Active Flow Control Strategy on Improving Aerodynamic Characteristics of Rotor

Abstract

A new active flow control strategy by placing a synthetic jet actuator (SJA) and a trailing-edge flap (TEF) has been proposed, and its control effects on mitigation of large negative pitching moments and drag caused by rotor dynamic stall are numerically investigated by CFD method. A moving-embedded grid method and an unsteady Reynolds averaged Navier–Stokes (URANS) solver are established for predicting the complex flowfields of rotor and airfoil. Calculated results of VR-12 and SC1095 airfoils indicate that TEF and SJ can suppress the formation of dynamic stall vortex and postpone flow separation over rotor airfoil, resulting in much lower Cdmax and Cmmax comparing to the baseline state, and aerodynamic characteristics of airfoil could be further improved by the new control method comparing to individual control method. Furthermore, parametric analyses on dynamic stall control of airfoil by the 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 TEF is about 1.0, and larger angular amplitude help to increase the lift coefficient. At last, simulations are conducted for the flow control of rotor airfoil by the combinational method, and the numerical results indicate that the TEF can better improve the lift characteristics of rotor airfoil, and synthetic jet further increases the aerodynamic characteristics of rotor airfoil.