Dynamic Stall Control on Rotor Airfoil via Combination of Synthetic Jet and Droop Leading-Edge

A novel strategy of dynamic stall control for rotor airfoil via combinational method by using variable-droop leading edge (VDLE) and synthetic jet is numerically investigated. As foundations, body-fitted grids around oscillatory rotor airfoil with VDLE are regenerated by reconstruction of airfoil and solution of Poisson equations, and the unsteady flowfield around airfoil is simulated by solving RANS equations. To improve the computational accuracy and efficiency, the ROE-MUSCL scheme, k-ε SST turbulence model and implicit LU-SGS scheme are adopted. Additional, a suction/blowing type boundary condition is established to simulate the periodic synthetic jet. Based upon the CFD method, verified results indicate that dynamic stall vortex could be significantly suppressed by individual VDLE and synthetic jet, and the combinational method could further improve aerodynamic characteristics of airfoil comparing to individual control method. Furthermore, parametric analyses on dynamic stall control of airfoil by combinational method are conducted, and it indicates that aerodynamic characteristics of an oscillatory rotor airfoil could be significantly improved when non-dimensional frequency (k*) of VDLE is about 1.0, and larger base droop angle and angular amplitude helps to suppress flow separation over airfoil. At last, the combinational control method preliminarily applied on rotor blade is numerically simulated.