DIRECTIVITY AND SPECTRAL SOURCE NOISE CHARACTERIZATION OF COMMERCIAL AIRCRAFT DURING LANDING WITH THRUST REVERSER ENGAGEMENT

Open Access
Author:
Dunkin, Bradley Mark
Graduate Program:
Acoustics
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
April 18, 2008
Committee Members:
  • Anthony A Atchley, Thesis Advisor
Keywords:
  • aircraft noise
  • Community noise
Abstract:
Recordings of aircraft landing operations have been analyzed to obtain directivity and spectral characteristics of the noise emitted during landing with thrust reversers engaged. The recordings were made with a widely spaced microphone array positioned near and parallel to the 19R runway at Washington-Dulles International Airport in October 2004. In addition, a video camera was used to obtain positional data of the aircraft. The video is analyzed to determine the aircraft’s position and velocity as it progresses down the runway, and this position data is synchronized with the recordings. Valid acoustic data is identified by comparing it to a noise floor; then the valid data is corrected for spherical spreading, atmospheric absorption, and Doppler shift; spectral analysis is performed; and the results are combined to establish a directivity pattern. The resulting source characteristic may be used in noise modeling software to produce more accurate predictions of community noise impacts of airport operations. Aircraft types studied were Airbus 319, 320, 330, and 340; Boeing 737, 747, 757, 767, and 777; McDonnell-Douglas MD-80; and Bombardier CL-600. The source noise directivities for these aircraft were found to be nearly omnidirectional, in contrast the strong directivity of aircraft in forward-thrust operation. Spectral content was found to be dominated by low frequencies forward and aft of the aircraft, with more uniform spectra to the side of the aircraft.