Advances in tilt rotor noise predictionThe two most serious tilt rotor external noise problems, hover noise and blade-vortex interaction noise, are studied. The results of flow visualization and inflow velocity measurements document a complex, recirculating highly unsteady and turbulent flow due to the rotor-wing-body interactions characteristic of tilt rotors. The wing under the rotor is found to obstruct the inflow, causing a deficit in the inflow velocities over the inboard region of the rotor. Discrete frequency harmonic thickness and loading noise mechanisms in hover are examined by first modeling tilt rotor hover aerodynamics and then applying various noise prediction methods using the WOPWOP code. The analysis indicates that the partial ground plane created by the wing below the rotor results in a primary sound source for hover.
Document ID
19930035187
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
George, A. R. (NASA Ames Research Center Moffett Field, CA, United States)
Coffen, C. D. (NASA Ames Research Center Moffett Field, CA, United States)
Ringler, T. D. (Cornell Univ. Ithaca, NY, United States)