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Noise Survey of a 10-foot Four-blade Turbine-driven Propeller Under Static Condtions

出版	National Advisory Committee for Aeronautics, 1955
URL	http://books.google.com.hk/books?id=Vc1CAQAAIAAJ&hl=&source=gbs_api
EBook	FULL_PUBLIC_DOMAIN

註釋Overall sound-level measurements and frequency analyses of tape recordings of the noise emitted from a 10-foot-diameter, four-blade propeller mounted on a turbine-powered vehicle have been made under static conditions at stations equally spaced on a 75-foot-radius circle. The overall propller-noise pattern was unsymmetrical about the fuselage center line, the maxtium sound-pressure level being located in the right rear quadrant. The frequency analysis shows that this unsymmetrical distribution consists primarily of the two lowest propeller harmonics. In the plane of and ahead of the propeller, harmonics as high as the eleventh are important.