Accession Number:

ADA001329

Title:

Near Field Noise Prediction for a Linear Array of Turbojet Engines.

Descriptive Note:

Final rept.,

Corporate Author:

AIR FORCE FLIGHT DYNAMICS LAB WRIGHT-PATTERSON AFB OHIO

Report Date:

1974-07-01

Pagination or Media Count:

77.0

Abstract:

A computer program is presented for calculating the sound pressure level SPL in the jet near field which accounts for ground reflection and multiple engine operation. The prediction method is a modification of the semi-empirical technique presented in AFFDL TR-67-43 Near Field Noise Analysis of Aircraft Propulsion Systems with emphasis on Prediction Techniques for Jets. The modifications in addition to accounting for ground reflection allow the prediction of the SPL for the overall and three octave bands at any point in the field and require data inputs of jet exit temperature, Mach number and diameter. A brief description is presented of a noise measurement program conducted on the XB-70 aircraft during which one-third octave band noise spectra were obtained for a range of engine conditions and for various combinations of linear arrays of engines.

Subject Categories:

  • Aircraft
  • Acoustics
  • Jet and Gas Turbine Engines

Distribution Statement:

APPROVED FOR PUBLIC RELEASE