ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06

1pNS8. Experimental investigation of low-frequency noise from jet engine test cells.

Robert G. Gibson

Wyle Labs., 2001 Jefferson Davis Hwy., Ste. 701, Arlington, VA 22202

Low-frequency noise emission from facilities designed for the ground runup testing of jet engines can be a source of annoyance to communities near military air bases. Noise measurements, using arrays of microphones and accelerometers at a number of U.S. Air Force hush houses, provide information regarding the source characteristics. Comparisons are made between noise from a single aircraft both inside and outside a hush house. Source location calculations indicate that low-frequency noise originates from a region near the trailing edge of the jet exhaust deflector. Coherence between selected near-field and far-field sensors is found to be sufficiently high to warrant experimental investigation of the active reduction of noise from a full scale hush house, using feedforward control techniques, following on from the small scale hush house experiments described by J. P. Smith et al. [ 3332(A) (1994)]. [Work sponsored by the U.S. Air Force.]