Thermodynamics and Cumbustion
M. Zakyani
Abstract
The paper presents the large eddy simulation conditional moment closure (CMC) simulation of pilot stabilized methanol flame to study the effects of conditional scalar dissipation rate (CSDR). Two models are used in this research to evaluate CSDR: conditional volume averaging (CVA) and amplitude mapping ...
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The paper presents the large eddy simulation conditional moment closure (CMC) simulation of pilot stabilized methanol flame to study the effects of conditional scalar dissipation rate (CSDR). Two models are used in this research to evaluate CSDR: conditional volume averaging (CVA) and amplitude mapping closure (AMC). For the turbulence modelling, the dynamic Smagorinsky approach is adopted to allow for local adjustment of the Smagorinsky constant. CMC is used for turbulent combustion modeling. CVA is adopted for the calculation of conditional velocity. The temperature, mixture fraction, and major species mass fraction are compared against experimental data along radial direction for both cases. The comparison showed reasonable agreement with the experimental measurements for the temperature. It is also observed that the AMC model is superior in predictions compared to the CVA method. Additionally, carbon monoxide and carbon dioxide are predicted with remarkable accuracy. Moreover, the conditional temperature is also in good agreement with experimental data that shows CMC model capabilities in turbulent combustion modeling.
M. Zakyani
Abstract
Large eddy simulations of non-reactive Delft II and Sydney bluff body flow are performed using different sub-grid scale models. Simulation of non-reactive burners is useful when studying flow characteristics inside reactive burners. As turbulent combustion simulation is rather an intricate task, it is ...
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Large eddy simulations of non-reactive Delft II and Sydney bluff body flow are performed using different sub-grid scale models. Simulation of non-reactive burners is useful when studying flow characteristics inside reactive burners. As turbulent combustion simulation is rather an intricate task, it is helpful to study cold air flow inside the combustion chamber before igniting the chamber. In order to study the flow inside the mentioned test cases, different sub-grid scale models, i.e., constant Smagorinsky, dynamic Smagorinsky and dynamic WALE model are used to model the unresolved small scales. For the numerical simulations, a finite volume in-house code is used. The code adopts the projection method to solve the fluid flow equations. A second-order accurate scheme is used for spatial discretization. The time integration is done using a second-order accurate predictor-corrector scheme. For solving the resultant pressure Poisson equation, TDMA (Tridiagonal Matrix Algorithm) is used with multi-grid convergence acceleration. Generally, the results show good agreement with available experimental data. As expected, the dynamic WALE model performs better than the other models. To further improve the results, a rather realistic type of velocity inlet boundary conditions are applied to Sydney bluff body flow, i.e., digital filter velocity inflow boundary conditions. The results show drastic improvement using digital filter inflow, which is mainly due to the turbulent nature of the flow field.
