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

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....

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Bibliographic Details
Published in:Chinese physics B 2012-06, Vol.21 (6), p.344-351
Main Author: 高穹 易仕和 姜宗福 赵玉新 谢文科
Format: Article
Language:English
Subjects:
Coherence
Entropy
Lasers
Nanostructure
Optical paths
Supersonic aircraft
Transforms
Wavelet
Wavelet transforms
光路
密度分布
小波包
时空分辨率
正交小波变换
结构分析
超音速混合层
长度
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Summary: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 ana]ysed 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.
ISSN:1674-1056
2058-3834
1741-4199
DOI:10.1088/1674-1056/21/6/064701