NASA Technical Reports Server (NTRS) : Acoustic pdf

NASA Technical Reports Server (NTRS) : Acoustic

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Description of the Book:

The augmentor wing concept is being studied as one means of attaining short takeoff and landing (STOL) performance in turbofan powered aircraft. Because of the stringent noise requirements for STOL operation, the acoustics of the augmentor wing are undergoing extensive research. The results of a wind tunnel investigation of a large-scale swept augmentor model at forward speed are presented. The augmentor was not acoustically treated, although the compressor supplying the high pressure primary air was treated to allow the measurement of only the augmentor noise. Installing the augmentor flap and shroud on the slot primary nozzle caused the acoustic dependence on jet velocity to change from eighth power to sixth power. Deflecting the augmentor at constant power increased the perceived noise level in the forward quadrant. The effect of airspeed was small. A small aft shift in perceived noise directivity was experienced with no significant change in sound power.

Sealing the lower augmentor slot at a flap deflection of 70 deg reduced the perceived noise level in the aft quadrant. The seal prevented noise from propagating through the slot

• Creator/s: NASA Technical Reports Server (NTRS
• Date: 11/1/1973
• Year: 1973
• Book Topics/Themes: NASA Technical Reports Server (NTRS), ACOUSTIC PROPERTIES, ENGINE NOISE, LIFT AUGMENTATION, SHORT TAKEOFF AIRCRAFT, TURBOFAN ENGINES, ACOUSTIC MEASUREMENT, AERODYNAMIC CHARACTERISTICS, NOZZLE FLOW, Falarski, M. D., Koenig, D. G

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