Mr. Cheng Chen Profile

Cheng Chen

at Beijing Electronic System Engineering Institute

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Publications (1)

Proceedings Article | 27 August 2011 Paper

Study on the temporal and spatial characteristics of high-speed turbulent flow field and its optical transmission effects

Cheng Chen, Jindong Fei, Shihe Yi, Wenzhuo Tang

Proceedings Volume 8193, 819303 (2011) https://doi.org/10.1117/12.900013

KEYWORDS: Nanolithography, Geometrical optics, Atmospheric propagation, Transmittance, Imaging systems, 3D image processing, Wave propagation, 3D modeling, 3D image reconstruction, Sensors

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When the aircraft flights in the earth's atmosphere with high speed, it will bring the aero-optical effects into optical imaging detector system. These aero-optical propagation effects are caused by two parts: high-speed turbulent flow field and aero-thermal window. This paper discusses the light propagation effects caused by high-speed turbulent flow field. The high-speed turbulent flow field is a highly non-uniformly time-varying medium, which possesses some characteristics depending on both time and space. While the light propagates through such a medium, the imaging on target of detector system will be affected. This paper describes both the temporal and spatial characteristics of high-speed turbulent flow field. To obtain the instantaneous distribution characteristics of turbulent flow field, one method is applying NPLS-based measurement technique of supersonic flow field. The three-dimensional density field is obtained by the relationship between density and image gray. We studied the physical phenomena of optical wave propagating through turbulent flow field and then the caused optical distortion. The NPLS technique is a high-resolution measurement method of the fine structure of supersonic three-dimensional complex flow field. The time resolution of NPLS technique is 6 ns, and the time correlation resolution is 200 ns. These resolutions can satisfy the description of the characteristics related to the time scale. We are able to describe the time correlation characteristics of density field using NPLS image with different time intervals. Finally, the optical transmission effects of light, which propagates through turbulent flow field, were simulated and studied. According to the instantaneous density field obtained from the NPLS technique, it is carried out that the simulation of optical transmission effect of high-speed turbulent flow field at several typical states. Then, using the ray-tracing method, the optical distance OPDi along the propagation path is obtained.

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