斜激波串与上游激波干扰特性试验研究

为研究斜激波串在背压条件下前移与上游激波相互干扰的流场结构和运动规律，在来流为马赫数 2.7 的直管道内设计一种等宽度斜楔，采用动态压力测量、高速纹影和粒子图像测速(PIV)技术等手段进行了试验。研究结果表明：内置斜楔在管道内产生入射激波、分离激波、膨胀波、再附激波和激波诱导分离等复杂上游激波流场，在分离区附近形成有顺压梯度和逆压梯度的区域。当增大下游压比时，斜激波串逐渐向上游激波流场移动；经过斜楔产生的分离区时，斜激波串的移动速度急剧提升，同时出现非对称分离偏转方向的切换。对比了三种长度尺寸的等楔角斜楔所产生的上游激波流场的差异性，发现在相同的斜楔前缘起始点和楔角时，随着斜楔长度的增加，上游激波流场中激波诱导的分离尺度逐渐变大。

Experimental Study of Oblique Shock Train and Upstream Shocks Interaction

To study the interaction of the oblique shock trains and upstream shocks, three ramps with equal widths are installed inside a Ma 2.7 straight duct, and the experiments are conducted with high frequency pressure measurements, high-speed Schlieren visualizations and particle image velocimetry (PIV) testing. The results show that the ramps generate a complex background flow field inside the duct, which includes an incident shock, separated shock, expansion wave, trailing edge separation, shock induced separation, and flow areas with favorable and adverse pressure gradients. The oblique shock train gradually moves towards the upstream with a linear increase in the downstream pressure ratio. The rate of the movement of the oblique shock train increases rapidly when it passes through the separation regions generated by the ramp, and the deflection direction of the asymmetric separation switches. As the length of the ramp increases with the same location and the ramp angle, the size of the shock-induced separation in the background flow field gradually increases.