雷诺数对超声速气膜气动光学效应影响的实验研究

Experimental investigation of influence of Reynolds number on supersonic film aero-optics

受到风洞实验能力的限制,高速飞行器气动光学效应实验很难与其实际飞行情况完全一致。雷诺数作为重要的相似准则数,在经典流体力学风洞实验中应用广泛,研究其对于气动光学效应的影响,对于建立气动光学相似准则具有重要意义。基于∏定理对可能影响气动光学效应的变量进行分析,证明了雷诺数是影响气动光学效应的一个相似准则数;通过创新性设计变雷诺数实验装置,可以实现喷流单位雷诺数在106~108 m-1范围内变化。通过选取八个典型的雷诺数,并利用BOS-WS(BOSbased Wavefront Sensor)技术测量了对应状态的光程差,通过函数拟合的方法得到了光程差的均方根值与雷诺数之间的幂函数关系式。通过对不同孔径下的测量结果进行对比和归一化处理可以发现,对于二维超声速气膜而言,观察孔径尺寸并不会对获取的规律产生影响。

Due to the limitation of wind tunnel test capability, it was very hard to be completely consistent with the actual flight of high speed aircraft. As an important similarity number, Reynolds number had been used widely in classical fluid mechanics wind tunnel experiments. It had a significant impact on establishing aero-optical similarity standard to study the influence on aero-optics induced by Reynolds number. Based on the I-I theorem, the possible variables that affected aero-optics were analyzed, which verified Reynolds number was a similarity standard value of aero-optics. A creative experimental equipment was designed to realize the unit Reynolds number ranging from 106-108 m-1 Eight typical Reynolds numbers were chosen, BOS-WS （BOS-based Wavefront Sensor） technique was used to measure the corresponding optical path difference. Based on the function curve fitting method, the power function between Reynolds number and the rms of the optical path difference was acquired. The measured results with different sizes were compared. It could be found that, for the two dimensional supersonic film, the acquired law was not affected by the size of the observed aperture.