高超声速进气道-隔离段反压引起不起动计算

Calculation of unstarted flow in hypersonic inlet-isolator with high back pressure

对某典型二元高超声速进气道流场进行了数值分析,将不同反压条件下沿程壁面压力分布和实验数据进行了比较,结果表明计算成功、可信,所用计算软件可用于高超声速进气道流动计算。针对反压增加引起的进气道不起动现象,提出了反压引起进气道不起动流动的数值计算方法,解决了直接给定出口反压不能模拟进气道不起动的问题,计算所得进气道不起动时沿程壁面压力分布与实验结果吻合较好。研究发现,在不同反压下隔离段中的平均马赫数和平均压力值,从隔离段进口到激波串波前基本保持不变。当反压过高造成进气道不起动时,进气道进口前形成一道斜激波而不是正激波,波后有很大的分离,形成超声溢流,此时反压降到最大承受反压的一半左右。

The 3-D flow of a typical 2-D scramjet inlet was numerically simulated and the computational static pressure distributions on the wall at different back pressure were compared with the experimental data. The comparison showed that the numerical results agreed well with the measurements. In order to study the inlet unstart phenomena caused by back pressure rise, a method for simulating inlet unstart was present and the numerical results agreed well with the experimental data. It was observed that the average values of Mach numbers and pressures were almost constant from the entrance of the isolator to the onset of shock train along the isolator. When inlet unstarted, there was an oblique shock instead of a normal shock standing in front of the entrance. A large separation region was formed behind the shock and supersonic spillage occurred. The value of back pressure was about half of the peak back pressure.