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New Type of Tip Jet to Reduce Noise
Published online by Cambridge University Press: 26 October 2023
Extract
During the past few years, it has become recognised that one of the major objections to the introduction of helicopters fitted with pressure jets at the blade tips is the high level of noise set up by the jets The source of this noise lies m the jet stream itself When air travelling at high speed mixes with the surrounding air, turbulence is formed in the region of high velocity shear and noise is emitted into the stationary or near stationary medium surrounding the jet The large velocity gradient or shear actually amplifies the sound (Ref 1) which increases as a very high power of the jet velocity, normally about the eighth power Needless to say, if turbulence exists initially in the jet stream, either from poor internal shaping of the engine or from incomplete burning of the fuel, the noise will be aggravated and a different noise law achieved With well designed jet umts, however, the eighth power law is obeyed surprisingly well
- Type
- Research Article
- Information
- The Journal of the Helicopter Association of Great Britain , Volume 9 , Issue 3 , January 1956 , pp. 404 - 413
- Copyright
- Copyright © Royal Aeronautical Society 1956
Footnotes
This Paper was submitted by the Author as a written contribution for the Journal and is printed with the permission of the University of Southampton
References
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