Understanding detonation development from a flame kernel initiated by a pre-ignition event is important for modern internal combustion (IC) engines operating at boosted conditions. To provide fundamental insights into the effects of bulk gas temperature stratification on the characteristics of detonation development, one-dimensional high fidelity simulations were conducted for a constant volume reactor filled with a thermally stratified reactive stoichiometric hydrogen/air mixture. A linear temperature variation in the upstream end-gas was introduced to represent the thermal stratification of the bulk mixture, and the evolution from the initial deflagration flame front to detonation development was examined. The results showed that the bulk-gas temperature gradient has a significant effect on the run-up time and intensity of the developing detonation. Detailed analyses further revealed that the mechanism of detonation development is qualitatively different for the positive and negative temperature gradient cases. In the former, the detonation development is initiated by the end-gas autoignition at the wall, while the latter exhibits detonation development following the process of the self-acceleration of the flame similar to the deflagration-to-detonation transition. This behavior is attributed to the longer residence time in the end-gas allowing the reinforcement by the interaction of incident and reflected pressure waves during the flame propagation, and results in the peak pressure even higher than the case with the same level of positive temperature gradient. Furthermore, yet another detonation development pattern was observed for the negative temperature gradient condition in the presence of a uniform temperature region just ahead of the flame. In this case, autoignition was found to start in the middle of the bulk end-gas, and subsequently leads to the transition to detonation. The results demonstrate the importance of the bulk gas conditions in predicting the detonation development, which corroborate the existing theoretical framework.

了解由点火前事件引发的火焰核引起的爆炸发展，对于在增压条件下运行的现代内燃机（IC）至关重要。为了提供基本的见解，以了解整体温度分层对爆炸发展特征的影响，对填充有热分层反应化学计量氢/空气混合物的恒容反应堆进行了一维高保真度模拟。引入上游端气的线性温度变化来表示本体混合物的热分层，并研究了从初始爆燃火焰前沿到爆炸发展的演变过程。结果表明，散气温度梯度对起爆时间和爆炸起爆强度有重大影响。详细的分析进一步表明，在正负温度梯度情况下，爆炸发展的机理在质量上是不同的。在前者中，爆炸的产生是由壁上的末端气体自燃引发的，而后者在火焰自加速过程之后表现出的爆炸发展，类似于爆燃-起爆过渡。这种现象归因于在最终气体中的停留时间更长，从而在火焰传播过程中通过入射压力波和反射压力波的相互作用而得以增强，并且导致峰值压力甚至比具有相同水平的正温度梯度时的峰值压力还要高。 。此外，在火焰正前方存在均匀温度区域的情况下，在负温度梯度条件下还观察到了另一种爆炸发展模式。在这种情况下，发现自燃始于散装尾气的中间，随后导致向爆炸的过渡。结果表明，大量气体条件在预测爆炸发展中的重要性，证实了现有的理论框架。