平面自由射流中燃料扩散的大涡模拟

Large Eddy Simulations of Fuel Diffusion in Plane Jets

对甲烷 -空气预混气体的平面自由射流进行了大涡模拟 ,采用分步投影法求解动量方程 ,亚格子项采用标准 Smagorinsky亚格子模式模拟 ,压力泊松方程采用修正的循环消去法快速求解 ,空间方向采用二阶精度的差分格式 ,在时间方向上采用二阶精度的显式差分格式。模拟结果给出了预混气体射流中拟序结构对燃料扩散的影响 ,表明促使燃料扩散的主要因素是射流中的拟序结构 。

The-two-dimensional spatially developing plane jet of pre-mixed gas of methane-air is simulated by large eddy simulation. The governing equations are solved with Chorin's fractional-step projection method. The standard Smagorindsky sub-grid model is used to model the motions of small-scale structures. The 2nd order accuracy finite difference scheme is used in space direction, and the 2nd order accurate Adams Bashforthe scheme for the time integration. The result of simulation shows how the coherent structures affect diffusion of fuel in the jet, and the idea that the most important factor affecting fuel diffusion in jet is not the concentration gradient but the coherent structures is also proved in this paper.