Studies on the Resonance-Enhanced Micro-Actuator with Active Structures

The need for actuators that are adaptable for use in a wide array of applications has been the motivation behind actuator development research over the past few years. At the Advanced Aero Propulsion Laboratory at the Florida State University, a novel, fluidic-based micro-actuator has been developed that produces pulsed, supersonic microjets by utilizing a number of micro-scale, flow/acoustic resonance phenomena. This Resonance-Enhanced Microjet (REM) actuator has been tested for flow and noise control in a few flowfields in an open loop manner only. In order to use this actuator in a closed loop, feedback control system, a modified design that incorporates smart materials is being studied. In the design explored here, a set of piezoelectric ceramic stack actuators (piezo-stacks) are integrated to actively control part of the geometry, thus producing changes in the micro-actuator’s resonance frequency. By controlling the voltage applied to the piezo-stacks, the frequency of this actuator can be actively and rapidly (1 ms) tuned over a very large range: frequency shifts greater than 1 kHz are attainable with the current design. The piezoelectric stacks are also shown to enable closed loop control of the micro-actuator’s frequency, a nontrivial task for fluidic-based actuators.