Accession Number : ADA113910

Title :   Nearfield Aerodynamics and Optical Propagation Characteristics of a Large-Scale Turret Model.

Descriptive Note : Final rept.,


Personal Author(s) : Rose,William C ; Craig,James E ; Raman,K R

PDF Url : ADA113910

Report Date : Feb 1982

Pagination or Media Count : 100

Abstract : Measurements of the unsteady flow field affecting optical propagation quality have been made with both aerodynamic and direct optical instrumentation. Properties affecting degradation of coherent radiation beams propagated from within the turret have been investigated. These properties include both the magnitude and scale sizes of the fluctuating index-of-refraction field present in the turbulent shear layers and separation regions of the turret flow field. Direct optical degradation information was obtained by holographic interferometry and quantified through techniques presented here. Aerodynamic measurements were made with hot-wire anemometry and multiple-port probes. Comparisons between the aerodynamically and optically deduced data are presented. These data can be used directly to estimate trends in expected loss of optical quality of a coherent beam for various flight speeds, altitudes, wavelengths and azimuthal turret angles. More data are now available for estimating the effects of unsteady aerodynamic flow fields on optical propagation quality. Data were obtained for Reynolds numbers near those occurring at full-scale flight conditions over a range of Mach number from 0.55 to 0.75. Investigation results generally agree with those obtained previously on smaller scale models and indicate that severe optical degradation can be present at aft-looking azimuth angles. (Author)

Descriptors :   *Laser beams, *Degradation, *Turbulence, *Aircraft turrets, Atmospheric refraction, Shear properties, Nonuniform flow, Air flow, Flow separation, Flow fields, Aerodynamics, Refractive index, Optical detection, Anemometers, Holography, Optical interferometers, Wind tunnel tests, Distortion, Wavefronts, Light transmission

Subject Categories : Lasers and Masers

Distribution Statement : APPROVED FOR PUBLIC RELEASE