Effect of Synthetic-Jet Actuation on Airfoil Acoustic Radiation

Synthetic jet actuators (SJAs) have been primarily investigated as means of unsteady flow control on aircraft wing. The current work for the first time explores the effectiveness of SJAs for control of a low-speed airfoil acoustic radiation both with the uniform upstream flow conditions (with noise dominated by the trailing-edge sources) and in the presence of an upstream flow disturbance (with noise dominated by the leading-edge sources or stall-related phenomena depending on the disturbance character and amplitude). In the high-fidelity numerical study, the effect of the selected SJA location and other parameters characterizing SJA performance are determined. In the adopted numerical procedure, the actuator is modeled without its resonator cavity through imposing a simple fluctuating-velocity boundary condition at the bottom of the actuator’s orifice. The orifice cavity with the properly defined boundary condition is then embedded into the airfoil surface for conducting high-accuracy viscous analysis of SJA-based active noise control. The effects of the actuation on sound radiated by the airfoil both in presence and absence of the upstream flow disturbance are examined for a benchmark problem of time-harmonic gust interaction with a symmetric Joukowski airfoil.