Separation and Circulation Control on an Elliptical Airfoil by Steady Blowing

The application of blowing over a thick elliptical airfoil is considered for the purpose of identifying the hierarchy of additional parameters affecting the flow, such as slot width, its location, and orientation, in addition to the mass and momentum flow that were considered as being significant in the past. When a single jet emanates from a narrow slot at a prescribed location, the incremental lift coefficient scales mostly with the momentum coefficient (C_µ). For wider slots, the slot width has to be considered as an independent parameter even when the jet velocity is much higher than the freestream. The lift increment depends strongly on the slot location when the latter is near the natural separation location of the flow, but it is independent of Reynolds number. Deleterious effects of steady blowing on C_L were observed for low momentum inputs. For wider slots located upstream of the natural separation location, the drag is sensitive to Reynolds number and it is not solely affected by C_µ. Flowfield measurements are used to explain some of the observations made.