使用叠栅层析技术解决超音速风洞中复杂密度场的测量难题。应用高灵敏度叠栅偏折仪和间隔角度旋转模型的方法获取超音速风洞中流场的多方向叠栅条纹图。层析计算中使用一种新的偏折角修正迭代的叠栅层析算法,该方法可以实现对有限角采样和包含遮挡物的非完全数据重建,迭代过程中结合内边界平滑滤波提高重建精度。实验中获取了马赫数为2.52的超音速风洞中9幅不同采样角的条纹图,经过50次迭代计算后重建出膨胀波区非对称密度场的截面分布,并对测量结果和误差进行了分析和讨论。使用计算流体力学技术对该密度场进行建模和计算,验证了叠栅层析重建结果的正确性,证实了该技术在测量复杂流场领域的重要价值。

Moiré tomography is applied to measure the complex density distribution in supersonic wind tunnel. Multidirectional moiré fringe patterns of flow field in supersonic wind tunnel are obtained by using high precision moiré deflectometer and discrete angle rotating mode. In the tomography, a new moiré tomographic algorithm with deflection angle revision iteration is employed to realize the limited angle sampling and incomplete data reconstruction containing covering. In the iterative process higher reconstructing precision is achieved by using inner boundary smoothing filtering. In experiments, 9 tomograms with different view angles in supersonic wind tunnel with Mach number 2.52 are obtained, the distribution on the cross section of asymmetric flow field in the swelling area of supersonic wind tunnel is reconstructed after 50 iterative computations, and the measured results and errors are analyzed and discussed. Computing fluid dynamics is used to simulate and compute the density field, verifies the validity of the reconstruction results of moiré tomography, and proves the important value of the technology in measuring complex fluid field.