A STUDY OF THE PREDICTION OF CRUISE NOISE AND LAMINAR FLOW CONTROL NOISE CRITERIA FOR SUBSONIC AIR TRANSPORTS

General procedures for the prediction of component noise levels incident upon airframe surfaces during cruise are developed. Contributing noise sources are those associated with the propulsion system, the airframe and the laminar flow control (LFC) system. Transformation procedures from the best prediction base of each noise source to the transonic cruise condition are established. Two approaches to LFC/acoustic criteria are developed. The first is a semi-empirical extension of the X-21 LFC/acoustic criteria to include sensitivity to the spectrum and directionality of the sound field. In the second, the more fundamental problem of how sound excites boundary layer disturbances is analyzed by deriving and solving an inhomogeneous Orr-Sommerfeld equation in which the source terms are proportional to the production and dissipation of sound induced fluctuating vorticity. Numerical solutions are obtained and compared with corresponding measurements. Recommendations are made to improve and validate both the cruise noise prediction methods and the LFC/acoustic criteria.

• Corporate Authors:

  Lockheed-Georgia Company

  Marietta, GA  United States 
• Authors:
  • Swift, G
  • Mungur, P
• Publication Date: 1979-8

Media Info

• Pagination: 262 p.

Subject/Index Terms

• TRT Terms: Acoustics; Aerodynamic noise; Aircraft noise; Airframes; Boundary layer; Cruising flight; Forecasting; Laminar flow; Mathematical prediction; Noise; Noise sources; Propulsion; Subsonic aircraft; Transport aircraft; Vehicle power plants
• Uncontrolled Terms: Propulsion systems
• Old TRIS Terms: Aeroacoustics; Boundary layer control; Cross flow; Orr-sommerfeld equations; Propulsion system configurations; Tollmein-schlichting waves; Vorticity
• Subject Areas: Aviation; Environment; Vehicles and Equipment;

Filing Info

• Accession Number: 00312765
• Record Type: Publication
• Source Agency: National Technical Information Service
• Report/Paper Numbers: NASA-CR-159104 Final Rpt., LG78ER0218
• Contract Numbers: NAS1-14946
• Files: TRIS
• Created Date: May 7 1980 12:00AM