Investigation of Active Twist Rotor for Blade De-Icing

Abstract

Active twist blades designed by DLR have integrated piezoelectric actuators to twist the blade. The blades are designed to introduce individual blade control (IBC) for helicopter noise and vibration reduction. This paper presents research efforts to investigate the capability of active twist for blade de-icing. Two active twist blades were tested in the Adverse Environment Rotor Test Stand (AERTS) at the Pennsylvania State University, where different icing conditions were adjusted. The electrical input power to the actuators was about 200 Watt for one blade (1.0 m of the blade is active). At temperatures warmer than -17°C, the active twist rotor blade, excited at its first torsional resonance, removed accreted ice of varying stagnation thickness, ranging from 3 mm to 8 mm. These cases were simulated with finite element methods to provide insight into the ice interface stresses and their origin. Based on the finite element simulation a new design for an active twist blade is proposed. The modeled configuration increases the ice interface transverse shear stresses, predicting to shed accreted ice layers with a thickness of less than 2 mm.