A conceptual study of leading-edge-vortex enhancement by blowing

Bradley, R. G.; Wray, W.O.

doi:10.2514/6.1973-656

Cited by 2 publications

(5 citation statements)

References 2 publications

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“…Blowing parallel to the leading-edge from a location near the apex and in the symmetry plane [34] showed substantial lift enhancement in the post-stall region, in particular for a low sweep angle of Λ = 40°. At an incidence of α = 30°, an effectiveness of ∆C L /C µ around 5 was found for C µ = 0.09.…”

Section: Small Aspect Ratio Jetsmentioning

confidence: 97%

“…Small aspect ratio jets have been used for adding momentum from a location near the apex in the symmetry plane and parallel to the leading-edge [34,35] (see Figure 16), for along-the-core blowing underneath the vortex axis [36,37], for spanwise blowing underneath the vortex axis [38], and outward blowing from the leading-edge [39].…”

Section: Small Aspect Ratio Jetsmentioning

confidence: 99%

“…In fact, for pre-stall incidences when vortex breakdown exists over the wing, the effect of the excitation on the normal force is negligible as shown in Figure 22. Figure 23 compares the effectiveness ∆C N /C µ for the unsteady blowing [51,52] and steady blowing [28,34,35]. It is seen that there is great potential in active flow control based on unsteady excitation in the post-stall lift enhancement.…”

Section: High-frequency Excitationmentioning

confidence: 99%

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Review of flow control mechanisms of leading-edge vortices

Gursul

Wang

Vardaki

2007

Progress in Aerospace Sciences

135

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Vortex control concepts employed for slender and nonslender delta wings were reviewed. Important aspects of flow control include flow separation, vortex formation, flow reattachment, vortex breakdown, and vortex instabilities. The occurrence and relative importance of these phenomena strongly depend on the wing sweep angle. Various flow control methods were discussed: multiple vortices, control surfaces, blowing and suction, low-frequency and high-frequency excitation, feedback control, passive control with wing flexibility, and plasma actuators. For slender delta wings, control of vortex breakdown is achieved by modifications to swirl level and external pressure gradient acting on the vortex core. Effects of flow control methods on these two parameters were discussed, and their effectiveness was compared whenever possible. With the high-frequency excitation of the separated shear layer, reattachment and lift enhancement in the post-stall region is observed, which is orders of magnitude more effective than steady blowing. This effect is more pronounced for nonslender wings. Re-formation of vortices is possible with sufficient amplitude of forcing at the optimum frequency. Passive lift enhancement on flexible wings is due to the self-excited wing vibrations, which occur when the frequency of wing vibrations is close to the frequency of the shear layer instabilities, and promote flow reattachment.

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Section: Small Aspect Ratio Jetsmentioning

confidence: 97%

Section: Small Aspect Ratio Jetsmentioning

confidence: 99%

Section: High-frequency Excitationmentioning

confidence: 99%

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Review of flow control mechanisms of leading-edge vortices

Gursul

Wang

Vardaki

2007

Progress in Aerospace Sciences

135

View full text Add to dashboard Cite

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“…The results were reasonably consistent with the results of earlier research in this field. The results of Bradley and Wray (6) show that, in general, an increase in C M results in an increase in lift. The work of Bradley, Wray and Smith 1 ", although carried out on arrow, delta and diamond planforms, shows the dependance of C L on chordwise nozzle position.…”

Section: Results Of Testsmentioning

confidence: 95%

“…The choked nozzle, which was similar to that used by Bradley and Wray (6) , was aligned with its axis parallel to the wing leading edge. The nozzle had an exit diameter of 0-2 in and was operated at a line pressure of 64-7 psia.…”

Section: Description Of Modelmentioning

confidence: 99%

Lift augmentation on a moderately swept wing by spanwise blowing

Clarke

1976

Aeronaut. j.

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At present it is still very difficult to predict for a given incidence, sweep-angle, leading-edge shape and Reynolds Number, whether the flow around a wing will remain attached or separate either from the upper surface as a bubble or from the leading edge as a vortex sheet which rolls up above the wing. Various attempts have been made to remove this uncertainty and it was suggested by Küchemann that it should be possible to design wings which combine coiled vortex sheets, originating from the inner part of the leading edge, with attached flow over the leading edge of the outer part of the wing. In this way some of the properties of slender wings could be combined with some properties of swept wings. His original model consisted of a swept-wing planform modified by inboard leading-edge wing strakes, the purpose of the latter being to provide the inboard vortex sheets. A similar idea has now been used in the wing design of the YF-16 lightweight fighter.

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A conceptual study of leading-edge-vortex enhancement by blowing

Cited by 2 publications

References 2 publications

Review of flow control mechanisms of leading-edge vortices

Review of flow control mechanisms of leading-edge vortices

Lift augmentation on a moderately swept wing by spanwise blowing

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