Towards Large Eddy Simulation of a Turbulent Nonpremixed Jet Flame using the Filtered Mass Density Function Approach

摘要

Progress towards implementation and application of the large eddy simulation (LES)/filtered mass density function (FMDF) approach for turbulent nonpremixed flame prediction is reported. Specifically, a Lagrangian Monte Carlo solution for the transported joint scalar FMDF is combined with a high-fidelity compressible Navier-Stokes equation-based parallel LES code. One of the main obstacles of this approach is related to the inability of the mixing model to produce notional particle transport statistics that mimic the joint FMDF. In particular, the assumption of a constant mechanical-to-scalar time scale ratio and the neglect of the effect of chemical reactions on the scalar time scale, and hence mixing frequency, currently precludes accurate prediction of flame extinction and reignition events. Preliminary results are presented for a non-reacting fully-turbulent jet obtained using several popular mixing models. In addition, progress towards implementing additional mixing models, solving multi-scalar mixing applications, and including reacting flow capabilities will be discussed.