NOISE PRODUCED BY THE INTERACTION OF ACOUSTIC WAVES AND ENTROPY WAVES WITH HIGH-SPEED NOZZLE FLOWS

Some aspects of the noise generated internally by a turbojet engine are considered analytically and experimentally. The emphasis is placed on the interaction of pressure fluctuations and entropy fluctuations, produced by the combustion process in the engine, with gradients in the mean flow through the turbine blades or the exhaust nozzle. The results are directly applicable to the problem of excess noise in aircraft powerplants and suggest that the phenomenon described is the dominant mechanism. The one-dimensional interaction of pressure fluctuations and entropy fluctuations with a subsonic nozzle is solved analytically. It is found that results for a large number of physically interesting nozzles may be presented in a concise manner. An experiment is described in which one-dimensional acoustic waves and entropy waves are made to interact with a subsonic nozzle. The response of the nozzle to these disturbances is measured and compared with the response as calculated by the analytical model. The interaction of two-dimensional entropy waves with a subsonic nozzle and with a supersonic nozzle is investigated experimentally. The results are explained in terms of an analysis of the acoustic waves and entropy waves produced by a region of arbitrary heat addition in a duct with flow.

  • Corporate Authors:

    California Institute of Technology

    Jet Propulsion Laboratory
    Pasadena, CA  USA 

    Office of the Secretary of Transportation

    Office of Noise Abatement, 1200 New Jersey Avenue, SE
    Washington, DC  USA  20590
  • Authors:
    • Bohn, M S
  • Publication Date: 1976-5

Media Info

  • Pagination: 218 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00154002
  • Record Type: Publication
  • Source Agency: National Technical Information Service
  • Report/Paper Numbers: DOT/TST-76-103
  • Contract Numbers: DOT-OS-40057
  • Files: NTIS, USDOT
  • Created Date: Jun 17 2002 12:00AM