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Acoustic characteristics of 1/20-scale model helicopter rotors

Author
Kohlhepp, Fred W.
Published
Aug 1, 1986.
Physical Description
1 electronic document
Additional Creators
Shenoy, Rajarama K. and Leighton, Kenneth P.
Online Version

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Unclassified, Unlimited, Publicly available.
Free-to-read Unrestricted online access
Summary
A wind tunnel test to study the effects of geometric scale on acoustics and to investigate the applicability of very small scale models for the study of acoustic characteristics of helicopter rotors was conducted in the United Technologies Research Center Acoustic Research Tunnel. The results show that the Reynolds number effects significantly alter the Blade-Vortex-Interaction (BVI) Noise characteristics by enhancing the lower frequency content and suppressing the higher frequency content. In the time domain this is observed as an inverted thickness noise impulse rather than the typical positive-negative impulse of BVI noise. At higher advance ratio conditions, in the absence of BVI, the 1/20 scale model acoustic trends with Mach number follow those of larger scale models. However, the 1/20 scale model acoustic trends appear to indicate stall at higher thrust and advance ratio conditions.
Other Subject(s)
Collection
NASA Technical Reports Server (NTRS) Collection.
Note
Document ID: 19880014164.
Accession ID: 88N23548.
NAS 1.26:177355.
NASA-CR-177355.
SER-510248.
Terms of Use and Reproduction
No Copyright.
View MARC record | catkey: 15694726