Aerodynamics of delta wings with leading edge blowing

Tavella, Domingo

doi:10.2514/6.1986-2230

Cited by 3 publications

(3 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This is a non-intrusive fullfield measurement technique by tracking speckling patterns on the surface of an object in timeaccurate consecutive image pairs through a correlation method [14,15]. It has been previously used in our laboratory for membrane wings [16], flags on airfoils [9,10], on finite wings [11], and in freestream [17]. A highspeed DIC system was used to provide time-accurate three-dimensional flag deformation.…”

Section: Flag Deformationmentioning

confidence: 99%

“…Recently it was shown that self-excited oscillations of a small flag attached at the leading-edge of a two-dimensional airfoil at post-stall angles of attack could excite the separated shear layer, induce periodic shedding of leading-edge vortices and lead to increased time-averaged lift force [9]. The frequency of the flag oscillations could be tuned to the frequency of the flow instabilities by properly choosing the properties of the flag [10,11]. For the case of nominally two-dimensional post-stall flows over airfoils and high-aspect-ratio unswept wings, the main flow instability that flags lock-in is the wake instability.…”

Section: Introductionmentioning

confidence: 99%

“…This is expected because the flags interact with the three-dimensional vortical structures shed from the leading-edge, which implies varying dominant frequency in the chordwise and spanwise directions. It is noted that, for a tapered wing with unswept leading-edge and swept trailing-edge [11], both full-span and part-span flags attached to the leading-edge of the wing exhibited significant three-dimensionality and phase-lags. The effect of the three-dimensional flow is expected to be more significant for delta wings.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Passive Poststall Flow Control on Nonslender Delta Wings Using Flags

Tan,

Wang,

Gursul

2024

AIAA Journal

View full text Add to dashboard Cite

The lift force on two nonslender delta wings with sweep angles of [Formula: see text] and [Formula: see text], with flags attached to the leading edge, was investigated. Substantial lift enhancement in the poststall regime of the clean wings and the stall delay were observed. With a flag, the flowfield measurements showed the reattachment of the shear layer onto the wing surface and the re-formation of the leading-edge vortex, whereas the clean wing had completely stalled flow at the same angle of attack. Over a wide range of angles of attack, mass ratios, and flag lengths, the maximum lift enhancement was attained when the dimensionless frequency of flag oscillations was in an optimal range and the flag-tip velocity had sufficient amplitude. The optimal dimensionless frequency range corresponded to the natural shear layer instabilities of the clean wing. The excitation in this range substantially increased the coherency of the separated flow due to the flag oscillations. The main mechanism of the lift increase is the excitation of the shear layer, which exhibits convective instability. This is very different from the lift enhancement mechanism on airfoils where the flags lock-in to the wake instability, which is known to have an absolute instability at the poststall angles of attack of the clean airfoil.

show abstract