剪切层强度对湍流分层火焰传播特性的影响

Effect of Shear Layer Strength on Turbulent Stratified Flame Propagation Characteristics

采用REDIM-PFDF模型对Darmstadt湍流分层火焰进行了大涡模拟,分别计算了有分层无剪切效应的状态(A-r)和有分层有剪切的状态(C-r),研究分析了分层剪切效应对于湍流分层火焰传播机制的影响.重点对反应层与混合层的交叉角?变化情况进行了详细分析.结果发现,A-r和C-r均以焰后支持火焰传播模式为主,但由于C-r中增加了很强的剪切效应,导致湍流增强,分层效应被弱化,促进了燃料混合,出现焰前支持火焰传播模式的概率有所增加.

Large eddy simulations of Darmstadt turbulent stratified flames were performed using the REDIMPFDF model,aiming to investigate the effect of shear layer strength on the propagation characteristics of turbulent stratified flames.Two flame cases,case A-r with stratification and weak shear and case C-r with stratification and strong shear,were simulated.The variation of alignment angle between the reaction layer and the mixing layer was analyzed in detail.It was shown that both A-r and C-r cases were mainly controlled by ‘back-supported＇ flame propagating mode.However,due to the strong shear effect in C-r,the enhanced turbulence promoted a faster mixing of fuel and air,which resulted in a weakened stratification,and increased the probability for ‘frontsupported＇ flame propagating mode.