A Numerical Study on the Effects of Apex Seal Leakage on Wankel Engine Flow Fields

A numerical study was conducted to examine how leakages across apex seals affect the flow field in one combustion chamber of a motored, two-dimensional, Wankel rotary engine. Results are presented which show the effects of engine speed, leakage area, and compression ratio on velocity field, distribution of turbulent kinetic energy, and volume-averaged pressure when there are apex seal leakages. These results indicate that apex seal leakages can have a significant effect on the flow field.

This numerical study is based on the density-weighted-ensemble-averaged continuity, “full compressible” Navier-Stokes, and total energy equations, closed by a k-ε model of turbulence with wall functions. The numerical method used to obtain solutions was the approximate factorization algorithm of the ADI type. All convection terms were treated by second-order accurate upwind differencing through flux-vector splitting. All diffusion terms were treated by second-order accurate central differencing.