Some Results of Experiments Relating to the Generation of Noise in Jets

Abstract

Some sample experimental results relating to the nature and sources of noise in jets are presented. Previous work is extended to include more detailed information about the jet structure. In this regard noise data are compared for jets having somewhat different turbulence profiles. High temperature jets are noted to have different radiation patterns and to be more efficient noise radiators than low temperature jets. Noise data for the high temperature supersonic jet of a rocket engine are included for comparison with those of subsonic jets. Some experiments have shown the noise levels at the low frequencies can be markedly reduced by the use of grids in the jet stream.