甲烷平面射流扩散火焰的大涡模拟

LES OF METHANE-AIR PLANAR JET DIFFUSION FLAME

本文对甲烷-空气平面自由射流扩散火焰进行了大涡模拟,采用分步投影法求解动量方程,湍流亚格子项采用动态模式模拟,化学反应速率亚格子项采用动态相似模式模拟,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。模拟结果给出了湍流扩散火焰的瞬态发展变化过程,表明射流扩散火焰的发展过程存在着“湍流控制”和“化学反应控制”两个不同阶段。 “湍流控制”阶段仅存在于火焰发展初期的极短时间内。

In this paper, LES of methane-air planar jet diffusion name is performed. The momentum equations are solved by a projection method. A dynamic model is applied for the turbulent sub-grid scales. The SGS term of reaction is simulated by a dynamic similarity model. Buneman variant of cyclic odd-even reduction algorithm is adopted for solving the pressure Poisson equation. The mechanism of a simplified 4-step chemical kinetics is applied for the methane-air reaction. Simulation results give satisfactorily description of the transient evolution process of a diffusion jet flame, as well as the vortex-flame interactions. It is found that the development of a jet flame consists two distinct phases named by the authors as the 'turbulence-dominated phase' and the 'reaction-dominated phase'. The 'turbulence-dominated phase' exists only for a very short time at the initial period of the flame.