Helicopter Blade-Vortex Interaction Noise Suppression

Sponsored by: NASA/Langley Research Center
Team Members: AITHER, University of Maryland, College Park, Morgan Matroc

With increasingly stringent noise pollution controls and public opinion against loud and obtrusive helicopter noise, many efforts are underway to lessen all forms of helicopter noise. Blade-Vortex Interaction (BVI) noise is one of the most challenging noise sources facing helicopters today. BVI occurs when a rotor blade strikes the vortex created by the tip of the preceding blade. The most direct method of reducing this effect is by ensuring that the two do not cross by changing the plane of the striking blade.

One potential approach is to incorporate smart piezoelectric actuators within the blade itself to control its position. Along these lines, AITHER designed a Mach-scaled smart helicopter rotor with active blade twist control capability. Embedded piezoelectric actuators provide integral blade twist control of the rotor.

During this effort, a feasibility study was completed that accomplished the following milestones: (1) verified the viability of using embedded piezoceramics for BVI noise control, (2) examined the performance capabilities of candidate twist actuation technologies, (3) developed a simplified baseline model of isolated blade with oblique and parallel vortex interactions, and (4) quantified expected active noise reduction with distributed twist control.