超声速气膜气动光学效应与Reynolds数相互关系实验研究

目前，随着相关项目研究的不断推进，如何在高Reynolds数下研究其对气动光学效应的影响成为重要命题.通过设计变Reynolds数气动光学效应实验平台，模拟的单位Reynolds数可以在7.2×106~2.2×108 m-1范围内变化.搭建的基于背景纹影（background oriented schlieren，BOS）的波前测试系统可以达到6 ns的时间分辨率.此系统测量的平凸透镜波前结果表明:实验测量结果与理论计算结果的误差在±4%以内.通过测量9种不同Reynolds数下的超声速气膜瞬态波前数据，分析结果表明:在高Reynolds数条件下，Reynolds数对于超声速气膜气动光学效应的影响比较明显，通过对实验数据进行函数拟合发现OPD_rms∝Re0.88，与推导结果OPD_rms∝Re0.9十分接近；利用小波分析方法研究了高Reynolds数条件下气动光学效应沿流向的分布特征，发现OPD_rms的低频部分（信号的主体）先降低后升高，但是高频部分的震荡幅度先升后降.分析认为OPD_rms的低频部分主要受到流场整体结构的影响，而高频部分更多地受到涡的空间分布影响. 

Experimental Investigation on Relationship between Reynolds Number and Aero-Optics Produced by Supersonic Films

Nowadays, with development of relevant projects, it is becoming an important proposition how to study high Reynolds effects on the aero-optical distortions. Experiment unit Reynolds number can change from 7.2×106~2.2×108 m-1 by designing a variable Reynolds number aero-optical experiment equipment. A wavefront measurement system based on BOS was assembled, and its temporal resolution can reach to 6 ns. With this system, the measurement results from the plano-convex lens wavefront show that:experimental measurement error compared to the theoretical calculation is within ±4%. The transient wavefronts of supersonic film in nine different Reynolds conditions were measured. The analysis shows that, in high Reynolds condition, Reynolds has obvious effects on the supersonic film aero-optical distortion. OPD_rms∝Re0.88 was found by function fitting the experimental data, which is similar with the derivation result OPD_rms∝Re0.9. The distribution features of aero-optical distortion along flow direction were studied by wavelet analysis methods in high Reynolds condition. Low-frequency portion (body signals) of OPD_rms decreased firstly then increased, but the volatility of its high frequency portion increased firstly and then decreased. The low-frequency part of OPD_rms is primarily affected by the overall structure of the flow field, and the high-frequency part is affected by the spatial distribution of the vortex.