Accession Number : ADA317299

Title :   A Microactuator/Microsensor System For The Study And Control of Screech in High Speed Jets.

Descriptive Note : Final rept. 1 Jun 94-31 May 96,

Corporate Author : MICHIGAN UNIV ANN ARBOR

Personal Author(s) : Najafi, Khalil

PDF Url : ADA317299

Report Date : 01 SEP 1996

Pagination or Media Count : 21

Abstract : A novel Micro-Electro-Mechanical Actuator was designed, fabricated, and tested for the control of screech in high-speed jets. It was used at the exit of a supersonic axisymmetric jet for the introduction of perturbations into the convectively unstable supersonic shear layer. The 14- micron thick electrostatic microactuator was fabricated using bulk micromachining from a boron- doped silicon wafer which was bonded to a support glass substrate. The actuator could be forced into mechanical resonance at a frequency of 5kHz at an amplitude of more than 70 microns peak-to-peak using a 20V DC and a 20V AC voltage drive. The actuator and its sense and drive electronics were mounted on a printed circuit board, and several of these boards were mounted at the exit lip of a high-speed jet flow system. The entire system was tested at different jet speeds of up to 100 mis, and disturbances were introduced into the jet flow as measured using hot wire anemometers placed downstream from the jet nozzle. Two different actuator designs were fabricated, with the second providing better resistance to breakage at high speeds. Ongoing investigations are aimed at developing a technique to modify, and ultimately control, the feedback loop responsible for the creation of screech.

Descriptors :   *MECHANICAL PROPERTIES, *DETECTORS, *ACTUATORS, VELOCITY, MACHINING, HIGH VELOCITY, SUBSTRATES, GLASS, FEEDBACK, SILICON, RESONANCE, AXISYMMETRIC, NOZZLES, PERTURBATIONS, DOPING, FLOW, WAFERS, BORON, LOOPS, JET FLOW, DRIVES(ELECTRONICS), PRINTED CIRCUIT BOARDS, HOT WIRE ANEMOMETERS, SUPERSONIC AIRCRAFT, MINIATURE ELECTRICAL EQUIPMENT, MICROMINIATURIZATION.

Subject Categories : Mfg & Industrial Eng & Control of Product Sys
      Optical Detection and Detectors

Distribution Statement : APPROVED FOR PUBLIC RELEASE