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The ability of a particular type of MEMS-based mechanical actuators to excite the shear-layer of a highspeed axisymmetric jet has been examined. This study focused on the utilization of a single actuator which is intended for use, as part of an array of actuators distributed around the jet lip, for the purpose of screech noise cancellation. Measurements of the streamwise velocity spectra on the shear layer centerline demonstrated the ability of the micron-size actuators to introduce disturbances into the shear layer up to a Mach number of 0.6. When the actuator oscillation frequency was close to the most unstable frequency of the shear layer, the disturbance magnitude exceeded that produced by acoustic and glow discharge forcing in other investigations. The ability of the MEMS actuator with its small amplitude and force to produce a strong disturbance was attributed to the direct mechanical action of the actuator on the shear layer at the highreceptivity point at the jet lip. It was demonstrated that an optimal radial actuator position exists where the actuator is within tens of microns from the jet lip. Finally, video records of the MEMS operation showed that the actuator operates properly and without being damaged under screech conditions.

Arrays of MEMS-based actuators for control of supersonic jet screech