基于相位展开和一种新的迭代重建算法的流场莫尔层析术

Flow Field Moire Tomography Based on Phase Unwrapping and a New Iterative Reconstruction Algorithm

使用莫尔层析方法测量温度场。设计了一种旋转莫尔偏折仪,该装置可以获取180°范围内的莫尔条纹图。采用傅里叶变换相位展开技术处理莫尔条纹,提取轴向任意截面的投影信息,使用一种新的莫尔层析迭代算法重建温度分布,该迭代算法与已有的代数重建算法不同,它由莫尔偏折基本公式和网格重建技术推导得出,直接使用光线偏折角进行迭代,可以直接实现对非完全投影数据的层析重建。实验中使用8个方向的莫尔条纹图对双峰结构温度场进行重建,得到了截面的温度分布,峰值的重建误差低于5%。测量结果证明这是一种准确、适用性广的层析重建方法。

Moire tomography is applied in fully quantitative measurement of temperature distribution. Rotary moire deflectometer is designed to capture multidirectional optical projections, and moire patterns of temperature field can be obtained in 180 degrees. The information of fringe pattern is abstracted by phase unwrapping using Fourier transform. The temperature distribution of asymmetric flow field is calculated from incomplete projection data by a new iterative reconstruction algorithm, which is derived from basic moire deflection formula and discrete element reconstruction technique. The deflection angle is applied directly in iteration, which is completely different from the previous transform methods and existing series expansion methods. In experiment, the asymmetric temperature distribution was reconstructed by 8 projections with different view angles, and some measurement errors were discussed. The results prove that it is an accurate and practical tomography technique.