Cruise Noise Measurements of a Scale Model Advanced Ducted Propulsor

TITLE AND SUBTITLE:
Cruise Noise Measurements of a Scale Model Advanced Ducted Propulsor

AUTHOR(S):
James H. Dittmar, Christopher E. Hughes,
Lawrence A. Bock, and David G. Hall

REPORT DATE:
October 1993

FUNDING NUMBERS:
WU-535-03-10

PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES):
National Aeronautics and Space Administration
Lewis Research Center
Cleveland, Ohio 44135-3191

PERFORMING ORGANIZATION REPORT NUMBER:
E-8042

SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES):
National Aeronautics and Space Administration
Washington, D.C. 20546-0001

REPORT TYPE AND DATES COVERED:
Technical Memorandum

SPONSORING/MONITORING AGENCY REPORT NUMBER:
NASA TM-105808
AIAA-93-4400

SUPPLEMENTARY NOTES:
Prepared for the 15th AIAA Aeroacoustics Conference sponsored by the American Institute of Aeronautics and Astronautics, Long Beach, California, October 25-27, 1993. James H. Dittmar and Christopher E. Hughes, NASA Lewis Research Center; Lawrence A. Bock, Pratt & Whitney, United Technologies Incorporated, 400 Main Street, East Hartford, Connecticut 06108; and David G. Hall, Sverdrup Technology, Inc., Lewis Research Center Group, 2001 Aerospace Parkway, Brook Park, Ohio 44142. Responsible person, James H. Dittmar, (216) 433-3921.

ABSTRACT:
A scale model Advanced Ducted Propulsor (ADP) was tested in NASA Lewis Research Center's 8- by 6-Foot Wind Tunnel to obtain acoustic data at cruise conditions. The model, designed and manufactured by Pratt & Whitney Division of United Technologies, was tested with three inlet lengths. The model has 16 rotor blades and 22 stator vanes, which results in a cut-on condition with respect to rotor-stator interaction noise. Comparisons of the noise directivity of the ADP with that of a previously tested high-speed, unducted propeller showed that the ADP peak blade passing tone was about 30 dB below that of the propeller, and therefore, should not present a cabin or enroute noise problem. The maximum blade passing tone first increased with increasing helical tip Mach number, peaked, and then decreased at a higher Mach number. The ADP tests with the shortest inlet showed more noise in the inlet arc than did tests with either of the other two inlet lengths.

SUBJECT TERMS:
Ducted propeller noise; High bypass; Ratio fan noise

NUMBER OF PAGES:
14

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