孔板扰动对爆轰波胞格结构特性影响的实验研究

Experimental research on the influence of orifice plate perturbation on detonation cellular structure characteristics

实验采用稳定预混气2H2+O2+3Ar及不稳定预混气C2H2+5N2O和CH4+2O2,在圆形爆轰管内通过烟膜手段记录了爆轰波的胞格结构,得到了胞格尺寸与初始压力之间的关系式;研究了胞格结构在扰动上下游的变化过程,分析了胞格不稳定性对胞格结构特征的影响,获得了爆轰波经过扰动后重新恢复至平衡状态的特征尺度。结果表明:爆轰波经过扰动后,对于稳定预混气,在扰动下游主胞格结构变得不规则,没有出现次生胞格;对于不稳定预混气,扰动下游伊始爆轰波的次生模态被抑制,由于爆轰波自身的不稳定性,随后出现了局部爆炸点及精细胞格结构;爆轰波在扰动下游传播了一段距离后恢复至平衡状态,该长度在8~15倍之间的胞格尺寸范围内变化,并且随初始压力的变化趋势并不明显。研究结果反映出爆轰波经过孔板扰动后恢复至平衡态所需的长度与爆轰波流体动力学厚度相当。

The influence of orifice plate perturbation on detonation cellular structure was experimentally investigated.The cellular structure of detonation wave was recorded in a circular detonation tube withthe smoked film method.The stable mixture 2H2+O2+3Ar and unstable mixture C2H2+5N2O and CH4+2O2 were used.The correlation between cell size and initial pressure was obtained.The variations of cellular structure upstream and downstream of perturbation were studied,and influence of cellular instability oncellular structure characteristics was analyzed.The characteristic length scaleofdetonation recovery from perturbation was obtained.The results show that after the perturbation the main cell structure becomes irregular when no secondary cells appearfor the stable mixture,while for the unstable mixture,the secondary modes of the detonation wave downstream of the perturbationareinitially suppressed,subsequently the local explosions and fine cellsare generated due to the cellular instability.The detonation wave propagates some distance and recovers to the equilibrium state.This characteristic length varies within the range of 8 to 15 timesthe cell size,while it does not change with the initial pressure.The resultimplies that the characteristic length scale of the detonation wave recovery fromthe perturbationequatesto the detonation hydrodynamic thickness.