| Abstrakt: |
The noise output of turbojet engines has been shown [O. K. Mawardi and I. Dyer, J. Acoust. Soc. Am. 25, 389 (1953); D. M. A. Mercer and I. Dyer, Preprint 544, presented at the I. A. S. annual meeting, New York, 1954)] to correlate well with a dimensionless quantity containing the stream kinetic energy, temperature, and diameter of the jet. This paper extends these studies to include the effect on noise level of varying the operating parameters of a particular engine at a fixed rotational speed. An important cause of variation in operating parameters is change in atmospheric conditions. This paper presents charts, which, together with some details of engine performance, enable changes in noise level to be estimated. The acoustic output of an engine may vary by some 10 db, at a fixed rpm, over the range of atmospheric conditions encountered in the United States. A change of this magnitude is important when considering various problems of communication and hearing loss among engine operating personnel, and the reaction of a community to the noise stimulus. This work was supported by USAF Contract No. AF 33(616)-2151. [ABSTRACT FROM AUTHOR] |
