Recent Progress in Turbulent Combustion Modeling of Spray Flames Using Flamelet Models

Abstract

The application of liquid fuels for a wide range of engineering applications has motivated the development of predictive CFD models for spray flames. The coupling of multiphase spray physics along with turbulence and complex chemistry of combustion poses a huge challenge to computational models in terms of accuracy and cost. The models need to accurately capture the spray breakup, evaporation, mixing and the accompanying chemistry along with turbulence chemistry interaction effects accurately in order to be predictive. Flamelet-type combustion models decouple the fluid flow from the chemistry and have significantly reduced computational costs. This framework can capture the effects of turbulence chemistry interactions and include large chemistry mechanisms without significantly increasing the computational costs. The flamelet concept also enables the a priori tabulation of flamelets which can further speed up computational models. The Eulerian-Lagrangian spray model coupled with the flamelet type combustion models have been used extensively to model spray flames in a wide range of applications like reciprocating engines, gas turbines and furnaces. This chapter discusses the theory and application of such modeling approaches in RANS and LES along with some latest flamelet solver developments which now enable the use of detailed chemistry mechanisms for higher hydrocarbon fuels without reduction.