Open rotor interaction noise reduction through front rotor wake modification

The use of a single optimized bump placed on the leading edge of the front blade of a counter rotating open rotor is envisaged as passive device to reduce the interaction noise at low-speed and high-thrust condition, such as takeoff. This noise reduction device is to be considered as an alternative to rear blade cropping and its penalizing effect on efficiency in cruise condition. The modified front rotor blades provide an acoustic gain that has been linked to the changes on the characteristics of the front rotor wake. The front blade modification has no strong impact on the aerodynamic performance for both takeoff and cruise operating points.