Flow Reattachment and Vortex Re-formation on Oscillating Low-Aspect-Ratio Wings

Control of Separated Flow over Swept Missile Fin Using Pitching Oscillations

“…These results are consistent with the experimental observation of Vardaki et al [3], who have shown that applying a sinusoidal pitching motion to a 50 sweep delta wing at the same incidence as in the current study and for F varying from 1 to 2 results in the acceleration of the longitudinal flow and in the reformation of the leading-edge vortex for 1 . Nevertheless, in the current study, the study of the flow in transverse planes has evidenced that the leading-edge vortex is not regenerated.…”

“…In fact, an increase of the Reynolds number induces a faster vortex breakdown and then the disappearance of the leadingedge vortex. In our study, the Reynolds number based on the root chord of the wing equals 5:8 10 6 , whereas it ranges between 13,000 and 30,000 in the experimental works of Vardaki et al [3]. One can then assume that the regeneration of the leading-edge vortex is more difficult in our case than in [3].…”

“…The frequency is set equal to F 1:5, which corresponds to the natural vortex shedding frequency in the unforced case. It should be remembered here that Vardaki et al [3] have shown that this control strategy is efficient in a range of F varying from 1 to 2. It should be also underlined here that flexible wings self-exited at the same frequencies also delay moderately sweep wing stall [15].…”

“…Pitching oscillations appear to be a promising mean to control the flow over such wings. Indeed, encouraging results have been obtained experimentally at low Reynolds and Mach numbers [3,4]. The goal of this study is then to extend the range of applicability of this type of control.…”

“…It has been experimentally shown by Vardaki et al [3] and Cipolla and Rockwell [4] that applying a sinusoidal pitching motion to a stalled moderately swept delta wing can reduce the intensity of the reverse flow over the wing and can also regenerate the leading-edge vortex. As a consequence, the wing stall is delayed and the lift force increases.…”