• DOI:10.2514/6.1992-371
• Corpus ID: 108928831

Far-field noise and internal modes from a ducted propeller at simulated aircraft takeoff conditions

@inproceedings{Woodward1992FarfieldNA,
  title={Far-field noise and internal modes from a ducted propeller at simulated aircraft takeoff conditions},
  author={Richard P. Woodward and Lawrence A. Bock and Laurence J. Heidelberg and David G. Hall},
  year={1992}
}

• R. P. Woodward, L. Bock, +1 author D. G. Hall
• Published 1992
• Engineering, Physics

The ducted propeller offers structural and acoustic benefits typical of conventional turbofan engines while retaining much of the aeroacoustic benefits of the unducted propeller. A model Advanced Ducted Propeller (ADP) was tested in the NASA Lewis Low-Speed Anechoic Wind Tunnel at a simulated takeoff velocity of Mach 0.2. The ADP model was designed and manufactured by the Pratt and Whitney Division of United Technologies. The 16-blade rotor ADP was tested with 22- and 40-vane stators to achieve cut-on and cut-off criterion with respect to propagation of the fundamental rotor-stator interaction tone. Additional test parameters included three inlet lengths, three nozzle sizes, two spinner configurations, and two rotor rub strip configurations. The model was tested over a range of rotor blade setting angles and propeller axis angles-of-attack. Acoustic data were taken with a sideline translating microphone probe and with a unique inlet microphone probe which identified inlet rotating acoustic modes. The beneficial acoustic effects of cut-off were clearly demonstrated. A 5 dB fundamental tone reduction was associated with the long inlet and 40-vane sector, which may relate to inlet duct geometry. The fundamental tone level was essentially unaffected by propeller axis angle-of-attack at rotor speeds of at least 96 percent design.