An Experimental Investigation of Leading Edge Vortices and Passage to Stall of Nonslender Delta Wings
Abstract
This paper describes an experimental investigation of the structure and decay of the leading edge vortices (LEVs) produced by a nonslender delta wing. The work was conducted in a water tunnel facility at the California Institute of Technology and was sponsored by the Air Force Research Laboratory (AFRL). Stereoscopic digital particle image velocimetry was used to obtain three-component velocity data in planar slices across the flow field above the wing leeward surface. These measurements were motivated by flow visualization through dye injection. Delta wings of 50 degree and 65 degree leading edge sweep at Reynolds numbers of 8,000 and 14,000, respectively, were studied. For both wings, stable primary LEVs were observed over the entire planform for 5 degree angle of attack and below. For the 50 degree wing, the secondary LEVs were found to decay more abruptly and at a lower angle of attack than the primary LEVs, all but disappearing by 10 degree angle of attack. This suggests a possible predictive criterion for breakdown of the primary vortices, at least at low Reynolds numbers. The entire vortex system undergoes large-scale instabilities in the 12 degree to 20 degree angle of attack range. The leading edge shear layer, however, remains in an organized rolled-up state in this angle of attack range. By 20 degrees, the flow over the leeward side of the wing is completely stalled. (14 figures, 14 refs.)
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 2003
- Accession Number
- ADA419067
Entities
People
- Michael Ol
Organizations
- Air Force Research Laboratory