气相爆轰波马赫反射非自相似性特征的实验

Experiment on non-self-similar of Mach reflection of gaseous detonation wave

为了研究在CJ(Chapman-Jouguet)状态下气相爆轰波马赫反射的非自相似性特征,搭建了由驱动段、传播段以及观测段组成的矩形管道;利用纹影和烟膜实验方法分别对3种预混气发生马赫反射现象进行了实验研究.实验结果表明:对稳态或非稳态气体,测量了马赫反射三波点位置高度,验证了马赫反射三波点轨迹线为波动的曲线,即自相似性对爆轰波马赫反射失效;非自相似性的重要特征是三波点轨迹线在楔角初始位置时基本遵循无反应冲击波理论计算结果,随后逐渐偏离并向有反应冲击波转变,之后接近平行于反应冲击波理论计算并稳定地处于两个理论值之间.最后给出在初始压力为10kPa和楔角为30°的条件下,对于所研究的3种气体,其马赫反射三波点发生转变的位置高度分别约为0.8,1.05cm以及0.5cm,可见相同初始条件下非稳态气体的马赫反射发生转变比稳态气体提前.

In order to study the non-self-similarity of Mach reflection of detonation waves,Mach reflection of detonation waves was investigated in a thin rectangular channel,and the schlieren system and smoked foils were used respectively to obtain experimental results about Mach reflection that happened in three kinds of pre-mixtures.The results illustrate that for stable or unstable mixtures,the triple point trajectory rendered by Mach reflection is a curve,which means that the Mach reflection of detonations waves along the wedge doesn＇t have the characteristic of self-similarity as that of the non-reactive shocks.A crucial feature about the non-self-similarity is found that the trajectory of Mach reflection in detonation waves roughly follows triple point trajectory of non-reactive shock theory at beginning of wedge,and then falls on a line parallel to triple point trajectory of reactive shock theory.When the initial pressure was 10 kPa and the wedge angle was 30°,the height of Mach triple point of the pre-mixtures for the transition was 0.8,1.05 cm and 0.5cm respectively,which demonstrates that the transition of unstable mixture happens early than stable mixture.