Control of flow on helicopter rotor blades under quasi-steady and unsteady conditions using smart air-jet vortex generators

Low-speed wind tunnel experimental investigations were conducted to explore the use of smart air-jet vortex generators (AJVGs) to delay flow separation over a rotor blade section under quasi-steady and unsteady flow conditions. Utilising only a small amount of continuous blowing (0.0%<Cμ<1.0%), we have been successful in suppressing the formation of the dynamic stall vortex (and the corresponding break in the pitching moment curve) of an oscillating RAE 9645 aerofoil. We have also found that we can reduce the mass flux (and ensuing momentum) requirement of AJVGs by means of pulsing whilst simultaneously maintaining performance enhancements attributable to steady AJVGs on a quasi-steady NACA 23012C aerofoil.