Unsteady density and velocity measurements in the 6 foot x 6 foot wind tunnel
Abstract
The methods used and the results obtained in four aero-optic tests are summarized. It is concluded that the rather large values of density fluctuation appear to be the result of much higher Mach number than freestream and the violent turbulence in the flow as it separates from the turret. A representative comparison of fairing on-fairing off rms density fluctuation indicates essentially no effect at M = 0.62 and a small effect at M = 0.95. These data indicate that some slight improvement in optical quality can be expected with the addition of a fairing, although at M = 0.62 its effect would be nil. Fairings are very useful in controlling pressure loads on turrets, but will not have first order effects on optical quality. Scale sizes increase dramatically with increasing azimuth angle for a reprensentative condition. Since both scale sizes and fluctuation levels increase (total turbulence path length also increases) with azimuth angle, substantial optical degradation might be expected. For shorter wave lengths, large degradations occur.
- Publication:
-
In its Proc. of the Aero-Optics Symp. on Electromagnetic Wave Propagation from Aircraft p 153-181 (SEE N80-25588 16-34
- Pub Date:
- April 1980
- Bibcode:
- 1980ewpa.proc..153R
- Keywords:
-
- Boundary Layer Flow;
- Flow Velocity;
- Radiant Flux Density;
- Wind Tunnel Tests;
- Optical Properties;
- Refractivity;
- Turbulence;
- Velocity Measurement;
- Wave Degradation;
- Fluid Mechanics and Heat Transfer