Alteration of separated-flow structure achieved through a local action

Abstract

Results of an experimental study of a subsonic flow past a straight-wing model installed at fixed angle of attack in hysteresis range of flow velocity are reported. It was shown that, at the same angle of attack and at one and the same flow velocity, flows of two types are possible on the upper surface of the model, leading-edge flow stall and re-attached flow with laminar-turbulent transition in the vicinity of the leading edge. It was found that the wing flow could be transformed from stalled to re-attached one with the help of a local influence applied at one point on the model inside the stall zone. Visualization data for both flows, hot-wire anemometer measurements of flow velocity, and measurements of the amplitude and frequency spectra of flow pulsations in both flows, are reported.