大尺度结构对气动光学效应影响的实验研究

Effect of Large-scale Structures on Aero-optic Effect

为了深入研究细光束穿越可压缩混合层后光束畸变的机理,本文提出将双曝光CCD相机成像技术与纹影技术相结合进行流场与光束畸变的同步测量。利用纹影技术获得可压缩混合层密度梯度场特征,进而获得大尺度结构的密度梯度场分布;利用CCD相机成像技术获取通过混合层后光束畸变特性;双曝光技术的引入可以得到大尺度结构的移动对细光束畸变的影响。实验研究结果表明:流场中大尺度结构的存在导致了光束的偏移和模糊,而这些大尺度结构的移动的确可以使经过它们的光束随之移动。

To carefully investigate the mechanism of thin light beam aberration passing through compressible mixing layer,double-exposure CCD camera imaging system and schliren system have been used to synchronously measure the flow field and aero-optical aberration.The distribution of density gradation can be obtained by use of schliren system.In addition,owing to adopting CCD camera imaging system,the aberration images of thin light beam can also be acquired.Moreover,adopting double-exposure technique can present the information of motion and shape of a large-scale structure,and then show its effect on optical aberration.A conclusion from the experimental results can be drawn that the existence of large-scale structure in flow field leads to the tilt and blur of light beam and the motion of large-scale structure results to the corresponding motion of light beam.