径向入射激波聚焦实验和数值模拟研究

Experimental and Computational Studies of Radial Incident Shock Wave Focusing

关键词:  激波  聚焦  径向入射  凹腔  数值研究

Key words:  Shock wave  Focusing  Radial incident  Cavity  Numerical simulation

摘要:

为得到不同入射激波马赫数对凹腔内径向入射激波聚焦过程的影响，对马赫数为1.25和2.18的径向入射激波在实验段内反射聚焦的过程进行了实验和数值模拟研究。用高速CCD拍摄了凹腔中气流流场的纹影图片，并采用保持强稳定性的龙格—库塔格式、加权基本无振荡算法和块结构动态自适应网格加密对激波反射聚焦的过程进行了数值模拟，实验和数值模拟结果吻合较好。复杂的激波形状及其之间的相互作用(如激波反射，激波聚焦和不同激波的相互作用)在实验和数值模拟中都能很好地观测到。通过比较不同马赫数入射激波的反射聚焦过程，发现较高的马赫数下聚焦后能产生射流，而较低的马赫数下却没有。同时发现，入射激波马赫数能影响二次激波出现的位置和强度，进而影响聚焦过程流场的紊乱程度。

Abstract:

In order to obtain the effects of incident shock Mach number on the process of shock wave focusing in a cavity，experiments and numerical simulation were carried out to investigate radial incident shock focusing on a test section where the planar incident shock Mach number was 1.25 and 2.18. CCD camera was used to obtain the schlieren photos of the flow field. Strong-stability-preserving Runge-Kutta method，weighed essential non-oscillation scheme and Block Structured Dynamically Adaptive Mesh Refinement algorithm were adopted to simulate the process of shock wave focusing. There was a good qualitative agreement between the experimental and numerical results. Complex shock wave configurations and interactions such as shock reflection，shock focusing and different shock interaction were observed in both the experiments and numerical calculation results. The shock wave focusing process of different incident shock Mach number were compared. The focusing high Mach number formed a jet while low Mach number did not. Meanwhile，the Mach number of the incident shock wave could determine where the Mach disc formed and its strength，and then influence on flow field stability of shock wave focusing process.