Deflagration-to-Detonation Transition in Highly Reactive Combustible Mixtures
Deflagration-to-Detonation Transition in Highly Reactive Combustible Mixtures
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DOI：
10.1016/j.actaastro.2010.05.024
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发表时间：
2010-10
期刊：
影响因子：
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通讯作者：
M. Liberman;M. F. Ivanov;A. Kiverin;Mike Kuznetsov;A. Chukalovsky;T. Rakhimova
中科院分区：
文献类型：
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作者：
M. Liberman;M. F. Ivanov;A. Kiverin;Mike Kuznetsov;A. Chukalovsky;T. Rakhimova
本文对高活性氢氧和乙烯氧混合气体的爆燃转爆轰(DDT)过程进行了实验、理论和数值研究。对氢氧混合气体的二维反应N-S方程进行了数值求解，该方程考虑了粘度、热传导、分子扩散和详细的化学反应机理的影响。结果表明，DDT的机理完全由无滑移管内火焰加速的特性决定。实验和计算表明，这个过程有三个不同的阶段：(1)火焰以指数形式加速，在远离火焰的地方产生激波；(2)火焰加速度减小，激波直接在火焰表面形成；(3)实际转变为爆轰的最后第三个阶段。在第二阶段，在火焰前方形成一个压缩和加热的未反应气体口袋--预热区，进入火焰的压缩未反应混合物产生较大幅度的压力脉冲。压力的增加提高了反应速度，由于压力峰和反应之间的正反馈，压力峰呈指数增长，陡峭成强激波，与形成过驱动爆轰波的反应区耦合。提出的DDT新的物理机制突出了无滑移壁管内火焰加速的特点，这是DDT产生的关键因素。
The paper presents experimental, theoretical, and numerical studies of deflagration-to-detonation transition (DDT) in highly reactive hydrogen–oxygen and ethylene–oxygen mixtures. Two-dimensional reactive Navier–Stokes equations for a hydrogen–oxygen gaseous mixture including the effects of viscosity, thermal conduction, molecular diffusion, and a detailed chemical reaction mechanism are solved numerically. It is found that mechanism of DDT is entirely determined by the features of the flame acceleration in tubes with no-slip walls. The experiments and computations show three distinct stages of the process: (1) the flame accelerates exponentially producing shock waves far ahead from the flame, (2) the flame acceleration decreases and shocks are formed directly on the flame surface, and (3) the final third stage of the actual transition to a detonation. During the second stage a compressed and heated pocket of unreacted gas adjacent ahead to the flame—the preheat zone is forming and the compressed unreacted mixture entering the flame produces large amplitude pressure pulse. The increase of pressure enhances reaction rate and due to a positive feedback between the pressure peak and the reaction the pressure peak grows exponentially, steepens into a strong shock that is coupled with the reaction zone forming the overdriven detonation wave. The proposed new physical mechanism of DDT highlights the features of flame acceleration in tubes with no-slip walls, which is the key factor of the DDT origin.