对于高超声速飞行试验，飞行器在飞行过程中产生的气动加热会使其表面安装的传感器烧坏并导致试验测量失败。传感器下沉安装可以避免其与飞行器周围的高温气体直接接触，减轻传感器的热载荷。采用下沉安装传感器的方式对高超声速边界层的脉动压力进行了试验测量，研究了测压孔径对脉动压力特性的影响。结果表明，随着孔径增大，脉动压力强度减小，流场相关性增强。传感器下沉安装会引起空腔流动，随着孔径的增大，空腔流动对脉动压力测量的影响降低。在频带10~20 kHz范围内，测压孔径仅仅影响脉动压力强度，在频带1~10 kHz范围内，测压孔径对脉动压力波形周期的影响更为显著。非线性耦合将能量由高频小尺度向低频大尺度传递，导致发生自相互作用和非线性相位耦合的流动结构趋向低频，随着孔径增大，非线性相位耦合消失。此外，孔径越大，不同尺度结构的能量分布与齐平安装的相似性越高。
Aerodynamic heating produced in the hypersonic flight test will destroy the pressure transducers mounted on the vehicle surface and lead to measurement failure. Recessed installation of transducers can avoid direct contact with the high temperature air surrounding the vehicles and abate the excessive heat loads. In this paper, experimental measurements of pressure fluctuations in a hypersonic boundary layer are carried out based on recessed installation of transducers and the effects of opening diameter on characteristics of fluctuating pressure are studied. The results show that the intensity of pressure fluctuation is reduced and the correlation of flow field is enhanced as the opening diameter increases. Recess mounting could cause cavity flow, and the influence of cavity flow on fluctuation pressure measurement is reduced as the opening diameter increases. Within the frequency band of 10-20 kHz, the opening diameter only mildly influences the fluctuating pressure intensity, but within the frequency band of 1-10 kHz, the opening diameter exerts more significant effects on the wave period of pressure fluctuations. Nonlinear phase lock resonance transfers the energy from high frequency structures to low frequency structures, leading to the flow structures occurring self-interaction and nonlinear phase coupling tending to the low frequency. As the opening diameter increases, the nonlinear phase coupling finally vanishes. In addition, the energy distributions of different scale structures share higher similarity with those under flush mounting with the increasing opening diameter.
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