预混气爆轰马赫反射实验研究

Experimental Studying on Mach Reflection of Detonation Wave of Premixed Mixtures

关键词:  气相爆轰  马赫反射  爆轰不稳定性  胞格结构  活化能

Key words:  Gaseous detonation  Mach reflection  Detonation instability  Cellular structure  Activate energy

摘要:

为研究斜爆轰马赫反射的实验现象以及不稳定性对马赫反射的影响，在矩形爆轰管道中，对3种预混气的马赫反射现象进行了实验研究，取得烟膜记录。烟膜结果显示，三波点高度在楔角附近与无反应三激波理论类似，随后逐渐偏向反应三激波理论，三波点实际高度由反应实际放热量决定，三种气体偏转始末距离与结束偏转距离之比平均值分别为0.42，0.49，0.31，与三者活化能大小关系相符合。胞格结构随初始压力增大而渐趋规律，胞格尺寸也逐渐减小，由CJ区域到过驱区域胞格结构存在明显的转变。横波是影响斜爆轰稳定的重要因素，压力增大可抑制分子的无规则运动，使横波出现的位置更加集中，胞格更为规律。预混气爆轰不稳定度大的气体横波出现的时空位置更不易确定，胞格结构更不规律，胞格尺寸较小。

Abstract:

In order to study the Mach reflection of oblique detonation wave and the influence of instability on Mach reflection，three premixed mixture with different quantitative instability were investigated in a rectangular channel. The smoked foils were used to obtain the experimental results. The results clarified that the height of triple point was similar with the non-reactive three shock theory near the apex，but in far field，it turned to deflect to the reactive three shock theory. In fact，practical reactive heat determines the height of Mach stem，while it is related to the activate energy of three premixed mixture that the ratio of the distance between the triple point trajectory begins and ends deflection to the distance where the triple point ends deflection is 0.42，0.49，0.31，respectively. With the initial pressure increasing，the cellular structure became more regular and the size became smaller. Also，the cellular structure transited apparently from CJ zone to overdriven zone. Transverse wave can be considered as a main influence factors on oblique detonation. Increasing pressure can reduce the molecule random movements so that the position where the transverse wave forms became more concentrated. It lead to the cellular structure becoming more regular as well. What’s more，higher instability of premixed mixtures result in more difficulty of determination of the transverse wave forming position in space and time，higher irregularity of cellular structure and smaller cell size.