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Simulation of flight-type engine fan noise in the NASA-Lewis 9 x 15 anechoic wind tunnelA major problem in the measurement of aircraft engine fan noise is the difficulty of simulating, in a ground-based facility, the noise that occurs during flight. Flight-type noise as contrasted to the usual ground-static test noise exhibits substantial reductions in both (1) the time unsteadiness of tone noise and (2) the mean level of tones calculated to be nonpropagating or cut-off. A model fan designed with cut-off of the fundamental tone was acoustically tested in the anechoic wind tunnel under both static and tunnel flow conditions. The properties that characterize flight-type noise were progressively simulated with increasing tunnel flow. The distinctly lobed directivity pattern of propagating rotor/stator interaction modes was also observed. The results imply that the excess noise attributed to the ingestion of the flow disturbances that prevail near most static test facilities was substantially reduced with tunnel flow. The anechoic wind tunnel appears to be a useful facility for applied research on aircraft engine fan noise under conditions of simulated flight.
Document ID
19770061604
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Heidmann, M. F.
(NASA Lewis Research Center Cleveland, OH, United States)
Dietrich, D. A.
(NASA Lewis Research Center Cleveland, Ohio, United States)
Date Acquired
August 9, 2013
Publication Date
November 1, 1976
Subject Category
Aircraft Propulsion And Power
Meeting Information
Meeting: Meeting of the Acoustical Society of America
Location: San Diego, CA
Start Date: November 16, 1976
End Date: November 19, 1976
Sponsors: Acoustical Society of America
Accession Number
77A44456
Distribution Limits
Public
Copyright
Other

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