Water Tunnel Investigation of the Vortex Dynamics of Periodically Pitched Wings
Abstract
The vortex structure above semi-span wings was investigated in the AFFDL's 24-inch water tunnel to determine the effects of periodic pitching using a saw-tooth motion. Each of the six wings was pitched about the mid-chord at nondimensional upstroke rates ranging from 0.05 to 0.30 and down-stroke rates from 0.025 to 0.600 at tunnel flow rates of 0.6 to 3.6 in/sec. Visualization of the vortices obtained through dye injection from the models was recorded using both high speed and 3/4-in. standard speed video systems. Digitized data from the high speed system provided trend data which showed the saw-tooth motion caused a hysteresis effect on the vortex breakdown location for the swept wings where during the upstroke the vortex would burst further aft than during the down-stroke. In addition, comparison of two 65-deg sweep wings with different cross sections (flat plate and NACA 0012-34) showed a smaller hysteresis effect for the thicker wing. For the rectangular wing, increasing down-stroke rates resulted in higher dynamic stall vortex convection rates. Information was also gathered on the oscillation of static breakdown location and the effects on vortex breakdown of tunnel flow velocity. Keywords: Water tunnels, Dynamic stall, Pitching wing, Vortex breakdown. Theses.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1988
- Accession Number
- ADA206359
Entities
People
- Michael David
Organizations
- Air Force Institute of Technology