Search Results

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.

The meaningfulness of numerical studies on Wankel engine flow fields depends strongly on turbulence modelling and the numerical methods used to obtain solutions. This investigation examined two different turbulence models and several variations of a numerical method for calculating turbulent flow fields inside one of the combustion chambers of a motored, two-dimensional Wankel engine. The two turbulence models examined were the standard k-ε model with wall functions and the low Reynolds number k-ε model of Chen and Patel. The numerical method used in this investigation was the approximate-factorization method of the ADI type with upwind differencing of the convection terms based on flux-vector splitting.