Identification of the Origins of Blade-Vortex Interaction (BVI) Noise in Helicopters

One of the leading concerns regarding the commercial and military applications of rotary wing powered vehicles is the issue of blade-vortex interaction (BVI) noise occurring during forward descent. This impulsive noise-generating phenomenon occurs due to the close proximity and interference between the main rotor blades and the wake vortices generated by the rotor blades from previous revolutions. Throughout the descent phase of a helicopter in forward flight, the rotating blades pass through these induced vortices, thus generating an impulsive "slap" noise that is characteristic of the common sound associated with helicopter flight among the general population. Therefore, parameterization of the variables of interest that affect BVI noise generation will allow for thorough analysis of the origins of the noise and open pathways for innovation that may offer significant improvements in acoustic performance. Gaining an understanding of the factors that govern the intensity of the BVI acoustic signature provides a strong analytical and experimental basis for enhanced rotor blade design.