Experimental demonstration of bow-shock instability and its numerical analysis
Experimental demonstration of bow-shock instability and its numerical analysis
复制标题
弓激波失稳实验演示及其数值分析
DOI：
10.1007/s00193-016-0669-5
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发表时间：
2017
期刊：
影响因子：
2.2
通讯作者：
K. Ohtani
中科院分区：
文献类型：
--
作者：
Y. Kikuchi;N. Ohnishi;K. Ohtani
在高马赫数弹道范围内，用低比热比气体氢氟烃HFC-134a对超音速钝体前方产生的不稳定弓激波进行了实验演示。实验得到的阴影图像显示出不稳定的特征，其中扰动增长并向下游流动，尾流因激波振荡而呈现波浪状。此外，在不同的实验条件下，考察了体型和比热比对不稳定性的影响。此外，数值模拟还捕捉到了观测到的波动结构和扰动幅度等特征，证明了计算流体力学能够有效地模拟物理不稳定性。此外，还推断了冲击不稳定性是由物体边缘的声发射引起的。这一推论支持了不稳定性与比热比和马赫数的关系，因为激波距离受这些参数的影响，并限制了声波的传播。
An experimental demonstration was carried out in a ballistic range at high Mach numbers with the low specific heat ratio gas hydrofluorocarbon HFC-134a to observe the unstable bow-shock wave generated in front of supersonic blunt objects. The shadowgraph images obtained from the experiments showed instability characteristics, in which the disturbances grow and flow downstream and the wake flow appears wavy because of the shock oscillation. Moreover, the influence of the body shape and specific heat ratio on the instability was investigated for various experimental conditions. Furthermore, the observed features, such as wave structure and disturbance amplitude, were captured by numerical simulations, and it was demonstrated that computational fluid dynamics could effectively simulate the physical instability. In addition, it was deduced that the shock instability is induced by sound emissions from the edge of the object. This inference supports the dependence of the instability on the specific heat ratio and Mach number because the shock stand-off distance is affected by these parameters and limits the sound wave propagation.