Variable structure model for flow-induced tonal noise control with plasma actuators

The objective of this work was to study the effect of plasma actuators in attenuating low-speed flow-induced cavity tones from a control point of view by employing techniques from classical control. A modification of the existing physics-based linear model produced a new variable structure model in which a plasma actuator was regarded as a linear gain. The parameters of the overall model working at two operating voltages were identified using experimental data. The effects of the plasma actuator control at other various operating voltages were thus able to be predicted using linear interpolation. The good agreement between the predicted and the measured data supported the proposed variable structure model, inside of which plasma actuators affected the damping of cavity pressure oscillations proportionally to the applied voltage to reduce flow-induced-tonal noise. With the proposed variable structure model the system stability controlled by plasma actuators at various operating voltages was ensured, thus a closed-loop control method could be applied without leading to instability. A simple proportional integral derivative controller was implemented. Results show the potential of a closed-loop method by increasing system power efficiency.