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The present work aims at improving the predictive capabilities of quasi-dimensional combustion models for fast and accurate automated design of spark engines. The models are based on mass and energy conservation principles supplemented by sub models based on experimental correlations. Here, we improve the accuracy of the classical two-zone model by means of two successive modifications. First, we generate a three-zone model by introducing a reacting zone near the walls. In the third zone, the gases burn at a lower temperature than in the main reacting zone, due to heat losses to the walls. Secondly, a multi-zone model is built by dynamically adding new reacting zones at given crank-angle intervals. The use of multiple zones allows to take into account temperature and concentrations gradients in the flame.

RENAULT has developed a numerical method for predicting the efficiency of two types of oil separator. Numerical simulation is performed with the CFD package FLUENT6. Blow-by flow is considered as an aerosol mixture and is simulated as a continuous phase (air flow) carrying a discrete phase (oil droplets). The separator is meshed using a uniform 1mm tetrahedral mesh. The inlet volume flow is assumed steady. A standard k-epsilon model is used for flow calculation. Then droplets are introduced and their trajectories are computed. The wall boundary condition is straightforward: a particle touching a wall is assumed trapped and removed from the flow. The experimental set-up for efficiency measurement includes an oil generator which produces an air/oil aerosol mixture with a user-fixed volume flow, oil mass-flow and oil droplets diameter distribution. The generator is connected to a prototype oil separator. It is equipped with length and position-adjustable plates.