混合時間スケールSGSモデルを用いたエンジン定常吸気流のLES

抄録

Large eddy simulation (LES) using a mixed-time-scale (MTS) SGS model is applied to the intake flows in simplified internal combustion engine geometry. A modified colocated grid system is employed so as to perform calculations stably with a central difference scheme for convection terms. The results are compared with corresponding experimental data and the computational results obtained by using the low-Reynolds-number linear k-εand cubic nonlinear k-ε-A₂ turbulence models. The LES results show the best agreement with experimental data in three computational cases, not only in the mean velocity profiles but also in the profiles of turbulent energy. These results suggest that LES using the MTS SGS model is an effective method for accurately predicting the performance of a combustion engine involving turbulent diffusion of spray and combustion flame. In addition, the results are compared with those obtained by a quasi-direct simulation employing the QUICK scheme for the convection term and no turbulence model. It is clarified that the numerical viscosity from the QUICK scheme has a great influence on the computational results and decreases the prediction accuracy.