Active Jet Noise Control
Final technical rept. 15 Feb 2001-31 Mar 2002
FLORIDA STATE UNIV TALLAHASSEE DEPT OFMECHANICAL ENGINEERING
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A novel high-speed jet noise suppression technique using high-pressure gas microjet injection at the nozzle exit was developed with promising results using the laboratory scale jet. The main jet parameters, the nozzle pressure ratio and the temperature ratio are chosen to correspond with realistic engine operating conditions. Keeping in mind the applicability of the technique to full-scale engines, the microjet mass flow was kept at less than 2 of the primary jet mass flow. The A-weighted spectrum with appropriate scaling to reflect the full-scale nozzle show a 6 dBA reduction in the peak noise radiation direction. An attempt is made during this investigation to develop Active Noise Control methods for cancellation of broadband jet noise. A demonstration of successful control architecture has been accomplished using the colored random noise cancellation. An actuator based on pulsed microjet appears to be most promising for the current application. A specially designed micro valve operating at high pressures and high frequencies was developed and tested successfully. The valve was able to provide a pulsed jet operating at nozzle exit mean pressure of about 45 sia at 2000 Hz.
- Jet and Gas Turbine Engines