Analysis of Co-Flow Jet Effect on Dynamic Stall Characteristics Applying to Rotor Airfoils

Abstract

The performance of helicopter is limited by the phenomenon of dynamic stall. Dynamic stall is attributed to the time-varying angle of attack (AOA) of blade element resulting from blade flapping cyclic pitch inputs and wake flow. Co-flow jet(CFJ), as a novel flow control technique proposed by the joint research team from University Miami (UM) and AFRL has shown great improvement on lift enhancement, drag reduction due to its strong circulation improvement and turbulent mixing effect. Focusing on dynamic stall characteristics, this paper studies the effect of co-flow jet technique applying to rotor airfoil OA309. Numerical simulations show that CFJ can remove dynamic stall phenomenon occurring on rotor airfoils but the momentum coefficient should be carefully chosen so as to obtain high-efficient control effect.