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OCLC Number: 213811569 Excerpt: ... angle of attack. The straight was installed at the minimum propeller-wing Wing line is drawn through the data for zero droop. A The results in spacing. 18 figure show that the BPF tone level is controlled the propeller angle of by attack and by the presence of the straight wing, but is quite insensitive to the range of droop angles tested, or to small changes in the independent wing angle of attack. The 2xBPF results do show some sensitivity to droop angle the range of in 7 O to of propeller angle of attack, with little effect at angle of 10 " 0 " However, the 2xBPF tone is generally about 20 dB lower than the BPF attack. tone and of little consequence the overall spectrum. in Wins pressures. The two swept wings were fitted with flush-mounted.-pressure sensors as shown In figure The middle sensor was located at the 19. blade tip radius. The sensors were located on the propeller approach side of the wing in each installation, which was on the pressure surface for Inboard-and the suction surface for inboard-down. up, Figure 20 shows the fundamental tone pressure levels measured these by sensors at three angles of attack. At angle of attack the pressure level 0 " is greatest'at the blade tip location indicating wing interaction with the blade tip vortex. However, with increasing angle of attack the pressure dis-tribution stays about the same for the Inboard-down suction surface, but moves inboard for the inboard-up pressure surface, showing tip vortex migration. SUMMARY OF RESULTS A single rotation model turboprop, SR-7A was acoustically tested at simu-NASA lated takeoff / approach conditions Mach ) in the Lewis 9x15 anechoic ( 0.2 in wind tunnel. The propeller was tested with a three tractor configura-wing 30 " up tions ( straight, swept, inboard propeller rotation, and swept, 30 " inboard down propeller rotation ). The propeller was operated at several tip speeds, blade setting angles, and angles of attack. The following sig
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Measured noise of a scale model high speed propeller at simulated takeoff/approach conditions
Bokrecensioner » Measured noise of a scale model high speed propeller at simulated takeoff/approach conditions
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