高超声速圆锥边界层不稳定性及转捩实验研究

在马赫数为6的条件下，利用红外热成像和高频脉动压力传感器（PCB）对前缘半径2 mm、半锥角7°的圆锥模型进行了边界层稳定性及转捩实验研究。实验结果表明，在常规高超声速风洞流场中圆锥三维边界层存在定常横流涡、低频和高频不稳定波；有迎角条件下，低频（15～50 kHz）和高频（210～340 kHz）不稳定波同时存在，圆锥边界层更容易发生转捩。随着迎角的增加，定常横流涡“条带”结构更加清晰，模型尾段的转捩阵面向迎风面移动，低频和高频不稳定波振幅增大、频带范围变宽；同一迎角下，增大单位雷诺数，低频、高频不稳定波和定常横流涡更早地出现并增长至饱和，且伴随着不稳定波的振幅增大和频带变宽，其中低频不稳定波比高频不稳定波更早出现。

Experimental study on instability and transition over hypersonic boundary layer on a straight cone

The instability and transition of a cone model with a nose radius of 2 mm and a half cone angle of 7° were studied using infrared thermography and a high-frequency pressure sensor （PCB） at Ma = 6. The experimental results show the presence of a stationary crossflow streaks, low and high frequency unstable waves in the three-dimensional boundary layer of the straight cone in the flow field of a conventional hypersonic wind tunnel. Under nonzero angle of attack, low-frequency （15?50 kHz） and high-frequency （210?340 kHz） unstable waves exist at the same time, and the boundary layer transition is more likely to occur. With the increase of the angle of attack, the streaks become clearer, the transition front of the model moves toward the windward side, and the amplitude of low-frequency and high-frequency unstable waves increases and the band ranges enlarge. The amplitude of the unstable waves increases and the frequency band widens, and the low-frequency unstable waves appear earlier than the high-frequency unstable waves. At the same angle of attack, with the increase of unit Reynolds number, high-frequency and low-frequency unstable waves and stationary crossflow streaks appear earlier and grow to saturation, accompanied by the increase of the amplitude and bandwidth of the unstable waves. In addition, the low frequency unstable waves appear earlier than the high-frequency unstable waves.