Fiber-optic-based device for the investigation of aero-optic effects

Lori C. Brooks; David A. Kalin; Bruce R. Peters

doi:10.1117/12.137847

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21 September 1992 Fiber-optic-based device for the investigation of aero-optic effects

Lori C. Brooks; David A. Kalin; Bruce R. Peters

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Proceedings Volume 1687, Characterization, Propagation, and Simulation of Sources and Backgrounds II; (1992) https://doi.org/10.1117/12.137847
Event: Aerospace Sensing, 1992, Orlando, FL, United States

Abstract

Mixing/shear layer turbulence is the major contributor to optical degradation effects experienced by a windowed hypersonic vehicle. A critical component in the prediction of these aero-optic effects, is the distribution, relative sizes, and velocities of the turbulent structures found within the mixing/shear layer. Previous attempts have had difficulty in measuring these high frequency, small scale turbulent properties. Therefore, a novel non-intrusive optical technique called the fiber optic flow monitor, was developed. This device was used in conjunction with a dual nozzle aero-optic simulator to experimentally determine turbulent flow properties and investigate their relationship to image distortion. The flow field studied was a dual species mixing/shear layer that had a mean flow velocity of approximately 430 m/s with a calculated mean turbule size of 0.7 mm. It was observed that the turbulent structures redistributed incident collimated energy into unique patterns of light. By monitoring these patterns, it was possible to measure several flow field properties. Data, gathered from this technique, was used to compute a statistical distribution of turbule velocities that was compared to theoretical predictions and image distortion parameters. Close correlation between experimental and theoretical values confirms that the technique provides a non- intrusive method of accurately characterizing small scale, high velocity turbulent structures.

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Lori C. Brooks, David A. Kalin, and Bruce R. Peters "Fiber-optic-based device for the investigation of aero-optic effects", Proc. SPIE 1687, Characterization, Propagation, and Simulation of Sources and Backgrounds II, (21 September 1992); https://doi.org/10.1117/12.137847

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