DYNAMIC RECOVERY TO FULLY ATTACHED AEROFOIL FLOW FROM DEEP STALL

This paper presents results from a comprehensive analysis of pressure data from several two-dimensional aerofoil models performing constant pitch rate ''ramp-down'' motions from the fully separated state to the fully attached state. The salient observation is that, a short while after reattachment Is first observed at the leading edge, a weak distu rbance travels from the leading edge to the trailing edge, and this di sturbance causes a characteristic wave on the pressure data. The speed of the wave is uniform along the chord and is predominantly independe nt of aerofoil profile and reduced pitch rate. This contrasts with the rate of attachment, which is strongly pitch rate dependent. It is sug gested that the wave indicates convection of wake fluid over the aerof oil surface.