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Proceedings Paper

Analyzing the structure of the optical path difference of the supersonic film cooling
Author(s): Haolin Ding; Shihe Yi; Jia Fu; Lin He
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Paper Abstract

While high-speed aircraft are flying in the atmosphere, its optical-hood is subjected to severe aerodynamic heating. Supersonic film cooling method can effectively isolate external heating, but the flow structures formed by the supersonic film cooling can cause the beam degradation and affect the imaging quality. To research the aero-optics of supersonic film cooling, an experimental model was adopted in this paper, its mainstream Mach number 3.4, designed jet Mach number 2.5, measured jet Mach number 2.45. High-resolution images of flow were acquired by the nano-based planar laser scattering (NPLS) technique, by reconstructing the density field of supersonic film cooling, and then, the optical path difference (OPD) were acquired by the ray-tracing method. Depending on the comparison between K-H vortex and OPD distribution, the valleys of OPD correspond to the vortex ‘rollers’ and the peaks to the ‘braids’. However, the corresponding relationship becomes quite irregular for the flow field with developed vortices, and cannot be summarized in this manner. And then, the OPD were analyzed by correlation function and structure function, show that, there is a relationship between the shape of OPD correlation function and the vortex structure, the correlation function type changed with the development of the vortex. The correctness that the mixing layer makes a main contribution to the aero-optics of supersonic film cooling was verified, and the structure function of aero-optical distortion has a power relationship that is similar to that of atmospheric optics. At last, the power spectrum corresponding to the typical region of supersonic film cooling were acquired by improved periodgram.

Paper Details

Date Published: 19 October 2016
PDF: 8 pages
Proc. SPIE 10155, Optical Measurement Technology and Instrumentation, 1015516 (19 October 2016); doi: 10.1117/12.2245737
Show Author Affiliations
Haolin Ding, National Univ. of Defense Technology (China)
Shihe Yi, National Univ. of Defense Technology (China)
Jia Fu, National Univ. of Defense Technology (China)
Lin He, National Univ. of Defense Technology (China)

Published in SPIE Proceedings Vol. 10155:
Optical Measurement Technology and Instrumentation
Sen Han; JiuBin Tan, Editor(s)

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