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Starting vortex
About: Starting vortex is a research topic. Over the lifetime, 4785 publications have been published within this topic receiving 100419 citations.
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TL;DR: In this article, an experimental investigation of the interaction between streamwise discrete vortices and oblique shocks formed over a two-dimensional wedge surface was conducted in a Mach 3 blowdown wind tunnel.
Abstract: An experimental investigation of the interaction between streamwise discrete vortices and oblique shocks formed over a two-dimensional wedge surface was conducted in a Mach 3 blowdown wind tunnel. An instrumented two-dimensional wedge was placed downstream of a semiispan wing so that the trailing tip vortex would arbitrarily interact with the shock wave formed over the wedge surface. The experiments were designed to simulate interaction of streamwise vortices from upstream bodies with shock waves formed over aft surfaces as might be encountered in supersonic flight of aircraft and missiles. The influence of vortex strength and vortex-airfoil vertical separation distance on the interaction was examined.
32 citations
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29 Jul 2013
TL;DR: A wind tunnel test was conducted in the NASA Langley Transonic Dynamics Tunnel (TDT) on a six percent thick slightly cambered elliptical circulation control airfoil with both upper and lower surface blowing capability as discussed by the authors.
Abstract: A wind tunnel test was conducted in the NASA Langley Transonic Dynamics Tunnel (TDT) on a six percent thick slightly cambered elliptical circulation control airfoil with both upper and lower surface blowing capability. Parametric evaluations of jet slot heights and Coanda surface shapes were conducted at momentum coefficients (Cm) from 0.0 to 0.12. Test data were acquired at Mach numbers of 0.3, 0.5, 0.7, 0.8, and 0.84 at Reynolds numbers per foot of 2.43 x 105 to 1.05 x 106. For a transonic condition, (Mach = 0.8 at alpha = 3 degrees), it was generally found the smaller slot and larger Coanda surface combination was overall more effective than other slot/Coanda surface combinations. Lower surface blowing was not as effective as the upper surface blowing over the same range of momentum coefficients. No appreciable Coanda surface, slot height, or slot blowing position preference was indicated transonically with the dual slot blowing.
32 citations
TL;DR: In this article, the qualitative and quantitative behavior of double row vortical structures in the near field region of a plane wall jet are studied experimentally by flow visualization and hot-wire measurements.
Abstract: The qualitative and quantitative behaviour of double row vortical structures in the near field region of a plane wall jet are studied experimentally by flow visualization and hot-wire measurements Ensemble averaging is employed to investigate the interaction of vortices with the wall In the flow visualization study, a double row vortical structure, which includes a primary vortex formed in the outer layer region and a secondary vortex induced in the inner layer region, and the vortex lift-off phenomenon are clearly observed during the development of the wall jet The phase averaged results of the velocity measurements show that the instability leading to induction of the secondary vortex is stimulated by the primary vortex In the early stage of wall jet transition, the inflection point of the inner layer velocity profile moves transversely from the wall surface to the inner layer region due to passage of the well-organized primary vortex in the outer layer region The inner layer instability is thus induced and the instability wave rolls up to form the secondary vortex Furthermore, the secondary vortex will convect downstream faster than the primary vortex, and this difference in convective speed will lead to the subsequent phenomenon of vortex lift-off from the wall surface
32 citations
TL;DR: The existence of global steady vortex rings in an ideal fluid with given propagation speed W > 0, flux constant k ⩾ 0 and any bounded, positive, non-decreasing vorticity function was proved in this article.
32 citations
TL;DR: In this article, a leading-edge vortex was observed on the suction surface of the plate, and its evolution and circulation were characterized with variations in angle of attack, Reynolds number, and azimuthal and spanwise positions.
Abstract: Particle image velocimetry was used to characterize the flowfield on flat plates of aspect ratios 2 and 4 undergoing a starting rotation motion at Reynolds numbers, based on tip velocity, of 4,000, 8,000, and 16,000. The starting motion was performed in a tank of quiescent water. For both aspect ratios, a leading-edge vortex was observed on the suction surface of the plate, and its evolution and circulation were characterized with variations in angle of attack, Reynolds number, and azimuthal and spanwise positions. A region of strong counter-rotating vorticity was also observed between the leading-edge vortex and the plate surface, which becomes entrained by the leading-edge vortex. The circulation of the leading-edge vortex, when rendered dimensionless by the plate chord length and tip speed, was found to be relatively insensitive to Reynolds number and the azimuthal position of the plate within the ranges of the measurements; however, a strong (approximately linear) dependence on angle of attack was obs...
32 citations