ASSESSMENT OF TURBULENT COMBUSTION SUBMODELS USING THE LINEAR EDDY MODEL

Linear Eddy Model (LEM) simulations are conducted in order to study tu rbulence-chemistry interactions in a homogeneous, incompressible, stat ionary turbulent flow with non-premixed reactants. The chemical kineti cs model used in this work involves single- and multi-step, reversible and irreversible isothermal reactions. The simulation results are emp loyed to investigate flame structure and statistics and comparisons ar e made to several other turbulent combustion models. Specifically, com parisons of the LEM results to predictions obtained from the Stationar y Laminar Flamelet Model (SLFM) and the Conditional Moment Closure (CM C) method are presented. The results show qualitative trends similar t o those of previous Direct Numerical Simulations (DNS) for simpler che mistry and provide insights into several key modeling assumptions. For the chemistry under consideration and within the context of compariso ns to the LEM simulation results: (1) SLFM predictions agree better wi th the LEM results for larger values of the scalar dissipation rate, ( 2) the effect of neglecting conditional fluctuations on the chemical s ource terms in the CMC formulation is negligible, (3) CMC accurately p redicts intermediate species and (4) CMC predictions are sensitive to the closure model selected for the conditional scalar dissipation.