Reynolds number and leading-edge bluntness effects on a 65-deg delta wing

Abstract

A 65°delta wing has been tested in the National Transonic Facility (NTF) at mean aerodynamic chord Reynolds numbers from 6 million to 120 million at subsonic and transonic speeds. The configuration incorporated systematic variation of the leading edge bluntness. The analysis for this paper is focused on the Reynolds number and bluntness effects at subsonic speeds (M = 0.4) from this data set. The results show significant effects of both these parameters on the onset and progression of leading-edge vortex separation.

Off-Design Reynolds Number Effects for a Supersonic Transport

“…As the leading-edge radius becomes smaller, the flow will separate at lower angles of attack. 25,26 The vortex lift increment associated with the increased extent of inboard wing leading-edge separation is consistent with an increased drag level shift as well as a more nose-up pitching moment (vortex lift increase ahead of moment reference center) observed for the high Reynolds number grouping. Keep in mind that even though frost contamination on the wing leading edge was not observed during any of the testing, it was not due to any negligence in the testing procedures.…”

“…25,26 Note that the inboard leading-edge radius for the supersonic transport model would compare to the medium to large leading-edge bluntness configurations discussed in the 65° delta wing study.…”

What was learned from the new VFE-2 experiments

“…2. The results of these measurements have been analyzed and summarized in various papers [2][3][4][5] . In the 2001 proposal 6 for a new vortex-flow research program, the NASA 65° delta wing configuration with sharp and rounded leading edges was chosen for new tests concerning additional drag and flow field data.…”

Numerical prediction and wind tunnel experiment for a pitching unmanned combat air vehicle

“…After breakdown, the vortex wake quickly moves up and behind the leading-edge, leading to higher pressures on the upper surface of the wing. The vortices are very wide compared with their height, most likely due to the rounded leading edges of the wing, and the possible formation of a double primary vortex system [8,21]. Secondary vortices are also visible beneath the primary vortices.…”