Abstract Theory and computations have established that thermodynamic gradients created by hot spots in reactive gas mixtures can lead to spontaneous detonation initiation. However, the current laminar theory of the temperature-gradient mechanism for detonation initiation is restricted to idealized physical configurations. Thus, it only predicts conditions for the onset of detonations in quiescent gases, where an isolated hot spot is formed on a timescale shorter than the chemical and acoustic timescales of the gas. In this work, we extend the laminar temperature-gradient mechanism into a statistical model for predicting the detonability of an autoignitive gas experiencing compressible isotropic turbulence fluctuations. Compressible turbulence forms non-monotonic temperature fields with tightly-spaced local minima and maxima that evolve over a range of timescales, including those much larger than chemical and acoustic timescales. We examine the utility of the adapted statistical model through direct numerical simulations of compressible isotropic turbulence in premixed hydrogen-air reactants for a range of conditions. We find strong, but not conclusive, evidence that the model can predict the degree of detonability in an autoignitive gas due to turbulence-induced thermodynamic gradients.

中文翻译：

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由可压缩湍流热力学涨落引起的爆轰

摘要 理论和计算已经确定，由反应性气体混合物中的热点产生的热力学梯度可导致自发起爆。然而，目前关于起爆温度梯度机制的层流理论仅限于理想化的物理配置。因此，它仅预测静止气体中爆炸开始的条件，其中在比气体的化学和声学时间尺度更短的时间尺度上形成孤立的热点。在这项工作中，我们将层流温度梯度机制扩展到一个统计模型中，用于预测经历可压缩各向同性湍流波动的自燃气体的爆炸性。可压缩湍流形成具有紧密间隔的局部最小值和最大值的非单调温度场，它们在一系列时间尺度上演化，包括远大于化学和声学时间尺度的那些。我们通过在一系列条件下对预混氢-空气反应物中的可压缩各向同性湍流进行直接数值模拟来检查调整后的统计模型的效用。我们发现了强有力但并非决定性的证据，表明该模型可以预测由于湍流引起的热力学梯度而导致的自燃气体的爆炸程度。