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Predicted and measured boundary layer refraction for advanced turboprop propeller noiseCurrently, boundary layer refraction presents a limitation to the measurement of forward arc propeller noise measured on an acoustic plate in the NASA Lewis 8- by 6-Foot Supersonic Wind Tunnel. The use of a validated boundary layer refraction model to adjust the data could remove this limitation. An existing boundary layer refraction model is used to predict the refraction for cases where boundary layer refraction was measured. In general, the model exhibits the same qualitative behavior as the measured refraction. However, the prediction method does not show quantitative agreement with the data. In general, it overpredicts the amount of refraction for the far forward angles at axial Mach number of 0.85 and 0.80 and underpredicts the refraction at axial Mach numbers of 0.75 and 0.70. A more complete propeller source description is suggested as a way to improve the prediction method.
Document ID
19900008097
Acquisition Source
Legacy CDMS
Document Type
Technical Memorandum (TM)
Authors
Dittmar, James H.
(NASA Lewis Research Center Cleveland, OH, United States)
Krejsa, Eugene A.
(NASA Lewis Research Center Cleveland, OH, United States)
Date Acquired
September 6, 2013
Publication Date
January 1, 1990
Subject Category
Acoustics
Report/Patent Number
NAS 1.15:102365
NASA-TM-102365
E-5081
Accession Number
90N17413
Funding Number(s)
PROJECT: RTOP 535-03-01
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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