EVAPORATION HEAT LOSS IN THE FLAMELET MODEL FOR DILUTE SPRAY FLAMES

摘要

The motivation of this paper is to extend the flamelet/progress variables (FPV) approach used successfully in gaseous flames to spray combustion. To consider the evaporation heat loss effect in the FPV approach, two new methods are proposed. One is to correct the gaseous temperature in the flamelet calculation, and the other is to couple this heat loss into the CFD process. To evaluate their performance, the piloted ethanol-air spray flames are simulated by LES in the Eulerian-Lagrangian framework. The simulation results using these two methods and some other existing models are compared with experimental data. It is shown that both methods give lower gaseous temperature compared to the conventional FPV approach and the mean gaseous temperature is closer to the experimental data especially downstream and near the centerline. As to other statistical results (e.g., the mean velocities and rms velocities and SMD), these methods show similar profiles which are all in good agreement with experimental data. The conclusion is that our models can give a good account of the evaporation heat loss. Meanwhile, much lower computational costs are needed compared to the method of solving the enthalpy equation.