AXIAL SOURCE STRENGTH DISTRIBUTION IN SUBSONIC JETS

Axial acoustical source strength distributions of subsonic jets have been investigated using a directional microphone system in an anechoic chamber. The directional microphone system uses the imaging principle of a spherical concave reflector and is diffraction limited thereby resulting in a loss of resolution. A special numerical method has been developed to recover the 'apparent' axial source strength distribution from the diffracted data. Measurements have been performed in the far field of 1/2 inch, 1 inch, and 2 inch diameter jets operating at exit Mach numbers ranging from 0.7 to 1. Results are presented for source strength distribution along the jet and spectra of noise radiated from localized regions of the jet. These results are then integrated to obtain the overall noise intensity and spectrum for comparison with measurements obtained by means of a single non-directional far field microphone.

• Corporate Authors:

  University of Southern California, Los Angeles

  Los Angeles, CA  United States  90089

  Office of the Secretary of Transportation

  1200 New Jersey Avenue, SE
  Washington, DC  United States  20590
• Authors:
  • Chu, W T
  • Kaplan, R E
  • Laufer, J
• Publication Date: 1976-9

Media Info

• Pagination: 35 p.

Subject/Index Terms

• TRT Terms: Acoustic measuring instruments; Acoustic signature; Acoustics; Far field; Flow fields; Jet propelled aircraft; Noise; Nozzles; Subsonic flow
• Uncontrolled Terms: Jets
• Old TRIS Terms: Acoustic measurement; Noise sound; Subsonic nozzles
• Subject Areas: Aviation; Environment;

Filing Info

• Accession Number: 00169251
• Record Type: Publication
• Source Agency: National Technical Information Service
• Report/Paper Numbers: USCAE-129, DOT-TST-76T-41
• Contract Numbers: DOT-OS-00002
• Files: NTIS, USDOT
• Created Date: Feb 16 2002 12:00AM