A microactuator system for the study and control of screech in high speed jets

The development of an electrostatic microactuator system for closed-loop control of screech in a high-speed jet flow system is presented in this paper. The electrostatic actuators have been fabricated using a bulk-silicon dissolved-wafer process, and are more than 10 μm in thickness needed for large stiffness in z-direction. The actuators can resonate at a frequency of about 5 kHz, consistent with the “screech” frequency, and an amplitude of 70 μm peak to peak using 20 V dc and 20 V ac drive voltage. The system consists of several of these actuators mounted at the exit lip of a high-speed jet flow system and has been shown to provide disturbances in the jet flow measured downstream from the jet nozzle. Closed-loop control strategies and experiments are underway to demonstrate control of screech