Development and Implementation of High Bandwidth Pulsed Microactuators for Sub and Supersonic Applications.

摘要

Unsteady actuators with a high amplitude output and tunable frequency are needed for the effective control of many sub and supersonic flows. The development, design, characterization, modeling and implementation of a novel high-bandwidth micro fluidic actuator were the main focus of this project and are described in this report. This micro fluidic actuator system essentially consists of an underexpanded primary source jet impinging upon (and exiting) a short cylindrical cavity where the array of unsteady supersonic microjets emanate through multiple micro orifices in the lower cavity surface. The frequency and amplitude response of pulsed microjets are examined in detail over a range of geometric and flow parameters, such as the source jet nozzle to cavity distance h; the nozzle pressure ratio NPR; cavity length L; actuator volume V and the inflow to outflow area ratio nSc/Sm. The results clearly show that the pulsed microjets produced by this actuator possess very high mean momentum (they are supersonic for most cases, >300 m/s) as well as a very significant unsteady component (more than 30% of the mean velocity). By proper selection of the geometric and fluid parameters, the actuator frequency can be fine tuned to any value in between 100 Hz-60 kHz.