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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.

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.

A two-dimensional, implicit finite-difference method of the control-volume variety, a two-equation model of turbulence, and a discrete droplet model have been used to study the flow field, turbulence levels, fuel penetration, vaporization and mixing in Diesel engine-type environments. Good agreement with the droplet penetration data of Hiroyasu and Kadota has been obtained for a range of ambient pressures neglecting the effects of void fraction, droplet coalescence and droplet collisions in the simulation. The model has also been used to study the effects of the intake swirl angle on the flow field, turbulence levels, fuel penetration, vaporization and mixing in a two-stroke Diesel engine operating under motored conditions. Numerical simulations indicate that as the intake swirl angle is increased, the fuel penetration, vaporization and mixing increase.