Numerical simulation of the small vortices in the intake and compression processes of an engine

The turbulence-generating mechanism in the intake and compression processes of an engine with a square cylinder is investigated by performing a three-dimensional numerical simulation. Emphasis is placed on the influences of the intake turbulence and the compression effect on the TDC (Top Dead Center) turbulence. The compressible Navier-Stokes equations are solved without any explicit turbulence models. The employed numerical algorithm is an extended version of the ICE method, and the third-order upwind scheme is employed for the convective terms. The obtained computational results agree well with the experimental visualization using freon as the working fluid under the condition with a Mach number in excess of 0.5. It is shown that the drastic transition to turbulence near TDC is grasped by computations using this numerical method.