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image/svg+xml Jakob Voss, based on art designer at PLoS, modified by Wikipedia users Nina and Beao Closed Access logo, derived from PLoS Open Access logo. This version with transparent background. http://commons.wikimedia.org/wiki/File:Closed_Access_logo_transparent.svg Jakob Voss, based on art designer at PLoS, modified by Wikipedia users Nina and Beao zbMATH Openarrow_drop_down
image/svg+xml Jakob Voss, based on art designer at PLoS, modified by Wikipedia users Nina and Beao Closed Access logo, derived from PLoS Open Access logo. This version with transparent background. http://commons.wikimedia.org/wiki/File:Closed_Access_logo_transparent.svg Jakob Voss, based on art designer at PLoS, modified by Wikipedia users Nina and Beao
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Article
Data sources: zbMATH Open
AIAA Journal
Article . 1977 . Peer-reviewed
Data sources: Crossref
https://doi.org/10.2514/6.1976...
Article . 1976 . Peer-reviewed
Data sources: Crossref
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High-Frequency Broadband Rotor Noise

High-frequency broadband rotor noise
Authors: George, A. R.; Kim, Y. N.;

High-Frequency Broadband Rotor Noise

Abstract

A method has been developed to find the absolute spectral level of high frequency far field sound of a rotor in terms of random load fluctuations on the rotor blades. The analysis deals with frequencies where the radiated sound spectrum is smooth, i.e., above 300 to 400 Hz for a typical helicopter. This is in constrast to the low frequency regions where the spectrum is continuous but peaked near bladed passing harmonics. We first show that the smooth, broadband part of the spectrum corresponds to load fluctuations which are uncorrelated between blade passages. Then the spectral intensities from the individual blades are additive. A point load approximation with spanwise loading corrections is used and the blade loading spectrum is specifically derived for upwash fluctuations due to inflow turbulence. Analytic approximations are made to simplify the evaluation of certain integrals and series. The method is compared to the more general method of Homicz and George, where practical, and to published experimental data. The agreement between the two theories is excellent. The comparison to the experiments is good although it is not clear how to estimate the increase in intensity of atmospheric turbulence as it is distorted while being drawn into the rotor. The results indicate that atmospheric turbulence is perhaps the major contribution to broadband noise in hover. The approach is also applicable to other load fluctuation mechanisms.

Related Organizations
Keywords

Hydro- and aero-acoustics, Jets and cavities, cavitation, free-streamline theory, water-entry problems, airfoil and hydrofoil theory, sloshing

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selected citations
These citations are derived from selected sources.
This is an alternative to the "Influence" indicator, which also reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Citations provided by BIP!
popularity
This indicator reflects the "current" impact/attention (the "hype") of an article in the research community at large, based on the underlying citation network.
BIP!Popularity provided by BIP!
influence
This indicator reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Influence provided by BIP!
impulse
This indicator reflects the initial momentum of an article directly after its publication, based on the underlying citation network.
BIP!Impulse provided by BIP!
20
Top 10%
Top 10%
Average
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