气相爆轰波胞格尺度与点火延迟时间关系研究

讨论点火延迟时间和爆轰波胞格尺度的内在关系,将点火延迟时间作为特征参量来模拟胞格尺度. 分别对两个总包单步化学反应模型和一个基元反应模型的点火延迟时间进行了数值模拟研究. 对于满足当量比的氢气/空气混合气体,分析了不同初始压力下点火延迟时间随初始温度的变化关系. 研究表明:总包单步反应模型的点火延迟时间不随压力变化,且与初始温度呈线性关系. 基元反应模型的点火延迟时间随压力变化,而且存在理论上的S 型曲线,但是在拐点区域和低温区域与CHEMKIN 计算的结果相差1~3 个量级. 现有模型模拟的胞格尺度普遍偏小,其相应的点火延迟时间也偏小,胞格尺度与点火延迟时间具有正相关性. 入射激波后的气体的点火延迟时间与三波点的运动周期一致,是定量化模拟胞格的关键因素. 

STUDY ON THE RELATIONSHIP BETWEEN IGNITION DELAY TIME AND GASEOUS DETONATION CELL SIZE

In this paper, the intrinsic relationships between ignition delay times and the detonation cell size are analyzed, simulated from two one-step chemical kinetic models and one detailed chemical kinetic model. Ignition delay time for mixtures of hydrogen and air at 0.1MPa and 1.01MPa over the temperature range 800K to 1500K is investigated. The results demonstrate that the ignition delay time for one-step chemical kinetic model is independent of pressure, and linearly correlated with the initial temperature. The ignition delay time for the detailed chemical kinetic model is dependent of pressure, and is not linearly correlated with the initial temperature. However, in the inflection zone and the low temperature zone, the CFD results are 3 orders of magnitude smaller than the theoretical values. The CFD values of the ignition delay time differ from the theoretical ones by a factor as large as 103. The detonation cell size simulated by all the chemical models is smaller than the experimental results, and the ignition delay time is proportional to the cell size. The detonation simulation results show that the longer the ignition delay time, the bigger the detonation cell size. The period of triple-point is almost equal to the ignition delay time of the gas behind the incident shock wave. Ignition delay time is a key parameter in detonation initiation and propagation.