超声速湍流边界层气动光学效应的实验研究

当光线穿过超声速湍流边界层时受到湍流密度脉动的影响，其传播方向和相位会发生变化，使得目标图像出现模糊、偏移和抖动等现象，给目标识别带来困难。利用基于背景导向纹影（Background Oriented Schlieren，BOS）原理开发的基于BOS的波前传感（BOS-based Wavefront Sensor，BOS-WS）技术获得了光波通过马赫数Ma=3.0的超声速湍流边界层后的波前。基于波动光学原理计算出相应的点扩散函数（Point Spread Function，PSF）分布以及退化图像，研究结果表明:测量得到的波前结果对应的PSF与理想平面波前对应的PSF相比，在峰值的大小、所在位置及形态上变化较大，PSF峰值出现衰减，PSF峰值位置出现较为明显的偏移，PSF形态出现多峰现象，湍流边界层内密度分布较强的空间随机性得到体现，经此PSF处理后的图像出现一定程度的退化。

Experimental investigation of aero-optical effect due to supersonic turbulent boundary layer

When a planar optical wavefront is made to propagate through a supersonic turbulent boundary, affected by the density fluctuation, its propagation direction and phase will change, which make target image blur, shifting, jitter et al and bring problems for target identification. By using the BOS-based Wavefront Sensing(BOS-WS) technique based on the principle of Background Oriented Schlieren(BOS), the optical wavefront propagated through a Ma=3.0 supersonic turbulent boundary layer was acquired. Based on the wave optics principles, the corresponding Point Spread Function(PSF) distribution and degraded image were computed. The research results show that many changes are found on the PSF peak value, peak value location and shape. The PSF peak value deceases largely, the PSF value peak position appears a significant move, the PSF shape appears multi peaks phenomenon, the spatial randomness of turbulent boundary layer density distribution is obtained, the image appears to a certain degree degradation after the PSF processing.