Analysing the structure of the optical path length of a supersonic mixing layer by using wavelet methods

作者：Gao Qiong^*; Yi Shi He; Jiang Zong Fu; Zhao Yu Xin; Xie Wen Ke

来源：Chinese Physics B, 2012, 21(6): 064701.

DOI：10.1088/1674-1056/21/6/064701

• optical path difference
• aero-optics
• supersonic mixing layer
• wavelet
• coherent structures
• scaling behavior

The nano-particle-based planar laser scattering (NPLS) technique is used to measure the density distribution in the supersonic mixing layer of the convective Mach number 0.12, and the optical path difference (OPL), which is quite crucial for the study of aero-optics, is obtained by post processing. Based on the high spatiotemporal resolutions of the NPLS, the structure of the OPL is analysed using wavelet methods. The coherent structures of the OPL are extracted using three methods, including the methods of thresholding the coefficients of the orthogonal wavelet transform and the wavelet packet transform, and preserving a number of wavelet packet coefficients with the largest amplitudes determined by the entropy dimension. Their performances are compared, and the method using the wavelet packet is the best. Based on the viewpoint of multifractals, we study the OPL by the wavelet transform maxima method (WTMM), and the result indicates that its scaling behaviour is evident.

• 出版日期2012-6
• 单位中国人民解放军国防科学技术大学