Active Noise Control of Bluff-Body Flows Using Dielectric Barrier Discharge Plasma Actuators

Abstract

In this experimental study DBD plasma actuators are used to control acoustic radiation from circular cylinder models in uniform cross-flow at Reynolds number of ReD = 85,000. Circular cylinders in cross-flow are chosen for study since they represent a generic flow geometry that is similar in all essential aspects to a landing gear oleo or strut. The minimization of the unsteady flow separation from the models and associated large-scale wake vorticity by using actuators reduces the radiated aerodynamic noise. Two actuation strategies are used: spanwise and streamwise oriented actuators. Near field microphone measurements and detailed study of the near wake using LDA are presented in the paper. Both spanwise and streamwise actuators give nearly the same noise reduction level of 12.6 and 14dB, respectively, and similar changes in the wake velocity profiles. The contribution of the actuator induced noise is found to be small compared to the natural shedding noise. Nomenclature D = cylinder diameter d = cylinder wall thickness D Re = Reynolds number based on cylinder diameter D St = Strouhal number based on cylinder diameter x = streamwise spatial coordinate, measured from the cylinder axis y = cross-stream spatial coordinate, measured from the cylinder axis