A parametric study of airframe effects on the noise emission from installed contra-rotating open rotors:

This work reports on the results of the Clean Sky WENEMOR project which has conducted an extensive experimental investigation of installed contra-rotating open rotors on a scale model of an advanced regional aircraft configuration. The tests were conducted in the Pininfarina Wind Tunnel, Italy and the data used for this analysis were taken from a linear far-field array of microphones. The contra-rotating open rotors were operated in pusher and tractor modes with approach and takeoff settings for revolutions per minute and thrust. Realistic modern blade profiles were supplied and utilized through the Clean Sky Green Regional Aircraft program. A range of airframe geometries was tested which included interchangeable tails, engine pylon elongation, engine pylon rotation, and variable wing to engine distance. Changes in the contra-rotating open rotor noise emission to the far field as a function of flow speed, angle of attack, and airframe geometry were clearly identified. The influence of airframe geometry on...