旋流预混燃烧室流动混合的大涡模拟

采用大涡模拟的方法研究旋流预混燃烧室中的流动及燃料空气混合过程,选取亚格子湍动能模式为基准的涡黏模型,通过模拟涡核的运动过程定性的表征了拟序结构的发展;引入混合不均匀度的概率密度函数,研究入口边界条件尤其是入口速度对于涡团破碎及混合程度的影响规律;通过研究速度分量与燃料质量分数脉动的相关性,分析了不同方向的速度脉动对于混合过程的影响因子.这些均为进一步研究旋流预混燃烧室的燃烧不稳定性及污染物排放提供了理论上的指导. 

Flow and air-fuel mixing processes in a premixed swirl combustor with LES

Flow and air-fuel mixing processes in a premixed swirl combustor were studied with large eddy simulation (LES) method.Eddy viscosity model based on SGS(subgrid scale) turbulent kinetic energy model was selected to simulate the movement of vortex core,in order to characterize the qualitative development of coherent structures;with the introduction of unmixedness probability density function,the influences of inlet boundary conditions on eddy break-up and mixing were studied,especially the inlet velocity boundary condition;the correlation between velocity components and fuel mass fraction fluctuation shows the different velocity fluctuation factors for the mixing process.These conclusions provide useful information for further studying of premixed swirl combustor instability and pollutant emissions.