Evolution of Active Twist Rotor Designs at DLR

Abstract

Unsteady flow conditions in the rotor disk are causing intense vibrations and noise in rotary wing aircrafts. Even modern helicopters still suffer from these drawbacks. This decreases the on board comfort, causes material fatigue and reduces the public acceptance of helicopters. For this reason there are many affords towards an active manipulation of the flow conditions to decrease noise and vibrations. This could also lead to a reduction of fuel consumption. One of the most promising approaches to do so is a secondary control by deformation of the individual blades. Such an actuation can be realized by the integration of piezoelectric actuators in the blade itself, which causes the blade to twist. The German Aerospace Center (DLR) started to work with active twist rotor blades in the early 90. Ever since, the technology of actuation has evolved drastically, opening new ways to twist blades by means of actuators. This paper presents the evolution of blade design in the last years.