关键词: 湍流, 反应动力学, 数值模拟, 反应机理简化, 反应-扩散流形, 大涡模拟, 分层火焰, 假定滤波密度函数

Abstract:

A recently developed method for reducing reaction mechanism, the reaction-diffusion manifolds (REDIM) method, is combined with the presumed filtered density function (PFDF) to construct a new sub-grid scale (SGS) combustion model for large eddy simulation (LES) of turbulent combustion. Unlike its predecessor intrinsic low-dimensional manifolds method, the REDIM method takes into account the coupling of reaction and molecular transport processes explicitly, so it is capable of describing fast reaction regions as well as regions where chemical kinetics are slow and diffusion governs the overall process. Because of this advantage of REDIM, the new SGS combustion model is theoretically capable of simulating turbulent partially premixed flames and stratified flames, in which reaction and diffusion processes are both important. For validating its performance, the new model is employed to simulate the benchmark Darmstadt turbulent stratified flame (TSF). First, a grid resolution study is conducted by computing isothermal flow field with two grids. Then the finer grid is used to simulate a turbulent flame with stratified effect. The overall good agreement of the statistics of velocity, temperature and species with the experimental data demonstrates the capability of the LES method and the REDIM-PFDF model for dealing with TSF. More simulations for other Darmstadt TSF cases are still ongoing, to obtain a deeper insight of the complex chemistry-physical process in the TSF combustion.

Key words: turbulent flow, reaction kinetics, mathematical modeling, reaction mechanism, reaction-diffusion manifolds, large eddy simulation, stratified flame, presumed FDF