Journal of Computational & Applied Research in Mechanical Engineering (JCARME)
https://jcarme.sru.ac.ir/
Journal of Computational & Applied Research in Mechanical Engineering (JCARME)endaily1Tue, 01 Sep 2020 00:00:00 +0430Tue, 01 Sep 2020 00:00:00 +0430A systematic approach for a better thermal management of photovoltaic systems- A review
https://jcarme.sru.ac.ir/article_1176.html
Solar energy is the highly recognized energy source, capable of fulfilling the world&rsquo;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.State of the art in friction stir welding and ultrasonic vibration-assisted friction stir welding of similar/dissimilar aluminum alloys
https://jcarme.sru.ac.ir/article_1533.html
Researchers worked on many facets of joining of similar/dissimilar aluminum alloys using different joining techniques and came up with their own recommendations. Friction Stir Welding (FSW) is widely preferred for joining aluminum alloys being an economical alternative to produce high-quality welds. However, obtaining high strength welded joints without the detrimental and visible effects still needs attention considering the effect of hybrid FSW techniques, tool material, and geometry, process parameters (tool rotation, welding speed, and plunge depth), and post welding treatments. This study presents state of the art with the authors' own inferences on the evaluation of FSW performances in terms of joint tensile strength, fatigue strength, corrosion resistance, residual stresses, microstructure, and microhardness. This study also presents attempts made by the researchers on modeling and parametric optimization of FSW to finding scope for application of advanced optimization techniques and development of predictive models for mechanical properties of welded joints. This study emphasizes more studies required on the comparative evaluation of FSW performance with the application of ultrasonic frequency combinedly or individually on advancing and retreating sides of plates.FEM investigation of drilling conditions on heat generation during teeth implantation
https://jcarme.sru.ac.ir/article_1156.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.Free vibration analysis of CFRP cylinders with torispherical heads: Experimental and numerical investigations
https://jcarme.sru.ac.ir/article_1515.html
Pressure vessels are used in a variety of applications in many engineering applications. The thin walled cylinders with torispherical heads have been widely used as pressure vessels in engineering applications. In this paper, the free vibration behavior of carbon fiber reinforced composite cylinders ended with torispherical heads with various boundary conditions is investigated. The shape of a torispherical head is consists of a sphere of large radius and a much smaller minor radius at the knuckle. The numerical calculation with finite element method is obtained and the results were compared with the experimental data to confirm the accuracy of the numerical solution. The acceptable accordance between experimental and numerical results leads to use of numerical model instead of expensive experimental tests. In addition, the effects of the thickness of torispherical head and cylindrical section and the lengths of cylinder and torispherical head on vibrational behavior of the structure are studied.Entropy generation analysis of MHD forced convective flow through a horizontal porous channel
https://jcarme.sru.ac.ir/article_1118.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.Numerical study of built-in cylinders’ effects on flow pattern and heat transfer characteristics in a laminar channel flow
https://jcarme.sru.ac.ir/article_1495.html
A numerical simulation of laminar fluid flow and heat transfer over built-in cylinders in a channel is presented. Effects of cylinders that located in a rectangular channel with constant wall temperature on flow and heat trans-fer have been investigated by the drag coefficient on cylinders wall, skin-friction factor on channel wall, Strouhal number, pumping factor, Nusselt number, and Performance Index (PI) factor, which denotes the heat trans-fer in terms of the pressure drop. Results are validated by the most reliable published works in literature. Effects of Reynolds number and blockage ratio (&beta;) for the equilateral triangular cylinder for 120&le;Re&le;180 and 0.15&le;&beta;&le;0.55 on flow and heat transfer is investigated with more details. Results indicated that by increasing Re for constant blockage ratio, the drag coefficient, Strouhal number, and Nusselt number increase, but the skin-friction coefficient, pumping factor, and PI factor decrease subse-quently. Additionally, with increase in blockage ratio at constant Re, the drag coefficient, skin-friction coefficient, pumping factor, and Strouhal number grow up, but Nusselt number diminishes and PI factor has an op-timum range. Furthermore, results reveal that variation in blockage ratio has more significant effects on the flow and heat transfer than variation in Reynolds number.Transient analysis of radiative hydromagnetic poiseuille fluid flow of two-step exothermic chemical reaction through a porous channel with convective cooling
https://jcarme.sru.ac.ir/article_1056.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.Non destructive damage severity estimation in beam using change in extended cross modal strain energy
https://jcarme.sru.ac.ir/article_1494.html
This paper presents an extended cross modal strain energy change method to estimate the severity of damage associated with limited modal data in beam-like structures. This method takes in account the correlation between the analytical modal data and the measured incomplete modal data. A procedure was proposed and the analytical elemental stiffness of the damaged element after it is localized is included in quantification of the measured single damage extent. A three-dimensional numerical beam model with different damage cases is used to simulate the CMSE method application and to getting the bending displacements of the damaged element. An experimental modal analysis on a cantilever beam subjected to a controlled crack levels was carried out to demonstrate the effectiveness of the extended CMSE method. The severity magnitude of the damage was predicted within an acceptable error range through the using validation process. Analysis results demonstrate that the presented damage method effectively quantifies single damage severity in beam like structure and can be applied in engineering practice.Investigating the effects of fuel injection strategies in a dual-fuel diesel-H2 compression ignition engine
https://jcarme.sru.ac.ir/article_1143.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.Investigation of process parameters for T-joint aluminum alloy 6061-T6 with nanocomposites material friction stir welding based on the Taguchi method
https://jcarme.sru.ac.ir/article_1484.html
Surface layer in many engineering applications is strengthened by ceramic grains where the main parts have higher structure toughness of than the original material. This paper presents the effect of four process parameters that have taken into consideration using Taguchi technique based on L9 orthogonal array. These parameters are;1) transverse speed, 2) type of nano-powders, 3) rotational speed, and 4) groove&rsquo;s depth friction stir welding T-joints aluminum alloy 6061-T6. This work combines between welding T-joint sections and creating MMNCs in welding region simultaneously.The predicted optimum parameters and their percentage of contribution were estimated, utilizing the analysis of variance and signal to noise ratio techniques, depending on tensile test in skin and stringers direction, and hardness test of the joint. Optical microscope and scanning electron microscope (SEM) analysis were used to verify the microstructure and dispersion of nano-powders in welding joint. The best ultimate tensile stress (UTSskin) was equal to (177MPa) for the skin welded part, were obtained at the optimal conditions of 1550rpm rotational speed, 15mm/min transverse speed, Al2O3 type of powder and 1mm groove&rsquo;s depth. SEM micrographic for metal matrix nanocomposite of all nine experiments revealed that the nano-particles are irregular dispersed in nugget zone due to one pass. The rotational speeds of 960rpm, the transverse speed of 15mm/min, type of powder TiO2, and groove&rsquo;s depth of 1.5mm, give the greatest hardness value of 80HV in nugget zone. Analysis of variance showed that the groove&rsquo;s depth is the most significant parameter in this investigation.Dynamic response of a shaft of a Pelton turbine due to impact of water jet
https://jcarme.sru.ac.ir/article_1043.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.A CFD analysis of the effects of injection and suction through a perforated square cylinder on some thermo-fluid parameters
https://jcarme.sru.ac.ir/article_1478.html
< p>The effects of uniform injection and suction through the surfaces of a perforated square cylinder on the vortex shedding, heat transfer and some aerodynamic parameters have been investigated numerically. The finite-volume method has been used for solving the Navier-Stokes equations for incompressible, turbulent near-wake flow (Re=21400) with the k-ɛ turbulence model equations. To find the optimum conditions, the effects of injection and suction through the front surface (case Ⅰ), the rear surface (case Ⅱ), top-bottom surfaces (case Ⅲ) and all surfaces (case Ⅳ) with various injection/suction coefficient Γ are studied. The results reveal that parameters such as pressure and drag coefficients and Nusselt number are influenced drastically in some cases as well as flow field parameters. For instance, the maximum reduction of the drag coefficient occurs at case Ⅳ while the maximum increase and reduction of Nu number occur at (|Γ|)=0.025 for all cases about 46% and 32%, 61% and 63%, 92% and 60% and 180% and 115% for cases Ⅰ, Ⅱ, Ⅲ and Ⅳ respectively.Inclined Lorentzian force effect on tangent hyperbolic radiative slip flow imbedded carbon nanotubes: lie group analysis
https://jcarme.sru.ac.ir/article_900.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.Bending of Exponentially Graded Plates using new HSDT
https://jcarme.sru.ac.ir/article_1474.html
The present paper considers the devise and development of a novel theory to examine the flexure analysis of exponentially graded plates exposed to thermal and mechanical loads. The properties such as Elastic moduli and thermal moduli are assumed to vary exponentially along the thickness by keeping the poisons ratio as constant. This theory fulfils the nullity conditions on the upper side and lower side of the exponentially graded plates for transverse shear stress. The Hamilton&rsquo;s principle has been used to derive the equation of motion. The present theory numerical results are assessed with three-dimensional elasticity solutions and the results of other authors available in the literature. The influence of thermo mechanical loads and thickness ratios and aspect ratios on the bending response of exponentially graded plates are studied in detail. The analytical formulations and solutions presented herein could provide engineers with the potential for the design and development of exponentially graded plates for advanced engineering applicationsCooling a hot obstacle in a rectangular enclosure by using a MHD nanofluid with variable properties
https://jcarme.sru.ac.ir/article_991.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.Numerical investigation and optimization the mechanical behavior of thin-walled tubes with combined geometric
https://jcarme.sru.ac.ir/article_1418.html
In this study, the crush behavior and energy absorption of various thin-walled structures under quasi-static loading are investigated. Some experimental data from similar work was used for validation of a simulated model. Some samples were designed and considered with different combined geometries. It was found from simulated model that the most ability of specific energy absorption and crush force efficiency are related to the circle-square sample. For the circle-square sample, the analytic equations for calculating the mean crush force are obtained. The mean crush force result was compared with the result of simulations, showing a good agreement. The multi-objective optimization process for the circle-square structure was performed using non-dominated sorting genetic algorithms for two statuses. The purpose of optimization is to increase the specific energy absorption and to decrease the peak crushing force which causes the increase of crush force efficiency amount. The amount of specific energy absorption in the second status compared to the first status was improved by 17% and the amount of crush force efficiency was improved by 12% after optimization process.LabVIEW implementation of an enhanced nonlinear PID controller based on harmony search for one-stage servomechanism system
https://jcarme.sru.ac.ir/article_1045.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.Influence of Material and Internal Support on the Natural Frequencies of Thin-Walled Cylindrical Tanks
https://jcarme.sru.ac.ir/article_1380.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.Investigation of hot metal gas forming process of square parts
https://jcarme.sru.ac.ir/article_1044.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&deg;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.Experimental investigation of surface crack density and recast layer thickness of WEDMed Inconel 825
https://jcarme.sru.ac.ir/article_1372.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 &mu;m/&mu;m2 and 20.991&mu;m respectively with an error of less than 5%.Analytical and comparative investigations on counter flow heat exchanger using computational fluid dynamics
https://jcarme.sru.ac.ir/article_1120.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-&epsilon; 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.Effect of geometrical parameters on fluid film coefficients in tilting pad journal bearing
https://jcarme.sru.ac.ir/article_1263.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.Numerical modeling of three-phase flow through a Venturi meter using the LSSVM algorithm
https://jcarme.sru.ac.ir/article_1046.html
One of the challenging problems in the Oil &amp; 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 &gamma; and &sigma;^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.Solid-phase effects on the performance of a centrifugal slurry pump using computational fluid dynamics
https://jcarme.sru.ac.ir/article_1230.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&rlm;. 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.Impact of thermal radiation and viscous dissipation on hydromagnetic unsteady flow over an exponentially inclined preamble stretching sheet
https://jcarme.sru.ac.ir/article_1144.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&rsquo;s are rehabilitated into coupled non-linear ODE&rsquo;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.Numerical Study of Transient Behavior and Heat Transfer in a Phase Change Material (PCM) affected by Heat Transfer Fluid (HTF) Flow Parameters
https://jcarme.sru.ac.ir/article_1226.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.The effect of turbulence model on predicting the development and progression of coronary artery atherosclerosis
https://jcarme.sru.ac.ir/article_1177.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-&epsilon; and k-&omega; turbulence models and then compared. According to the results, the negative pressure predicted by the k-&omega; turbulence model was several times greater than that by the k-&epsilon; 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-&omega; model predicted a larger reverse flow region in the post-stenotic region. In other words, the k-&omega; turbulence model predicts a larger part of the post-stenotic region to be prone to disease and the k-&epsilon; turbulence model predicted a higher rate of plaque growth. Moreover, the k-&omega; model predicted a much more intense reverse flow region than the k-&epsilon; model, which itself can lead to blood pressure disease.Tomographic reconstruction of isotropic materials using genetic algorithms with ultrasound time-of-flight projection data
https://jcarme.sru.ac.ir/article_1225.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&rsquo;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.Operational trends of a mini parabolic solar collector for agricultural purposes in a non-active solar environment
https://jcarme.sru.ac.ir/article_1047.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.Simulation of blood flow in the abdominal aorta considering penetration into the organs using pore network model
https://jcarme.sru.ac.ir/article_1223.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.Numerical analysis of heat transfer in helical tube with the aluminum oxide (Al2O3) nano fluid injection in water
https://jcarme.sru.ac.ir/article_1055.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 &ndash;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.Numerical analysis of microchannel based bio-inspired heat sinks with multiple inlet-outlet pairs for cooling square shaped electronic circuits
https://jcarme.sru.ac.ir/article_1219.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.Numerical modeling and comparison study of elliptical cracks effect on the pipes straight and with thickness transition exposed to internal pressure, using XFEM in elastic behavior.
https://jcarme.sru.ac.ir/article_1025.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.Linear thermal radiation effects on MHD viscoelastic fluid flow through porous moving plate with first order chemical reaction, variable temperature and concentration
https://jcarme.sru.ac.ir/article_1218.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.Characteristics of fish oil biodiesel with the impact of diesel fuel addition on a CI engine
https://jcarme.sru.ac.ir/article_1072.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%) &ndash; 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.Research on the Dynamics of a Hydraulic Static-pile-pressing Machine during the Process of Lifting and Slewing of Piles
https://jcarme.sru.ac.ir/article_1217.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&rsquo;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.Experimental study and numerical simulation of three dimensional two phase impinging jet flow using anisotropic turbulence model
https://jcarme.sru.ac.ir/article_902.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.Analysis of Generalized Compressor Characteristic on Surge Phenomena in Axial Compressors
https://jcarme.sru.ac.ir/article_1216.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 solutionParametric study on axial compressor performance in design condition
https://jcarme.sru.ac.ir/article_1024.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.Analysis of chemical reaction and thermophoresis on MHD flow near the accelerated vertical plate in a rotating system with variable temperature
https://jcarme.sru.ac.ir/article_1188.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.Analytical study of induced magnetic field and heat source on chemically radiative MHD convective flow from a vertical surface
https://jcarme.sru.ac.ir/article_1183.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.Numerical analysis of photovoltaic power generation in different locations of Bangladesh
https://jcarme.sru.ac.ir/article_1179.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&deg; 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&deg;C addition of solar cell temperature.Investigation of temperature jump and slip effects on nanofluid treatment inside a vertical annulus via modified Buongiorno’s model
https://jcarme.sru.ac.ir/article_1178.html
In the present work, the study of alumina-water nanofluid heat transfer between two concentric vertical cylinders has been done by modified Buongiorno&rsquo;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 &epsilon; 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.An Experimental and Analytical Investigation of Flange Forming by Spinning Process
https://jcarme.sru.ac.ir/article_1166.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.Finite Element Simulation of Crack Growth Path and Stress Intensity Factors Evaluation in linear Elastic Materials
https://jcarme.sru.ac.ir/article_1161.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.Thermo-mechanical characterization of post-consumer recycled high impact polystyrene from disposable cups: influence of the number of processing cycles.
https://jcarme.sru.ac.ir/article_1160.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.Effect of Shear State on Fracture of Refined Grain Pure Copper
https://jcarme.sru.ac.ir/article_1140.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.Experimental Investigation of EDM Process Parameters by Using Pongamia Pinnata Oil blends as Dielectric Medium
https://jcarme.sru.ac.ir/article_1136.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.Fracture analysis of pre-cracked and notched thin plates using peridynamic theory
https://jcarme.sru.ac.ir/article_1135.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.Thermomechanical behaviour of Functionally Graded Plates with HSDT
https://jcarme.sru.ac.ir/article_1121.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&rsquo;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.Effect of fuel injection pressure of microalgae spirulina biodiesel blends on engine characteristics
https://jcarme.sru.ac.ir/article_1082.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&deg; 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.Effect of axial groove location, length & width ratio on the bearing properties and stability
https://jcarme.sru.ac.ir/article_1071.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.Mechanism of surface generation in grinding of AA6061-TiB2/ZrB2 in-situ composites
https://jcarme.sru.ac.ir/article_1070.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.Heat transfer characteristics of methane-air diffusion flames impinging normally on plane surfaces
https://jcarme.sru.ac.ir/article_1067.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-&epsilon; 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.Analytical study of heat and mass transfer in axisymmetric unsteady flow by ADM method
https://jcarme.sru.ac.ir/article_1066.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.Application of Image-based Acquisition Techniques for Additive Manufacturing using Canny Edge Detection
https://jcarme.sru.ac.ir/article_1062.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.Analysis of Factors Affecting Delamination in Drilling GFRP Composite
https://jcarme.sru.ac.ir/article_1061.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.Experimental Evaluation and Estimation of Frictional Behavior of Polymer Matrix Composites
https://jcarme.sru.ac.ir/article_1060.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.Novel Numerical Solution of Non-linear Heat Transfer of Nanofluid over a Porous Cylinder: Buongiorno-Forchheimer Model
https://jcarme.sru.ac.ir/article_1059.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, &Lambda;, 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.Multi-Objective Particle Swarm Optimization of WEDM Process Parameters for Inconel 825
https://jcarme.sru.ac.ir/article_1058.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 &alpha; value of &plusmn; 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 2.448&mu;m) 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.Application of Combined Mathematical modeling/Optimization Methods Coupled Pitch Controller in Wind Turbine Using Hybrid MLP Neural Network and Firefly Algorithm
https://jcarme.sru.ac.ir/article_832.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.Investigation of natural convection heat transfer of MHD hybrid nanofluid in a triangular enclosure
https://jcarme.sru.ac.ir/article_976.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.