Bluff Body Noise and Flow Control with Atmospheric Plasma Actuators

Plasma actuators operating in atmospheric air were employed to modify aerodynamic flow over a bluff body. The model consisted of a cylinder and a torque link that was installed on the lee side of the cylinder. The objective was to reduce the broadband noise that is mainly generated by the impingement of the cylinder wake on the torque link. The plasma actuators were configured to produce dielectric barrier discharges, through which the flow separation from the cylinder was enhanced by the externally imposed body force. As a result the flow-structure interaction between the wake and the torque link was reduced, leading to the attenuation of broadband noise. The noise and flow control performance with the plasma actuators were studied in an anechoic chamber facility as well as in a wind tunnel facility by examining sound pressure and mean flow field respectively. With the current plasma actuators, it was found that there was 1 dB reduction in overall sound pressure level at a free stream speed of 30 m/s, and the wake speed impinging on the torque link was reduced. A possible solution to improve the broadband noise attenuation performance is discussed at the end of this paper.