On the use of relative velocity exponents for jet engine exhaust noiseThe effect of flight on jet engine exhaust noise has often been presented in terms of a relative velocity exponent, n, as a function of radiation angle. The value of n is given by the OASPL reduction due to relative velocity divided by 10 times the logarithm of the ratio of relative jet velocity to absolute jet velocity. It is shown in this paper that the exponent n is positive for pure subsonic jet mixing noise and varies, in a systematic manner, as a function of flight conditions and jet velocity. On the basis of calculations from simple empirical models for jet mixing noise, shock noise and internally-generated noise, it is shown that when other sources are present, the resulting range of n is increased over the range for jet mixing noise, and in some cases negative values of n are obtained.
Document ID
19780053774
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Stone, J. R. (NASA Lewis Research Center Cleveland, Ohio, United States)
Date Acquired
August 9, 2013
Publication Date
May 1, 1978
Subject Category
Aircraft Propulsion And Power
Meeting Information
Meeting: Meeting of the Acoustical Society of America