This note describes the experimental finding of counter-rotating structures, with axes oriented approximately spanwise, located between the surface and the vortex core on a 60-deg delta wing at high incidence. The finding is explained using laser sheet flow visualization and spectral analysis of hot-film data on and above the surface. It is cofirmed by quantitative analysis of velocity data, synchronized in phase to the signal from a hot film. The finding is related to previous work on the origin and effects of such fluctuations, and its implications explored. (1) Viewed in a plane parallel to the wing surface, surface layer streaklines oscillated at a frequency that matched that of the spectral peak measured using hot-film anemometry. (2) Viewed in a vertical plane along a ray inboard of the secondary separation line, the streaklines rolled up and erupted off the surface, indicating counter-rotating structures. (3) Spectra measured using LV (laser velocimetry) above the surface matched those measured by a surface hot film. (4) Velocity measurements, triggered from the surface hot-film signal, resolved into the phase of the spectral peak frequency and ensemble averaged, showed organized, counter-rotating structures in two vertical planes aligned with rays. These clearly indicate vortical structures whose axes are oriented approximately spanwise, convecting at a speed of roughly 0.15 U(Ind infinitely). (5) The nature of the structure appears consistent with a centrifugal instability arising between the primary vortex and the surface.
Counter-rotating structures over a delta wing
Die sich über die Deltaflügeloberfläche gegenläufig drehenden Wirbelstrukturen
AIAA Journal ; 34 , 9 ; 1958-1960
1996
3 Seiten, 3 Bilder, 2 Tabellen, 10 Quellen
Article (Journal)
English
Tragflügelumströmung , Wirbelströmung , Flügeloberseite , Wirbelablösung , Gegenlauf , Wirbelkern , Anstellwinkel (Tragflügel) , Vergleichsmessung , Laser , sichtbare Strömung , Spektrometrie , Hitzdrahtanemometer , Strömungsgeschwindigkeitsmessung , Fernsehkamera , Rauch , Vektor , Schwingung , Frequenz , Instabilität
Counter-rotating structures over a delta wing
AIAA | 1996
|Counter-Rotating Structures over a Delta Wing (TN)
Online Contents | 1996
|Comment on "Counter-Rotating Structures over a Delta Wing" (RF)
Online Contents | 1997
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