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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.

A computer program -- LeRC3D.Wankel -- was developed to study the flow, spray, and spray combustion in the combustion chambers of Wankel rotary engines. LeRC3D. Wankel is based on an Eulerian-Lagrangian formulation. The gas phase was modelled by an Eulerian approach using the density-weighted, ensemble-averaged conservation equations of mass, momentum (full compressible Navier-Stokes), total energy, and species, closed by a low Reynolds number k-ε turbulence model. The liquid phase, made up of fuel droplets, was modelled by using a Lagrangian approach in which droplet groups are tracked in time. The combustion process which takes place after fuel droplets evaporate and mix with the surrounding air was assumed to be chemical kinetics controlled via a two-step global mechanism. This paper describes the formulation employed in the computer program as well as the essence of the numerical method used to generate solutions. Some computed solutions for the flow field are also presented.