Role of reactivity gradients in the survival, decay and reignition of methane-air detonations in large channels
Role of reactivity gradients in the survival, decay and reignition of methane-air detonations in large channels
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DOI：
10.1016/j.combustflame.2020.08.034
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发表时间：
2020-12
影响因子：
4.4
通讯作者：
Praveen Honhar;C. Kaplan;R. Houim;E. Oran
中科院分区：
文献类型：
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作者：
Praveen Honhar;C. Kaplan;R. Houim;E. Oran
本文研究了反应性梯度对爆轰传播的影响，在一个相对较大的（~ 1米高）的通道，通过研究爆轰传输从化学计量的甲烷和空气的混合物的贫燃料。数值模型求解完全可压缩的反应Navier-Stokes方程。的化学热释放，质量扩散和物种生产率建模的化学扩散模型（CDM），校准再现火焰和爆轰性能在一个范围内的当量比的新版本。一维和二维模拟进行三种不同的反应性梯度，对应于一个陡峭的，中间的，和浅的反应性梯度。在一维中，爆轰传播通过所有反应性梯度导致爆轰失败，因为爆轰波阵面折叠成冲击波和火焰。在二维情况下，情况并非如此，在二维情况下，由于横波的存在以及与之相关的冲击碰撞，爆轰传播和失效的动力学要复杂得多。爆轰波在两个维度上的成功传播取决于反应性梯度的陡度、爆轰波的局部强度以及爆轰波与泰勒膨胀扇的相互作用。在多维空间中，爆炸较弱的部分解耦成分离的激波和火焰，但波前的过驱动部分幸存下来。其结果是部分失败在前面。然而，这种部分失效的爆轰会在其反应区产生极高压力的过驱动横向爆轰。
This paper examines the effect of gradients in reactivity on the propagation of detonations in a relatively large ( ~ 1 m high) channel by studying detonation transmission from stoichiometric to fuel-lean mixtures of methane and air. The numerical model solves the fully compressible, reactive Navier–Stokes equations. The chemical heat release, mass diffusion and species-production rates are modeled by a new version of the chemical-diffusive model (CDM), calibrated to reproduce flame and detonation properties over a range of equivalence ratios. One- and two-dimensional simulations are performed for three different reactivity gradients, corresponding to a steep, intermediate, and shallow gradient in reactivity. In one dimension, detonation transmission across all reactivity gradients results in detonation failure, as the detonation wavefront decouples into a shock and a flame. This is not the case in two dimensions, where the dynamics of detonation transmission and failure are far more complex due to the presence of transverse waves and the shock collisions associated with them. Successful transmission of the detonation in two dimensions depends on the steepness of the reactivity gradient, the local strength of the detonation, and the interaction of the detonation with the Taylor expansion fan. In multidimensions, weaker parts of the detonation decouple into separated shocks and flames, but the overdriven parts of the wavefronts survive. The result is partial failure at the front. Such partially failed detonations, however, can develop extremely high pressure overdriven transverse detonations in their reaction zones.