Tone noise reduction by plasma actuator on a flat plate with blunt trailing edge

Abstract

An experimental study of active control of vortex shedding narrow band tonal noise from both blunt and rounded trailing edge of a profiled body at zero incidences was performed using Single Dielectric Barrier plasma actuators (DBD). Acoustics and flow measurements were carried out in an open jet, aerocoustic wind tunnel at Reynolds numbers ranging from 7x104 to 4x105. The noise results were obtained using single microphone, while both PIV and hot-wire were used for flow measurement in order to further understand the flow control mechanism behind the noise reduction. Three configurations of plasma actuators were investigated, tangential wind actuation (PA1), downward wind actuation (PA2), and spanwise wind actuation (PA3). The noise results suggest that plasma actuator (PA1) is less effective for vortex shedding tonal noise reduction compared with the other configurations. On the other hand the second tested configuration (PA2) showed ability to attenuate vortex shedding tonal noise by 15 dB at 7.5 ms-1. While the last configuration (PA3), demonstrate the ability to reduce the tonal noise by 8dB. In addition, hot-wire and PIV results revealed that the generated electric wind under the current experimental conditions does not eliminates the vortices, but reduces their strength, makes them extended, and reduces the turbulence intensity in the wake region which leads to a reduction in the fluctuating component of the drag coefficient.