Installation effects on contra-rotating open rotor noise

*† ‡ § ** †† The investigation of Contra-Rotating Open Rotor (CROR) installation effect has been updated with an extensive wind tunnel test at DNW LLF using a 1/6th scale CROR rig and several engine pylon mock-ups mounted upstream of the propellers. Experimental observations allow the characterization of the pylon-rotor interaction phenomena in terms of the spectral contents, polar and azimuthal directivities, sensitivities to pylon design and positioning, and sensitivities to the propeller working conditions. The pylon was equipped with trailing edge blowing system that was shown to be very efficient to reduce the pylonrotor interaction noise.