Features of flow control in a rectangular shallow cavity using a barrier discharge using feedback

For the first time, various modes of tonal noise suppression in a shallow cavity were investigated using a plasma actuator in a feedback circuit. The studies were carried out for a flow velocity of $37$ m/s and a Reynolds number of $120\,000$. At $12$ dB reduction in the amplitude of resonance pressure fluctuations on the rear wall of the cavity was demonstrated. It is shown that the operation of the discharge as part of the feedback system allows reducing the energy input into the discharge by $2.5$ times to $50$ W/m. Visualization of the velocity field using the phase-locked PIV method made it possible to reconstruct the evolution of coherent structures in the shear layer of the cavity. The period of coherent structures in the shear layer corresponds to the spectrum of pressure fluctuations in the cavity.