AIAA Paper 95-1795, Applied Aerodynamics Conference, San Diego, CA, June 1995.

 

MODIFICATION OF SPECTRAL CHARACTERISTICS  IN A

VORTEX FLOW FIELD

James Paul Hubner and Narayanan M. Komerath
Georgia Institute of Technology
Atlanta, GA  30332-0150

 ABSTRACT

 The origin of nearly-periodic velocity fluctuations over a delta wing was investigated, and the results were used to modify these fluctuations.  Smoke streakline videography, surface hot-films and phase-resolved laser velocimetry were used to quantify fluctuations and visualize structures near the surface of the 59.3°-delta wing.  The evolution of the measured fluctuations over a cycle of periodicity showed the convection of rotating structures.  Small  fences attached to the leeward side of the model modified the fluctuations.  Fence-off and -on lift, drag and pitching moment measurements verified wing performance while autospectral measurements quantified modification of the fluctuations.  A fence aligned parallel and inboard of the secondary vortex separation line displayed the most overall attenuation with the least effects on aerodynamic characteristics.  Other fence alignments showed varying results including frequency shifts and spectral amplification.  These modifications further demonstrate the origination and importance of fluctuations near the surface, as opposed to the core of the vortex or the wing leading-edge.