Abstract In the present study, direct detonation initiation by a point energy source in a rich H2–NO2/N2O4–Ar mixture has been investigated using high-resolution one-dimensional numerical simulations performed with detailed chemistry. In particular, the effect of the 2-step energy release profile on the critical initiation energy and the dynamics of the failure process has been studied for the first time. Three reduced reaction models exhibiting a similar first step of energy release but a second step of different strengths have been employed. As the second step of heat release is strengthened, the overall behavior gets closer and closer to a 1-step process. It was found that the critical initiation energy for successful detonation initiation decreases as the second step of heat release is strengthened and the width of the overall heat release pulse is reduced. This feature has been investigated by studying the competition between chemical heat release and unsteadiness along the path of Lagrangian particles. The decrease of the critical initiation energy for stronger second step of heat release seems to be a result of the decrease of the sensitivity of this second step to unsteadiness-induced quenching behind a decaying shock wave. In view of the present results and previous experimental observations on propagating and diffracting detonation in H2–NO2/N2O4(–Ar) mixtures, it seems that the 2-step energy release presenting the specific characteristics observed in rich H2–NO2/N2O4(–Ar) mixtures, i.e. a strong and rapid first step and a weak and slow second step, constitutes a feature which is not essential for detonation propagation but makes detonation direct initiation and transmission to open space more difficult.

中文翻译：

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两步能量释放对富 H2-NO2/N2O4 混合物中点能源直接起爆的影响

摘要 在本研究中，使用具有详细化学性质的高分辨率一维数值模拟研究了在富 H2-NO2/N2O4-Ar 混合物中由点能源引发的直接爆轰。特别是，首次研究了两步能量释放曲线对临界起始能量和失效过程动力学的影响。三个简化的反应模型表现出类似的第一步能量释放，但采用了不同强度的第二步。随着第二步放热的加强，整体行为越来越接近于1步过程。发现成功起爆的临界起爆能量随着第二步放热的加强和整体放热脉冲宽度的减小而降低。通过研究化学放热与拉格朗日粒子路径上的不稳定性之间的竞争，已经研究了这一特征。更强的第二步热释放的临界起始能量的降低似乎是第二步对衰减冲击波后不稳定引起的淬火的敏感性降低的结果。鉴于目前的结果和先前关于在 H2–NO2/N2O4(–Ar) 混合物中传播和衍射爆轰的实验观察，似乎 2 步能量释放呈现出在富 H2–NO2/N2O4(– Ar) 混合物，即