Control of Fluid-Structure-Sound Interaction Mechanisms by Means of Synthetic Jets

The effectiveness of feedback control technique in suppressing flow-excited oscillations is illustrated by considering several examples of fluid-structure-sound interaction mechanisms. These include impinging flow oscillations, flow-excited acoustic resonance, vortex-induced lock-in vibration and turbulent buffeting vibration. The control actuator in all examples consists of a synthetic jet issuing from a narrow slit positioned at the location of flow separation. The synthetic jet is generated by loudspeakers, which are activated by the signal of a sensor monitoring the system response. Different types of controllers are used to properly adjust the phase and the gain of the speaker signal with respect to those of system response. Different sensors are also employed to investigate the effect of sensor type on the control performance. The developed technique proved to be very effective; reducing the oscillation amplitudes by amounts reaching 35dB.