浓度梯度对火焰加速和爆燃转爆轰的影响

Effects of Composition Gradient on Flame Acceleration and Transition to Detonation

本文采用高精度CFD方法求解非定常、完全可压缩的反应性Navier-Stokes方程,并开发了非均匀氢–空气爆燃转爆轰(DDT)的简化燃烧反应模型,以研究浓度梯度对氢–空气火焰加速和DDT的影响。并将危险性最大(化学计量比)的均匀混合物与整体当量比为1的非均匀混合物进行比较。结果表明,虽然非均匀混合物最大火焰表面积较大,但平均总释热较低、火焰加速较弱,导致两者的DDT机理和发生位置均不同,爆轰波更易解耦。本文条件下,化学当量比的均匀混合物比非均匀混合物更易发生DDT,主要是因为其总释热更高。

In this paper, the unsteady, fully compressible, reactive Navier-Stokes equations were solved by high-order CFD method to study the effect of composition gradient on the flame acceleration and deflagration to detonation transition(DDT) in a mixture of hydrogen and air. A simplified chemical-diffusive model was developed for non-uniform hydrogen-air mixture. The homogeneous mixture with the highest risk(stoichiometric ratio) was compared with the inhomogeneous mixture with a global equivalence ratio of 1. The results show that although the maximum flame surface area of the inhomogeneous mixture is large, the average total heat release is low and the flame acceleration is weak, which leads to different DDT mechanism and location, and the detonation wave is more easily decoupled. In this paper, DDT is more likely to occur in homogeneous mixtures with stoichiometric ratio than in inhomogeneous mixtures, mainly because of the higher total heat release.