reliable. These results can be used to optimise machine design based on calculations of its dynamics, fatigue, life expectancy and stability from a dynamic point of view.Sun, 12 Apr 2020 19:30:00 +0100Unsteady convective flow for MHD powell-eyring fluid over inclined permeable surface
http://jcarme.sru.ac.ir/article_1054_208.html
The current article has investigated unsteady convective flow for MHD non-Newtonian Powell-Eyring fluid embedded porous medium over inclined permeable stretching sheet. We have pondered the thermophoresis parameter, chemical reaction, variable thermal conductivity, Brownian motion, variable heat source and variable thermal radiation in temperature and concentration profiles. Using similar transformation, the PDEs are converted by couple ODEs and solve by R–K–Fehlberg 4th–5th order method. The physical features of non-dimensional radiation parameter, non-Newtonian fluid parameters, suction /injection parameter, mass Grashof number porosity parameter, temperature ratio parameter, thermal Grashof number, Biot number of temperature and Biot number of concentration have been analyzed by plotting the graphs of graphical representations of momentum, heat, and mass profiles. , and have been analyzed. The transfer rate of temperature is decreased whereas the flow rate offluid grows with an enhancement in (K) and (Gr).The transfer rate of the temperature is distinctly boosted whereas the fluid flow rate is distinctly declined with an enhancement in (M) , (Kp).Fri, 31 Jan 2020 20:30:00 +0100Analysis of Generalized Compressor Characteristic on Surge Phenomena in Axial Compressors
http://jcarme.sru.ac.ir/article_1216_0.html
The paper discusses the effect of compressor characteristic on surge phenomena in axial flow compressors. Specifically, the effect of nonlinearities on the compressor dynamics is analyzed. For this purpose, generalized multiple time scales method is used to parameterize equations in amplitude and frequency explicitly. The pure surge case of the famous Moore-Greitzer model is used as the basis of the study. The compressor characteristic used in the Moore-Greitzer model is generalized to evaluate the effect of the parameters involved. Subsequently, bifurcation theory is used to study the effect of nonlinear dynamics on surge behavior. It has been found that the system exhibits supercritical Hopf bifurcation under specific conditions in which surge manifests as limit cycle oscillations. Key parameters have been identified in the analytical solution which govern the nonlinear dynamic behavior and are responsible for the existence of limit cycle oscillations. Numerical simulations of the Moore-Greitzer model are carried out and are found in good agreement with the analytical solutionFri, 10 Apr 2020 19:30:00 +0100The effect of injection parameters on dimensional accuracy of wax patterns for investment casting
http://jcarme.sru.ac.ir/article_1000_208.html
Thermal expansion and hot deformation are two phenomena causing dimensional errors in investment casting. This error occurs in dimensions between the die and wax pattern. Therefore, the wax's thermo-physical and thermo-mechanical properties, the metal die features, and the process parameters affect the dimensions of the wax pattern. Some important effective process parameters are the injection temperature, die temperature, and holding time. In this paper, the effect of injection parameters on the dimensional accuracy of the wax model created by a metallic die is studied. The Taguchi formulation based on the design of experiments is applied to obtain the optimum condition in achieving the best dimensional accuracy. The studied specimen has an “F” shape with 10 dimensions. The root mean square (RMS) of dimensional differences is considered for accuracy analysis. The results show that if the injection temperature, injection pressure, and holding time are considered as 80oC, 20 bar, and 2.5 min, respectively, the best accuracy may be achieved.Fri, 31 Jan 2020 20:30:00 +0100Analysis of chemical reaction and thermophoresis on MHD flow near the accelerated vertical ...
http://jcarme.sru.ac.ir/article_1188_0.html
This study analyses the combined effect of chemical reaction and Soret number on MHD flow of a viscous and incompressible fluid near the exponentially accelerated infinite vertical plate in a rotating system. The fluid under consideration is electrically conducting and the medium is porous. A set of dimensionless governing equations of the model is obtained. As the equations are linear, an exact solution is derived by using Laplace technique. The effect of flow parameters on the concentration, temperature and velocity are discussed through graphs. It is noticed that the components of the velocity in both the directions can be increased by increasing the Soret number. And the velocities can be reduced by increasing the chemical reaction parameter. Tables depict the numerical values of the rate of change of momentum, concentration and temperature. Applications of the study arise in the field like solar plasma and planetary fluid dynamics systems, rotating MHD generators etc.Mon, 27 Jan 2020 20:30:00 +0100Design and construction of fruit solar drier for rural settlements
http://jcarme.sru.ac.ir/article_1119_208.html
This research focuses on the need for preserving fruits in rural areas to prevent waste. The solar drier is made of vital chambers i.e. the concentrator chamber (that harvests the solar irradiance), the transport pipe (that transports the heat generated by convection) and hanger chamber (where the fruits are placed). The temperature within the concentrator chamber and hanger chamber was monitored. The design allowed heat transfer by convection from the collector to the chamber at an efficiency of 92 %. The design allowed the temperature build up in the solar collector to be transported faster through hanger chamber with the help of incorporated detachable low power dc fan. This arrangement makes the dryer to either operate in the natural convection dryer mode (without the fan) or as a forced convection dryer (with the fan attached). It is observed that the forced convection provided higher air in-flow and hence greater drying capability. However, regions with moderate precipitation may have challenges of delayed fruit drying and growth of microorganism over the surfaces of the dried fruit. Fri, 31 Jan 2020 20:30:00 +0100Analytical study of induced magnetic field and heat source on chemically radiative MHD ...
http://jcarme.sru.ac.ir/article_1183_0.html
Due to their position in various industrial applications, convective fluid flow structure is intricate and enticing to investigate. Here the flow has been made by considering multitudinous apropos parameters like induced magnetic factor, heat source and viscous dissipation effects for the mixed convective chemically radiative fluid from a vertical surface. The frame work of mathematical pattern is conferred with in the circumstances of a system of ordinary differential equations under felicitous legislation.The governed mathematical statement is handled analytically by perturbation strategy. Diagrams and numerical values of the profiles are delineated with apropos parameters. Our sketches illustrate that the induced magnetic field is perceived to be downward with intensification in magnetic parameter. Temperature profile is accelerated by rising thermal radiation and concentration distribution is decelerated by enhancing the chemical reaction and Schmidt number. Propelled by the precursory research, the intrusion here is to scrutinize the repercussion of induced magnetic factor on viscous stream because of vertical surface.Mon, 13 Jan 2020 20:30:00 +0100Numerical investigation of upward air-water annular, slug and bubbly flow regimes
http://jcarme.sru.ac.ir/article_1023_208.html
In this paper, numerical investigation of upward two phase flow of air-water has been studied. Different conditions of flow regimes including annular, wispy annular, slug, churn and bubbly are simulated based on Hewitt and Roberts map, and a good agreement between the experimental data of the map and the numerical simulation has been observed. Accordingly, a proper CFD model in CFD software of Fluent with the required User Defined Function (UDF) has been obtained to simulate two phase flows of fluids with large density ratio in vertical tubes. The simulation is carried out with the volume of fluid (VOF) method and piecewise interface calculation (PLIC) algorithm for tracking the interface for the annular, wispy annular, churn and slug flow regimes and drift flux model for bubbly with proper selection of computational cell and time step sizes. Furthermore, water and air momentum fluxes have been changed and the changes to the flow patterns are studied.Fri, 31 Jan 2020 20:30:00 +0100Numerical analysis of photovoltaic power generation in different locations of Bangladesh
http://jcarme.sru.ac.ir/article_1179_0.html
Photovoltaic (PV) module is one of the most useful, sustainable and non-harmful product in the field of renewable energy. It offers longer service period for least maintenance cost. The elements of PV are abrasive, easy for designing, and their structure like stand-alone technique give production from micro to mega-power level. A 3D numerical system of PV module has been build up and solved applying FEM technique based software COMSOL Multiphysics in this article. The average solar irradiation and optimum tilt angle for six divisions (Dhaka, Chittagong, Rajshahi, Khulna, Barishal and Sylhet) in Bangladesh have been calculated. The effects of solar radiation, angle of inclination, ambient temperature, and partial shading on temperature of solar cell, electrical power and PV module's electrical efficiency have been investigated. It has been observed from the results that the greatest value of electrical power 15.14 W is found in Rajshahi for solar radiation 209 W/m2. The highest electrical efficiency is found as 12.85% in Sylhet at irradiation level of 189 W/m2. For every 1° increase of inclination angle, electrical power and electrical efficiency level devalue by 0.06 W and 0.05%, respectively. Results also show that the efficiency level is decreased from 14.66 to 11.32% due to partial shading area from 0 to 40%. PV module's electrical power and electrical efficiency reduce approximately 0.01 W and 0.01%, respectively due to every 1°C addition of solar cell temperature.Sun, 15 Dec 2019 20:30:00 +0100MHD Casson fluid flow through a vertical plate
http://jcarme.sru.ac.ir/article_1101_208.html
In this study, effects of numerous physical quantities like dissipation, thermal radiation, and induced magnetic field on magnetohydrodynamic Casson fluid flow through a vertical plate is addressed. The non-dimensional multivariable governing equations are solved numerically by by means of Runge-Kutta method along with shooting technique. The behavior of velocity, temperature and induced magnetic fields for different physical aspects is discussed through graphical illustrations. The influence of physical constants like Casson fluid (β), Magnetic parameter Μ, Soret number Sc, Prandtl number Pr, Magnetic Prandtl number etc., on induced magnetic field, temperature and velocity is analyzed. Interesting observation of this study is that the effect of velocity distribution obeys the physical nature of well-known Newtonian and all other Non-Newtonian fluids. Fri, 31 Jan 2020 20:30:00 +0100Investigation of temperature jump and slip effects on nanofluid treatment inside a vertical ...
http://jcarme.sru.ac.ir/article_1178_0.html
In the present work, the study of alumina-water nanofluid heat transfer between two concentric vertical cylinders has been done by modified Buongiorno’s model (BM) to examine the impacts of temperature jump and slip velocity boundary conditions for a wide range of Knudsen number. Runge-Kutta-Fehlberg method as a standard integration scheme along with a shooting method, has been chosen for solving nonlinear ordinary differential equations (ODEs) along with boundary conditions. The main concentration of this paper focuses on the temperature jump since the slip velocity has been extensively studied in many studies. The presence of temperature jump boundary condition by varying Knudsen number was considered to investigate the effects of the bulk mean nanoparticle volume fraction ϕB, mixed convection parameter Nr, buoyancy parameter Ng, and heat flux ratio ε on the total dimensionless heat transfer coefficient HTC and the dimensionless pressure gradient Ndp. The obtained results indicate that temperature jump boundary condition plays a pivotal role in temperature profile, heat transfer coefficient and pressure drop; for instance, the negligence of temperature jump near walls causes to undervalue heat transfer coefficient in continuum flow regime and overestimate it in slip flow regime.Sun, 15 Dec 2019 20:30:00 +0100Computational evaluation of the homogeneity of composites processed by accumulative roll ...
http://jcarme.sru.ac.ir/article_923_208.html
A new computational method based on MATLAB was used to study the effect of different parameters on the homogeneity of composites produced by a severe plastic deformation technique known as accumulative roll bonding. For a higher number of passes, the degree of particle agglomeration and clustering decreased, and an appreciable homogeneity was obtained in both longitudinal and transverse directions. Moreover, it was found that the rolling temperature does not have any tangible effect on the distribution of particles. Furthermore, it was shown that while faster homogeneity can be obtained in the transverse direction by a cross accumulative roll bonding process, there is not any significant difference between homogeneity of particle distribution between this technique and other routes. In fact, after enough passes, the homogeneity level in all processing methods tends to a common value. Finally, the evolution of the mechanical properties of the composites sheets based on the work hardening, composite strengthening, grain refinement at high accumulative roll bonding cycles, and bonding between particles and the matrix was also briefly discussed.Fri, 31 Jan 2020 20:30:00 +0100The Effect of Turbulence Model on Predicting the Development and Progression of Coronary Artery ...
http://jcarme.sru.ac.ir/article_1177_0.html
A severe case of stenosis in coronary arteries results in turbulence in the blood flow which may lead to the formation or progression of atherosclerosis. This study investigated the turbulent blood flow in a coronary artery with rigid walls, as well as 80% single and double stenoses on blood flow. A finite element-based software package, ADINA 8.8, was employed to model the blood flow. The hemodynamic parameters of blood, such as the Oscillatory Shear Index (OSI) and the Mean Wall Shear Stress (Mean WSS) were obtained by both k-ε and k-ω turbulence models and then compared. According to the results, the negative pressure predicted by the k-ω turbulence model was several times greater than that by the k-ε turbulence model for both single and double stenoses. This, in turn, leads to the collapse of artery walls and irreparable injuries to the downstream extremity. Furthermore, the k-ω model predicted a larger reverse flow region in the post-stenotic region. In other words, the k-ω turbulence model predicts a larger part of the post-stenotic region to be prone to disease and the k-ε turbulence model predicted a higher rate of plaque growth. Moreover, the k-ω model predicted a much more intense reverse flow region than the k-ε model, which itself can lead to blood pressure disease.Fri, 13 Dec 2019 20:30:00 +0100Effectiveness of alumina nanofluid on slotting end milling performance of SKD 11 tool steel
http://jcarme.sru.ac.ir/article_1021_208.html
SKD 11 tool steel is among the most popular metals in mold industries for making different kinds of cold work molds and dies with high accuracy and long service life. The demand for higher quality, lower manufacturing costs, particularly the environmentally friendly characteristics, have provided the stimuli for manufacturers and researchers to find alternative solutions. An excellent media is formed in the cutting zone by using MQL nanofluids in order to enhance the thermal conductivity and tribological characteristics; therefore, improving the machining performance. The formation of the lubricating film as well as the rolling action of nanoparticles in contact zones has gained much attention in the machining field. In this research work, the application of MQL Al2O3 nanofluids with vegetable oils and emulsion 5% is developed for slotting end milling of SKD 11 steel using normal HSS tool. The cutting forces, tool wear, tool life, and surface roughness are investigated to evaluate the effectiveness of MQL nanofluid on cutting performance. The experimental results reveal that the cutting forces and cutting temperature decrease and the surface quality and tool life enhance. Furthermore, the improvement of the thermal conductivity of nanofluids is proven when compared to pure fluids. Due to the rise of viscosity and thermal conductivity, the soybean oil-based nanofluid, which is almost inherently nontoxic, gives superior lubricating and cooling properties suitable for MQL application compared to emulsion-based nanofluids. The novel environmental friendly technology definitely brings out many technological and economic benefits in machining practice. Fri, 31 Jan 2020 20:30:00 +0100A systematic approach for a better thermal management of photovoltaic systems- A review
http://jcarme.sru.ac.ir/article_1176_0.html
Solar energy is the highly recognized energy source, capable of fulfilling the world’s future energy demands. The solar photovoltaic technology involves the unmediated transformation of sunlight into electricity. A little fraction is converted into electricity and the remaining gets exhausted as unused heat. This results in an increase in the operating temperature of the PV Panel. The conversion efficiency and the life span of the photovoltaic panel are affected by an increase in working temperature. Hence, an appropriate cooling technique is essentially required for maintaining the operating temperature of the module within the limits prescribed so as to obtain higher electrical yield and increased lifespan. The objective of this paper is to present a summary of the various cooling techniques used to enhance the performance of PV panels, namely air cooling - free and forced, water spray cooling, cooling by phase change materials, heat pipe cooling, liquid immersion cooling and forced water circulation. Several research articles are reviewed and classified on the basis of technology used for the thermal management of PV modules. The paper also investigates one of the passive evaporative cooling technique to control the temperature rise of the PV module and enhancement in efficiency. Around 12oC reduction in PV panel temperature under maximum insolation and 7.7 % increase in average electric power generation efficiency was observed under this technique.Fri, 13 Dec 2019 20:30:00 +0100Design and fabrication of an effective micromixer through passive method
http://jcarme.sru.ac.ir/article_1100_208.html
Micromixer is a significant component of microfluidics particularly in lab-on-chip applications so that there has been a growing need for design and fabrication of micromixers with a shorter length and higher efficiency. Despite most of the passive micromixers that suffer from long mixing path and complicated geometry to increase the efficiency, our novel design suggests a highly efficient micromixer while taking advantage of having a short length. The novelty of our work stems from utilizing all three mixing techniques of injection, recombination, and zigzag mixing resulting in benefits such as multi-flow lamination and flow resistance reduction in microscale. Moreover, the contraction and expansion of the microchannel width improve mixing. The present work deals with the parametric study, numerical simulation, as well as experimental tests and characterization of small planar passive micromixer. The high mixing efficiency yield of 98.02 was obtained with the length of only 1857.8 microns which shows good agreement in comparison with numerical simulation.Fri, 31 Jan 2020 20:30:00 +0100An Experimental and Analytical Investigation of Flange Forming by Spinning Process
http://jcarme.sru.ac.ir/article_1166_0.html
The Tube flange is typically performed using welding, forging method, both of which cost time and effort. In this work, a metal spinning process to form tube flange was proposed. A flange-forming tool was developed based on the outer tube diameter to form the flange. It consists of three components namely collet, mandrill and roller. An experimental study was carried out to form the flange of lead tubes. Several flanged specimens were conducted at different working conditions. These working conditions are rotating speed (rpm), feed rate (mm/rev), and wall tube thickness (mm). The effects of working conditions on the flanging loads were investigated. An experimental analysis was carried out to illustrate the effect of the working conditions on the characteristics of the tube flange. The analysis showed that these working conditions have a clear influence on wall thickness, surface hardness, and flanging loads. A theoretical analysis to model the flange forming loads (axial, radial and tangential) was present. A comparison between analytical calculated and experimental measured loads was discussed. This comparison indicates a good agreement between the deducted forces analytically, and that measured experimentally.Fri, 22 Nov 2019 20:30:00 +0100Investigation of injection timing and different fuels on the diesel engine performance and emissions
http://jcarme.sru.ac.ir/article_999_208.html
Start of fuel injection and fuel type are two important factors affecting engine performance and exhaust emissions in internal combustion engines. In the present study, a one-dimensional computational fluid dynamics solution with GT-Power software is used to simulate a six-cylinder diesel engine to study the performance and exhaust emissions with different injection timing and alternative fuels. Starting the fuel injection was from 10 °CA BTDC to the TDC with an interval between two units and from alternative fuel bases (diesel), including methanol, ethanol, diesel, and ethanol compounds, biodiesel and decane was used. To validate the model, a comparison is made between simulation data and experimental data (including torque and power) showing the validation error is less than 6.12% and indicating the software model validation. Also, the modeling results show that decane fuel has higher brake power and brake torque of more than 6.10 % while fuel is injected at 10 °CA BTDC compared to the base fuel, and illustrates a reduction of 5.75 % in specific fuel consumption due to producing higher power. In addition, with the advance of injection timing compared to baseline, the amount of CO and HC in biodiesel fuel reduces to 83.88% and 64.87%, respectively, and the lowest NOX emission with the retardation of starting injection, to decane fuel is awarded. In general, the results show that decane fuel could be a good alternative to diesel fuel in diesel engines when it starts fuel injection at 10 °CA BTDC.Fri, 31 Jan 2020 20:30:00 +0100Finite Element Simulation of Crack Growth Path and Stress Intensity Factors Evaluation in ...
http://jcarme.sru.ac.ir/article_1161_0.html
This paper proposes a combination of FRANC2D/L (2D crack growth simulation program) and ANSYS mechanical program (3D structural analysis for fracture mechanic analysis. The comparisons between the two software were performed for different case studies for stress intensity factors (SIFs) as well as crack growth trajectory. Crack growth was numerically simulated by a step-by-step 3D and 2D finite element method. The SIFs were calculated by using the displacement correlation technique. The procedure consists of computing SIFs, the crack growth path, stresses, and strain distributions via an incremental analysis of the crack extension, considering two and three-dimensional analysis. The finite element analysis for fatigue crack growth was performed for both software based on Paris's law as well as the crack orientation was determined using maximum circumferential stress theory. The simulation results obtained in this study using finite element method provide a good agreement with experimental results for all the case studies reviewed.Fri, 25 Oct 2019 20:30:00 +0100Development length of laminar magnetohydrodynamics pipe flows
http://jcarme.sru.ac.ir/article_1020_208.html
In this article, a laminar magnetohydrodynamics (MHD) developing flow of an incompressible electrically conducting fluid subjected to an external magnetic field is considered. The aim of the study is to propose a correlation for computing the development length of the laminar MHD developing flow in a pipe. A numerical approach is considered to solve the problem. In the first step, the numerical Finite Volume Method (FVM) is conducted to analyze the problem. Hereafter, the artificial neural network (ANN) is used to develop the datasets and in the last step, the curve fitting is applied to find a correlation for prediction of the development length as a function of the Reynolds and Hartmann numbers. In addition, the effect of the problem parameters on the development length are studied. It is found that the development length declines with the increase of the Hartmann number and grows with the rising of the Reynolds number.Fri, 31 Jan 2020 20:30:00 +0100Thermo-mechanical characterization of post-consumer recycled high impact polystyrene from ...
http://jcarme.sru.ac.ir/article_1160_0.html
In this study, the effect of six successive recycling cycles of the recycled material from high impact polystyrene disposable cups on tensile properties, glass transition temperature, flexural, impact strength tests and fluidity were studied. It has been found that after increasing recycling, the molar mass and the viscosity decrease (a slight increase of melt flow index) until the fifth cycle, the maximum yielding stress decreased due to material brittleness .The impact strength has only been relatively influenced by a 17% increase, whereas the elongation at break and the young''s modulus dropped with reprocessing cycles. Glass transition temperature have undergone a remarkable decrease: It dropped in a consistent way, by the sixth cycle we measured a drop of almost 11°C compared to the virgin material, with a notable increase in flexural modulus and hardness. The resulted curves show the reliability of this material to be used after a specific number of processing in several industrial applications.Fri, 25 Oct 2019 20:30:00 +0100FEM investigation of drilling conditions on heat generation during teeth implantation
http://jcarme.sru.ac.ir/article_1156_0.html
Abstract The first step of implanting teeth is to drill a hole in the jaw bone. Excessive temperature produced during drilling is one of the destructive factors for bony tissue. If the temperature generation during surgical drilling exceeds the critical temperature, it could lead to osteonecrosis. This research intends to study drilling parameters such as drilling speed, feed rate, cooling condition and tool geometry by FEM method in order to achieve the most appropriate drilling conditions. Three dimensional modeling of lower jaw bone from the CT scan images was made by Mimics 10.01 software. In order to place the drill bit on the mandibular model, two teeth were removed from the final part of model by CATIA V5R20 software. DEFORM-3D (Version 10.2) was used for mandibular cortical bone drilling simulation. For this purpose, drill bits with different geometrical parameter including point angles of 90, 70, and 118 degrees and helix angles of 20, 23, and 30 degrees were designed in the software. The simulations were carried out using different feed rates (60, 90, 120 and 200 mm/min) and rotational speeds (200, 400, 800, and 1200 rev/min). The simulation results showed that the most appropriate conditions for the lowest temperature was as follows: 70 degrees for drill bit point angle, 23 degrees for helix angle, 200 mm/min for feed rate, and 200 rev/min for rotational speed. Also, by using coolant the maximum temperature reduced by approximately 12 degrees. The results also suggest that the rotational speed of 200 rev/min and feed rate of 200 mm/min have the largest thrust force in drilling area. The finite element results were validated by available experimental data.Fri, 11 Oct 2019 20:30:00 +0100Impact of thermal radiation and viscous dissipation on hydromagnetic unsteady flow over an ...
http://jcarme.sru.ac.ir/article_1144_0.html
The present numerical attempt deals the sway to transfer of heat and mass characteristics on the time-dependent hydromagnetic boundary layer flow of a viscous fluid over an exponentially inclined preamble stretching. Furthermore, the role of viscous heating, thermal radiation, uneven energy gain or loss, velocity slip, thermal slip and solutal slips are depicted. The prevailing time-dependent PDE’s are rehabilitated into coupled non-linear ODE’s with the aid of apposite similarity transformations and then revealed numerically by using the 4th order R-K method incorporate with shooting scheme. Influence of various notable parameters like porosity, inertia coefficient, radiation, Eckert number, velocity, thermal and solutal slip are explored via graphs and tables for the cases of assisting and opposing flows. Comparison amid the previously published work and the present numerical outcomes for the limiting cases which are received to be in a righteous agreement. Temperature increments with large values of the non-uniform heat source.Fri, 04 Oct 2019 20:30:00 +0100Investigating the Effects of Fuel Injection Strategies in a Dual-Fuel Diesel-H2 Compression ...
http://jcarme.sru.ac.ir/article_1143_0.html
In this computational research, the separate and simultaneous impacts of diesel direct injection timing, fuel spraying cone angle, and hydrogen gas addition on combustion characteristics, output emissions, and performance in a single-cylinder direct injection diesel engine was studied. In order to conduct the simulations, valid and reliable models for combustion, break-up, and for turbulence was used. The effects of fifteen fuel injection strategies based on characteristics such as time of fuel spraying (-15, -10 CA BTDC, and TDC) and nozzle cone angle (105, 115, 125, 145, and 160 degrees) under neat diesel combustion and diesel-hydrogen combustion engine operations conditions were explored. The obtained results indicated that the addition of H2 due to significant heating value has increased indicated power and improved indicated specific energy consumption at the expense of NOx emissions but considerably decreased CO and soot emissions simultaneously. By advancing injection timing, maximum pressure peak point, maximum temperature peak point, and maximum heat release rate peak point have increased and caused lower indicated specific energy consumption. However, using a wide spray angle (e.g., 160 cone degrees), resulted in lower indicated power and higher indicated specific energy consumption due to more fuel could spray in regions with lower oxygen concentrations compared to baseline operation case.Fri, 04 Oct 2019 20:30:00 +0100Effect of Shear State on Fracture of Refined Grain Pure Copper
http://jcarme.sru.ac.ir/article_1140_0.html
In recent decades, the industrial applications of refined grained pure copper and its alloys have been expanded. The properties such as high strength, high density and low deformability make these alloy more attractive. Hence, investigating the fracture mechanism of refined grained copper is of great significance. In this study, the fracture analysis of copper was investigated using the equal channel angular pressing process. Experimental results on metal alloys have demonstrated that stress state should be incorporated in the constitutive equations. Therefore, the fracture process was analyzed here by focusing on its relationship with the Lode angel variable. To prepare the ECAPed specimens, a die set was manufactured and tensile strength tests were carried out on dog-bone and notched flat plate specimens up to fracture. In addition, the mean value of grain sizes of the copper specimens were evaluated. The results demonstrate that the grain refining process profoundly enhances the load carrying capacity of copper specimens. Moreover, the dog-bone tensile tests clearly show that the peak value of the strain hardening in refined grained copper occurs up to two passes and after two passes the strain hardening drops. Furthermore, the results reveal that the Lode angel variable have a significant influence on the failure of the refined grained copper specimens.Fri, 20 Sep 2019 19:30:00 +0100Experimental Investigation of EDM Process Parameters by Using Pongamia Pinnata Oil blends as ...
http://jcarme.sru.ac.ir/article_1136_0.html
Electro Discharge Machining (EDM) is incredibly recognizable machining for ticklishness profiles in "difficult to machine" materials. In EDM, the material ejection of the cathode is cultivated through exact controlled electric pulse (the flash), which changes the metals of two terminals into dissolve and vaporize, and because of the breakdown of the dielectric medium. The most commonly used dielectric media are kerosene, paraffin, glycerin, transformer oil, EDM oil .all these are derived from petroleum. these dielectric media undergo pyrolysis and carbon soot formation is deposited on work electrode, and sometimes carbon precipitates into work. To overcome these effects vegetable oils are tried as alternate dielectric media. Pongamia Pinnetta is abundantly available in most of the countries, it's cheaper and non-edible. Pongamia Pinnata (PP) oil is extracting from plant seeds, and that is blended with EDM oil and several experimentations are done to find the suitability. Operational variables with respect to input and output parameters are identified. some of these are best EWR, MRR, TWR, and SR with applied current (I), pulse on time (Ton), and pulse off time (Toff) are which are picked as the input process factors, because for industrial application many machinists are choosing these three are the input parameters and other is constant and pick under specific requirements only. After successful completion of this experimentations, Pongamia Pinnata oil blends are fit for the industrial application using TECHNIQUE OF ORDER PREFERANCING WITH SIMILAR TO IDEAL SOLUTION [TOPSIS], It is observed that no carbon soot formation in the work component with PP oil as the dielectric.Tue, 27 Aug 2019 19:30:00 +0100Fracture analysis of pre-cracked and notched thin plates using peridynamic theory
http://jcarme.sru.ac.ir/article_1135_0.html
In this paper, the crack propagation and branching in the pre-cracked and notched samples have been modeled using nonlocal peridynamic theory. The bond-based peridynamic model has been numerically implemented which make it possible to simulate the various features of dynamic brittle fracture such as crack propagation, asymmetries of crack paths and successive branching. The fracture simulation of thin plates made of a brittle material with different crack and notch patterns has been considered. The molecular dynamics open-source free LAMMPS code has been updated to implement the peridynamic theory based modeling tool for two-dimensional numerical analysis. The simulations show that, the simulations time significantly decreases which is the core and distracting deficiency of the peridynamic method. Moreover, the simulated results demonstrate the capability of peridynamic theory to precisely predict the crack propagation paths as well as crack branching during dynamic fracture process. The good agreement between simulation and experiments is achieved.Tue, 27 Aug 2019 19:30:00 +0100Thermomechanical behaviour of Functionally Graded Plates with HSDT
http://jcarme.sru.ac.ir/article_1121_0.html
This paper presents closed-form formulations of higher order shear deformation theory (HSDT) to analyse the functionally graded plates (FGPs) acted upon a thermo-mechanical load for simply supported (SS) conditions. This theory assumes nullity conditions for transverse stress on bottom and top face of the FGPs. Moreover, considers the influence of both stresses and strains in the axial and transversal direction. In these improvements an accurate parabolic variation is assumed in the thickness direction for transverse shear strains. Therefore, this theory omits the use of correction factor for accurately estimating the shear stress. The physical properties of the FGPs are considered to change along the thickness using a power law. The equilibrium relations and constriants on all edges are attained by considering the virtual work. Numerical evaluations are attained based on Navier’s approach. The exactness and consistency of the developed theory are ascertained with numerical results for deflections and stresses of SS FGPs and it is deemed that numerical solutions for thermo-mechanical load will utilize as a reference in the future.Sat, 24 Aug 2019 19:30:00 +0100ANALYTICAL AND COMPARATIVE INVESTIGATIONS ON COUNTER FLOW HEAT EXCHANGER USING COMPUTATIONAL ...
http://jcarme.sru.ac.ir/article_1120_0.html
This paper presents a comprehensive and exclusive thermodynamic analysis of counter flow heat exchanger under various operating and geometrical conditions. Analysis system (ANSYS) workbench 14.0 has been used for computational analysis and comparison with previous literature has been carried out in view of variable temperature and mass flow rate of hot and cold fluids. An analytical and statistical method of computational fluid dynamics (CFD) analysis is used for simulation and validation of the heat exchanger under steady and dynamic operating conditions. A 3-D model of a heat exchanger having 1000 mm and 1200 mm outside and inside tube lengths with diameter 12.7 mm is designed in ANSYS environment using Renormalization Group (RNG) k-ε approach in order to get the better effectiveness of the system. The variable effects of the steady-state temperature and mass flow rate are investigated. The influence of turbulence over the temperature and pressure profiles is also studied. Moreover, the analytical outcome of the present investigations is compared with that of previous existing literature and found to be in agreement with the previous studies. The proposed analysis presents an in-depth perspective and simulation of temperature gradient profile through the length of heat exchanger. The proposed modified design of heat exchanger along with changing flow direction yields much better results with small computational error 0.66% to 1.004% and 0.83% to 1.05% with respect to change in temperature and mass flow rate respectively.Sat, 24 Aug 2019 19:30:00 +0100Entropy generation analysis of MHD forced convective flow through a horizontal porous channel
http://jcarme.sru.ac.ir/article_1118_0.html
Entropy generation due to viscous incompressible MHD forced convective dissipative fluid flow through a horizontal channel of finite depth in the existence of an inclined magnetic field and heat source effect has been examined. The governing non-linear partial differential equations for momentum, energy and entropy generation are derived and solved by using the analytical method. In addition; the skin friction coefficient and Nusselt number are calculated numerically and their values are presented through the tables for the upper and the bottom wall of the channel. It was concluded that; total entropy generation rate and Bejan number are reduced due to rise in the inclination angle of the magnetic field. Also, an increment in the heat source prop ups the fluid temperature and total entropy generation rate. This study will help to reduce the energy loss due to reversible process and heat dissipation. The results are very useful for chemical and metallurgy industries.Sat, 24 Aug 2019 19:30:00 +0100Effect of fuel injection pressure of microalgae spirulina biodiesel blends on engine characteristics
http://jcarme.sru.ac.ir/article_1082_0.html
The unvarying condition diesel engines used for commercial applications, transportation and industries also lead to the crisis of petroleum fuel diminution and ecological squalor caused by due to exhaust gases. Therefore, in this paper optimize the use of MSB in naturally aspirated, direct injection diesel engines, parameters of pure diesel (D100), 80% diesel + 20% microalgae spirulina (B20), 60% diesel + 40% microalgae spirulina (B40) and pure microalgae spirulina biodiesel (B100) were investigated at various fuel injection pressures (FIP) of 18 to 26 MPa and stationary injection timings (23.5° b TDC). The result shows that optimum effect can be obtained in 22 MPa FIP, with B20 bio-diesel without compromising the performance against diesel. B20 blend presented lesser NOX and smoke emissions by 13.7% and 22.2% respectively with no significant change in engine performance when compared to diesel at full load operating condition. The simulation and experiment results are verified at the same operating conditions.Tue, 18 Jun 2019 19:30:00 +0100Characteristics of fish oil biodiesel with the impact of diesel fuel addition on a CI engine
http://jcarme.sru.ac.ir/article_1072_0.html
The present study focuses on the optimization in the use of non-petroleum fuel derived from waste fish oil fuels, as a replacement for petroleum diesel fuel for compression ignition engine. The study comprises of comparison between results of fish oil biodiesel-diesel blends on a compression ignition engine. Fuel properties such as viscosity, density, heat value of fuel, cetane number and a flash point of fish oil biodiesel and its blends with diesel were studied. The fish oil biodiesel (60, 40, 20, and 0%) – diesel (40, 60, 80 and 100%) are blended at volume basis. The results shows reduction in thermal efficiency, temperature, particulate matter and nitrogen oxides emission; while showing an increase in higher specific fuel consumption, ignition delay, carbon dioxide and smoke emissions. The B20 fuel blend improves BTE by 4.7%, CO2 emissions has been increased by 2.56%, while SFC is lowered by 7.92% as compared to diesel fuel. In biodiesel blend (B20) the highest reduction in NOx by 14.9%, particulate by 4.22% is observed although smoke emission slightly rises with increase in fish oil in the blends, as compared to diesel fuel.Fri, 14 Jun 2019 19:30:00 +0100Effect of axial groove location, length & width ratio on the bearing properties and stability
http://jcarme.sru.ac.ir/article_1071_0.html
There are many industrial application of axial grooved journal bearing especially in turbo machinery. The stability is a very big issue for researcher, in high speed rotating machines. The axial groove journal bearing have a capacity to reduce the vibration and ability to resolve the heating problems as well as stability at higher speed. Dynamic performance parameters and stability of axial grooved hybrid journal bearings depend on the dimensions and orientations of groove in a great extent at higher speeds. In this work, a FORTRAN program has been used to solve Reynolds governing equation. The bearing performance characteristics have been simulated for the various dimensions and orientation of groove. Non linear journal centre trajectories are drawn for different Reynolds number for stability analysis. It has been found that the smaller groove length has resulted in lower bearing capacity whereas smaller groove width yielded higher bearing capacity and the turbulence decreases the stability. The groove location also strongly affects most performance parameter. The optimum location of groove axis was obtained between 60 degree to 90 degree to the load line.Fri, 14 Jun 2019 19:30:00 +0100Mechanism of surface generation in grinding of AA6061-TiB2/ZrB2 in-situ composites
http://jcarme.sru.ac.ir/article_1070_0.html
In-situ composites are gained the attention of worldwide researchers in the interest of its greater mechanical properties at the lower reinforcement ratio. Controlling the surface quality of the component is a paramount task in grinding process in order to withstand the creep and fatigue load at service conditions. The current effort is intended to examine the mechanism of surface generation in grinding of AA6061-TiB2/ZrB2 in-situ composites under different reinforcement ratio, grinding parameters and wheel materials. The analysis of results indicates that the grinding of unreinforced alloy is complicated than the composites. Diamond wheel yields superior performance by generating lesser surface roughness and subsurface hardness at all grinding conditions. Among the various grinding parameters, grinding speed and grinding depth are more sensitive than other parameters. This experimental investigation helps to control the surface roughness and subsurface at various grinding conditions. Understanding of surface generation mechanism in grinding of in-situ composites helps to employ the grinding process for economic machining rate without negotiating the surface quality.Fri, 14 Jun 2019 19:30:00 +0100Heat transfer characteristics of methane-air diffusion flames impinging normally on plane surfaces
http://jcarme.sru.ac.ir/article_1067_0.html
Theoretical investigation of turbulent flame impinging normally on plane surfaces has been done to determine the average Nusselt number and the plate heat flux distribution as functions of jet Reynolds number, equivalence ratio (ER) and separation distance (H/d). The analysis is established on mathematical formulation of the governing equations for conservation of mass, momentum and energy. The turbulence phenomena is analyzed by the help of RNG k-ε turbulence model. The radiative heat transfer model has been designed by using Discrete Ordinates (DO) radiation model. It has been found that the heat flux gradually increases with the radial distance towards the plate centre and attains a maximum value at a location slightly away from stagnation point. The peak value in the local heat flux comes closer to the stagnation point when the height between the plates and the nozzle increases. Effects of variation of dimensionless separation distance on heat transfer characteristics have been investigated. It is observed that heat flux gradually improves when the value of H/d changes from 12 to 8 and decreases near the stagnation region with the further decrease in H/d from 8 to 4.Fri, 14 Jun 2019 19:30:00 +0100Analytical study of heat and mass transfer in axisymmetric unsteady flow by ADM method
http://jcarme.sru.ac.ir/article_1066_0.html
Findings the solutions for heat and mass transfer problems is significant due to their applications in the science and engineering. In this study, Adomian decomposition method (ADM) is chosen as a robust analytical method for investigation of heat and mass transfer characteristics in a viscous fluid which is squeezed between parallel plates. In order to ensure the validation of results, the obtained results of ADM method are compared with the numerical (Runge-Kutta method) results and reasonable agreement was observed. These comparisons confirm that Adomian decomposition method is a powerful and reliable approach for solving this problem. Then, diverse governing parameters namely; the squeeze number, Prandtl number, Eckert number, Schmidt number and the chemical reaction parameter are comprehensively studied. Our findings reveal that Sherwood number rises as Schmidt number and chemical reaction parameter increases while it declines with growths of the squeeze number. Likewise, it can be found that Nusselt number enhances with rise of Prandtl number and Eckert number and it decreases when the squeeze number increases.Fri, 14 Jun 2019 19:30:00 +0100Application of Image-based Acquisition Techniques for Additive Manufacturing using Canny Edge ...
http://jcarme.sru.ac.ir/article_1062_0.html
Edge is an indispensable characteristic of an image, defined as the contour between two regions with significant variance in terms of surface reflectance, illumination, intensity, color and texture. Detection of edges is a basic requirement for diverse contexts for design automation. This study presents a guideline to assign appropriate threshold and sigma values for Canny edge detector to increase the efficiency of additive manufacturing. The algorithm uses different combinations of threshold and sigma on a color palette and the results are statistically formulated using multiple regression analysis with an accuracy of 95.93%. An image-based acquisition technique system is designed and developed for test applications to create three-dimensional objects. In addition, graphical user interface is developed to convert a selected design of a complex image to a three-dimensional object with generation of Cartesian coordinates of the detected edges and extrusion. The developed system reduces the cost and time of developing an existing design of an object for additive manufacturing by 20% and 70% respectively.Sat, 08 Jun 2019 19:30:00 +0100Analysis of Factors Affecting Delamination in Drilling GFRP Composite
http://jcarme.sru.ac.ir/article_1061_0.html
Composite materials have proven their applicability for various structural components. Glass fiber reinforced plastic (GFRP) composite materials have potential applications in aerospace, automobile related industries due to their excellent properties. Drilling is important operation for composite structures during final assembly. This paper investigates the factors affecting delamination in glass fiber reinforced plastic (GFRP) composite during the drilling process. Drill speed and feed rate are selected two parameters affecting delamination during the drilling process. Response surface methodology (RSM) approach has been used for experimental design and analysis of variance (ANOVA). Delamination evaluated at entry, middle and exit position of the hole. An attempt has been made to optimize speed and feed for minimization of delamination at these three positions using grey relational analysis (GRA). The results of this work will help in selecting an optimum level of speed and feed to minimize delamination at entry, middle, and exit position of the hole improving quality of the drilled hole.Sat, 01 Jun 2019 19:30:00 +0100Experimental Evaluation and Estimation of Frictional Behavior of Polymer Matrix Composites
http://jcarme.sru.ac.ir/article_1060_0.html
As the fiber reinforced polymer matrix composites gives good strength and can work in rigorous environmental conditions, nowadays more focus is given to study the behavior of these materials under different operating conditions. Due to the environmental concern focus on the natural fiber reinforced polymer matrix composite (NFRPC) is enhancing both in research and industrial sectors. Currently focus has been given to unify solid fillers with the NFRPC to improve its mechanical and tribo properties. Aligned to this, the present work discusses the effect of various weight fraction of fillers (Flyash, SiC and graphite) on the frictional behavior of natural fiber (cotton) polyester matrix composites. The specimen prepared with Hand lay-up process followed by compression molding. A plan of experiments, response surface technique, was used to obtain response in an organized way by varying load, speed and sliding distance. The test results reveal that different weight concentration of fillers has considerable result on the output. The frictional behavior of materials evaluated by general regression and artificial neural network (ANN). The validation experiment effects show the estimated friction by using ANN was more closer to experimental values compare to the regression models.Sat, 01 Jun 2019 19:30:00 +0100Novel Numerical Solution of Non-linear Heat Transfer of Nanofluid over a Porous Cylinder: ...
http://jcarme.sru.ac.ir/article_1059_0.html
The study aims to investigate numerically a two dimensional, steady, heat transfer over a cylinder in porous medium with suspending nanoparticles. Buongiorno model is adopted for nanofluid transport on free convection flow taking the slip mechanism of Brownian motion and thermophoresis into account. Boussinesq approximation is considered to account for buoyancy. The boundary layer conservation equations are transformed into dimensionless, and then elucidated using robust Keller-box implicit code numerically. The numerical results are displayed graphically and deliberated quantitatively for various values of thermo-physical parameters. Our results shows that, increasing Forchheimer parameter, Λ, clearly swamps the nanofluid momentum development, decreasing the flow for some distance near the cylinder viscous region, later its reverse the trend and asymptotically reaches the far field flow velocity. Furthermore, as increases thermophoresis, heat transfer and nanoparticle volume concentration increased in the boundary layer. The present results are validated with the available results of similar study and is found to be in good coincident. The study finds applications in heat exchangers technology, materials processing and geothermal energy storage etc.Sat, 01 Jun 2019 19:30:00 +0100Multi-Objective Particle Swarm Optimization of WEDM Process Parameters for Inconel 825
http://jcarme.sru.ac.ir/article_1058_0.html
With the increased diversity of the customer demand and complexity of the product Inconel 825 is widely used to meet the actual needs especially in aerospace industry. It is difficult-to-cut material because of its high toughness and hardness. The present research attempts to optimize the process parameters of wire electric discharge machining (WEDM) during cutting operation of Inconel 825. WEDM characteristics such as pulse-on time (Ton), pulse-off time (Toff), spark gap voltage (SV), peak current (IP),wire tension (WT), wire feed (WF) are taken into consideration. Performance was measured in terms of material removal rate (MRR), surface roughness (SR) and wire wear ratio (WWR). Central composite design (CCD) of response surface methodology (RSM) at α value of ± 2 was employed to establish the mathematical model between process parameters and performance measures. Multi-objective particle swarm optimization (MOPSO) algorithm has been used to find the Pareto optimal solutions. It uses the concept of dominance to find the non dominated set in the entire population and crowding distance approach to find best Pareto optimal solutions with a good diversity of objectives. The confirmation experiments of MOPSO algorithm shows the significant improvement in MRR (27.934 to 31.687 mm2/min), SR (2.689 to 2.448μm) and WWR (0.027 to 0.030). SEM micrograph studies showed the number of cracks, pockmarks, craters, and pulled out material on the workpiece and wire electrode surface. Energy Dispersive X-ray analysis is performed to investigate the presence of elements on the work surface other than base material.Sat, 01 Jun 2019 19:30:00 +0100Transient Analysis of Radiative Hydromagnetic Poiseuille fluid flow of Two-step Exothermic ...
http://jcarme.sru.ac.ir/article_1056_0.html
In this research, the transient analysis of radiative combustible viscous chemical reactive two-step exothermic fluid flow past a permeable medium with various kinetics i.e Bimolecular, Arrhenius and Sensitized are investigated. The hydromagnetic liquid is influenced by a periodic vicissitudes in the axial pressure gradient and time along the channel axis in the occurrence of walls asymmetric convective cooling. The convectional heat transport at the wall surfaces with the neighboring space takes after the cooling law. The non-dimensional principal flow equations are computationally solved by applying convergent and absolutely stable semi-implicit finite difference techniques. The influences of the fluid terms associated with the momentum and energy equations are graphically presented and discussed quantitatively. The results show that the reaction parameter (𝜆) is very sensitive and it is therefore needs to be carefully monitor to avoid systems blow up. Also, a rise in the values of the second step term enhances the combustion rate and thereby reduces the release of unburned hydrocarbon that polluted the environment.Sat, 25 May 2019 19:30:00 +0100Numerical analysis of heat transfer in helical tube with the aluminum oxide (Al2O3) nano fluid ...
http://jcarme.sru.ac.ir/article_1055_0.html
The most important reason for the design of curved tubes is increasing the heat transfer between the fluid and the wall which has provided many applications in various industries such as air conditioning, micro-electric, heat exchangers and etc. The aim of this study is numerical investigation of nano fluids flow in spiral tubes with injection of base fluid in different Reynolds numbers. According to, the effects of volume fraction, nanoparticle diameter, fluid injection, Reynolds number and spin effects on heat transfer and flow in the spiral tube are discussed. In this study, a mixture of water-Al2O3 is selected to model nano fluid flow in order to investigate the changes of the heat transfer rate by the injection of nanofluid to the base fluid in the spiral tube at different angles. The results show that by use of nanoparticles, the rotational effects of tube and the injection process increase the heat transfer performance. It was found that increasing the volume fraction has a direct effect on increasing the heat transfer coefficient. As the volume fraction increases from 2% to 8%, the heat transfer coefficient increases by 2%. In fact, the effect of nanoparticles on the thermal conductivity of the fluid causes this increase. Also, injection of fluid into the stream due to disturbance in the thickness of the boundary layer and the further mixing of the fluid layers which increases the heat transfer. 90-degree injection has the best effect. Cu2O3 –water nano fluid mixture has also been used. The results are presented in this paper and compared with the Al2O3 nano fluid model which indicates that the increase of heat transfer rate in Cu nano fluid was higher than aluminum nano fluid due to higher heat transfer capacity of Copper.Sat, 25 May 2019 19:30:00 +0100OPERATIONAL TRENDS OF A MINI PARABOLIC SOLAR COLLECTOR FOR AGRICULTURAL PURPOSES IN A ...
http://jcarme.sru.ac.ir/article_1047_0.html
The mode of operation of mini parabolic solar panels made of germanium, mild steel and aluminium were investigated experimentally, as means of providing heated water on a farmland; the process was also modelled. Angular adjustments of the solar collectors from 70-90o were adopted in order to determine, the best material of construction for the parabolic solar collector and the angular orientation with the highest heat collection tendency and absorption rate. The highest quantity of adsorbed heat/best heating effect of the solar collector was obtained at an angular orientation of 80o for mild steel and aluminium. It was also observed that, the parabolic solar collectors have their optimum exposure times, after which, the heating rate drops or there is loss of heat from its surface. The experimental and model estimates, in terms of heat absorption for the mild steel solar collector at 70 and 90o angular tilts, shows that, the optimum heating time was 40 minutes while at 80o, the optimum heating time was found to be 50 minutes.Sun, 14 Apr 2019 19:30:00 +0100Numerical modeling of three-phase flow through a Venturi meter using the LSSVM algorithm
http://jcarme.sru.ac.ir/article_1046_0.html
One of the challenging problems in the Oil & Gas industry is accurate and reliable multiphase flow rate measurement in a three-phase flow. Application of methods with minimized uncertainty is required in the industry. Previous developed correlations for two-phase flow are complex and not capable of three-phase flow. Hence phase behavior identification in different conditions to designing and modeling of three-phase flow is important. Numerous laboratory and theoretical studies have been done to describe the Venturi multiphase flow meter in both horizontal and vertical flow. However, it is not possible to select the measurement devices for all similar conditions. In this study a new venturi model was developed that implemented in Simulink/Matlab for predicting mass flow rate of gas, water and oil. This models is simple and semilinear. Several classified configurations of three phase flow were simulated using Computational Fluid Dynamics (CFD) analysis to get hydrodynamics parameters of the flows to use as inputs of the model. The obtained data, used as test and train data in Least squares support vector machine (LSSVM) algorithm. The pressure drop, mass flow rate of gas, oil and water have been calculated with LSSVM method. Two tuning parameters of LSSVM, namely γ and σ^2, obtained as 1150954 and 0.4384, 53.9199 and 0.18163, 8.8714 and 0.14424, and 10039130.2214 and 0.74742 for pressure drop, mass flow rate of oil, gas mass flow rate, water mass flow rate, respectively. Developed models was found to have an average relative error of 5.81%, 6.31% and 2.58% for gas, oil and water respectively.Sun, 14 Apr 2019 19:30:00 +0100LabVIEW Implementation of an Enhanced Nonlinear PID Controller Based on Harmony Search for ...
http://jcarme.sru.ac.ir/article_1045_0.html
This paper presents a practical implementation for a new formula of nonlinear PID (NPID) control. The purpose of the controller is to accurately trace a preselected position reference of one stage servomechanism system. The possibility of developing a transfer function model for experimental setup is elusive because of the lack of system data. So, the identified model has been developed via gathering experimental input/output data. The performance of the enhanced nonlinear PID (NPID) controller had been investigated by comparing it with linear PID controller. The harmony search (HS) tuning system had built to determine the optimum parameters for each control technique based on an effective objective function. The experimental outcomes and the simulation results show that the proposed NPID controller has minimum rise time and settling time through constant position reference test. Also, the NPID control is faster than the linear PID control by 40% in case of variable position reference test.Sat, 13 Apr 2019 19:30:00 +0100Investigation of hot metal gas forming process of square parts
http://jcarme.sru.ac.ir/article_1044_0.html
Aluminum alloys are considered a lot in the automotive and aerospace industry because of their high strength to weight ratio. In this manuscript, the gas forming process of aluminum AA6063 tubes at high temperatures up to 500°C is investigated, through experimental and numerical tests. Therefore, an experimental setup is prepared and so, tube specimens are formed in a die with square cross section. Finite element simulation of the hot gas forming process is carried out to investigate the effects of process parameters including time period of forming process, temperature, and loading path. Uniaxial tensile tests under various temperatures and strain rates is performed, in order to obtain flow stress curves of the material. Corner radius and thickness distribution of tubular formed parts is investigated. The results show smaller corner radii could be formed at higher temperatures, whereas lower forming pressure is necessary. Increasing the time period of the process enhances the corners of the specimens to be formed. In addition, the maximum of formability is obtained when the gas pressure increases rapidly at the beginning of the process. However, the increasing rate of gas pressure must be reduced to form a smaller corner radius.Sat, 13 Apr 2019 19:30:00 +0100Application of Combined Mathematical modeling/Optimization Methods Coupled Pitch Controller in ...
http://jcarme.sru.ac.ir/article_832_0.html
A common method utilized in wind turbines is pitch angle control whereby via varying the angle of wind turbine blades around their own axis, power generated at high speeds of wind is held around maximum amount and is kept away from the severe mechanical stress on wind turbine. In current study, in order to control pitch angle, a control method based on using PI controller is suggested. Therefore, gains of the PI controller are regulated through combining the Firefly evolutionary algorithm and MLP neural network in such a way that the controller at its output sends a suitable controlling signal to the pitch actuator to set the pitch angle and so by varying the blades pitch angle suitably at high speeds of wind, the produced generator power remains around its nominal value. A wind turbine 5MW made by NREL (National Renewable Energy Laboratory) has been utilized based on FAST software code to simulate and analyze the results. The simulation results show that proposed method has a good performance.Tue, 11 Sep 2018 19:30:00 +0100Dynamic response of a shaft of a Pelton turbine due to impact of water jet
http://jcarme.sru.ac.ir/article_1043_0.html
Performance and reliability of any rotating machine can be studied by proper dynamic analysis of the machine. In this regard, this paper presents the method to study the dynamic response of the shaft of a Pelton turbine due to the impact of water jet. Equations of motion for the bending vibration of Pelton turbine assembly, in two transverse directions, is developed by using Lagrange equation of motion with the help of assumed modes method. The Pelton wheel is assumed as a rigid disk attached on Euler-Bernoulli shaft. The impact provided by the water jet is represented in the form of Fourier series. Critical speeds of the system are determined by performing free vibration analysis and presented in the form of Campbell diagram. The response plots due to impact of water are generated by performing forced response analysis. Both free and forced analyses are carried out by considering first three modes of vibration.Sat, 13 Apr 2019 19:30:00 +0100Numerical modeling and comparison study of elliptical cracks effect on the pipes straight and ...
http://jcarme.sru.ac.ir/article_1025_0.html
The present work deals with the effect of an external circumferential elliptical crack located at thickness transition on a varied stepped diameter pipe . The purpose is the application of the extended finite element method (XFEM) for the calculation of SIF at the thickness transition region of pipe considering internal pressure and compare the effect of the crack between pipes straight and with thickness transition. To model a crack with precision , enrichment functions are used to enrich the displacement approximation, the level set functions are calculated from the crack mesh and definition of the strategy of integration has been performed. A comparative study is made on SIF of crack defect in straight pipe compared to one with thickness transition using XFEM for the crack and pipe geometrical parameters variations. The result shows that the XFEM is an effective and practical tool for elliptic crack modeling in a pipe with thickness transition because a crack is easily modeled through enrichment functions.The comparison of the SIF of a similar defect between pipes shows that a pressurized pipe with thickness transition is more sensitive to the used cracks.Tue, 19 Feb 2019 20:30:00 +0100Parametric study on axial compressor performance in design condition
http://jcarme.sru.ac.ir/article_1024_0.html
In This paper, a parametric study of compressor performances was performed by streamline curvature method (SLC). Effects of three input parameters in design process, e.g., number of blades, distribution of blade thickness, and blade sweep angels, on the main objective parameters in aerodynamic design, e.g., velocity distribution, efficiency and pressure ratio, has been investigated in the parametric study. Initially, a certain two stage axial compressor has been designed by SLC. Validation of the results is confirmed by comparing the obtained results with the experimental ones. Regarding various values for aforementioned input parameters, the first stage of the axial compressor is redesigned and the output parameter is established. Therefore, the sensitivity of the design results to each of the aforementioned parameters is recognized. Results show that increasing the blades sweep angle causes to improve the flow behavior such as efficiency and pressure ratio in axial fan and reducing it have a completely contrary result. Also, reducing the rotors blades number leads to an increase in the pressure ratio and efficiency while its increase cause to a contrary result. , it is concluded that reduction in the blades number has the stronger effect on the performance parameters than its increment. The results also show that effect of the thickness in the hub is greater than the thickness of the tip and its increase leads to reduce both efficiency and pressure ratio.Tue, 19 Feb 2019 20:30:00 +0100Cooling a hot obstacle in a rectangular enclosure by using a MHD nanofluid with variable properties
http://jcarme.sru.ac.ir/article_991_0.html
In this study, cooling of a hot obstacle in a rectangular cavity filled with water-CuO nanolfuid has been examined numerically. This cavity has an inlet and outlet and the cold nanofuid comes from the left side of the cavity and after cooling the hot obstacle, it goes out from the opposite site. All of the walls are insulated, and the SIMPLER algorithm has been employed for solving the governing equations. The effects of fluid inertia, magnetic field strength, volume fraction of nanoparticles, and the place of outlet on heat transfer rate has been scrutinized. According to the results, the average Nusselt number builds up as the outlet place goes down. In other words, when the outlet is located at the bottom of the cavity, the rate of the heat transfer is maximum. Moreover, by increasing the Reynolds number and volume fraction of nanoparticles, the average Nusselt number builds up as well.Tue, 22 Jan 2019 20:30:00 +0100Investigation of natural convection heat transfer of MHD hybrid nanofluid in a triangular enclosure
http://jcarme.sru.ac.ir/article_976_0.html
Natural convection heat transfer is studied numerically in a triangular enclosure. The enclosure is isosceles right triangle and its bottom wall is hot, the hypotenuse is cold and the other wall is adiabatic. Also, a vertical magnetic field is applied in the enclosure, and there is hybrid nanofluid inside the enclosure. This study is conducted for Rayleigh numbers of 103-105, the Hartmann numbers between 0-80, and the volume fraction of nanofluid is between 0-2 percent. Based on the obtained results, as the Hartmann number augments, the temperature of the center of the enclosure decreases due to weakening of the heat transfer flow by increasing the magnetic field forces. In addition, as the Hartmann number augments, the streamlines approach to the walls because the horizontal momentum forces decrease when the Hartmann number increases. Furthermore, by increasing the density of nanoparticles, the heat transfer rate increase, and as a result, heat transfer builds up. Finally, heat transfer improve when the hybrid-nanofluid is employed rather than ordinary nanofluid.Mon, 07 Jan 2019 20:30:00 +0100INCLINED LORENTZIAN FORCE EFFECT ON TANGENT HYPERBOLIC RADIATIVE SLIP FLOW IMBEDDED CARBON ...
http://jcarme.sru.ac.ir/article_900_0.html
The present paper focuses on numerical study for an inclined magneto-hydrodynamic effect on free convection flow of a tangent hyperbolic nanofluid embedded with Carbon nanotubes (CNTs) over a stretching surface taking velocity and thermal slip into account. Two types of nanoparticles are considered for the study; they are single and multi-walled nanotubes. The presentation of single-parameter group (Lie group) transformations reduces the independent variable number by one, and hence the partial differential governing equations with the supplementary atmospheres into an ordinary differential equation with the appropriate suitable conditions. The obtained ordinary differential equations are then numerically solved by employing fourth order Runge-Kutta technique along with shooting method. The effects of the various parameters governing the flow field are presented with the help of graphs. The investigation reveals that the non-Newtonian MWWCNTs Tangent hyperbolic nano-liquid reduces the friction near the stretching sheet contrasting SWCNTs. This combination can be used as a friction lessening agent/factor. Usage of CNTs shows an excellent performance in enhancing the thermal conductivity of the nanoliquid and single wall carbon nanotubes (SWCNTs) has higher thermal conductivity than multi wall carbon nanotubes (MWCNTs) even in the presence of radiative heat transfer and heat source. Comparison with existing results available in literature is made and had an excellent coincidence with our numerical method.Fri, 26 Oct 2018 20:30:00 +0100Experimental study and numerical simulation of three dimensional two phase impinging jet flow ...
http://jcarme.sru.ac.ir/article_902_0.html
Hydrodynamic of a turbulent impinging jet on a flat plate has been studied experimentally and numerically. Experiments were conducted for the Reynolds number range of 72000 to 102000 and a fixed jet-to-plate dimensionless distance of H/d=3.5. Based on the experimental setup, a multi-phase numerical model was simulated to predict flow properties of impinging jets using two turbulent models. Mesh-independency of the numerical model was studied to ensure the preciseness of results. Numerical and experimental forces on the target plate were compared to examine performance of turbulent models and wall functions. As a result, the force obtained by the Reynolds stress turbulent model alongside with non-equilibrium wall function was in good agreement with the experiment. The correlation equations were obtained for predicting the water thickness over the target plate and impingement force versus Reynolds number. It was also indicated that the maximum shear stress on the target plate was located at radial dimensionless distance of r/d=0.75.Fri, 26 Oct 2018 20:30:00 +0100