Preliminary design of a scaled rotor blade with vibration and noise control devices
In this paper, the preliminary design and manufacture of the SHARCS (Smart Hybrid Active Rotor Control System) scaled rotor blade and its accompanying control systems are presented. The primary objective of this research is the simultaneous reduction of noise and vibration generated by a rotor blade. The simultaneous noise and vibration control is achieved using three active control systems. Wind tunnel tests will be implemented to evaluate the design and demonstrate that the combination of the control systems can reduce both vibrations and noise. The control systems are an Actively Controlled Flap (ACF), an Actively Controlled Tip (ACT) and an Active Impedance Control device (AIC also known as Smart Spring) that replaces the pitch link. The designed flap control system uses piezoelectric actuators and can deflect 4 degrees at a 3 per rev frequency. The anhedral tip is electric motor driven and deflects 20 degrees over a few seconds. Finally, the smart spring is to control the blade vibration by modifying its boundary conditions at the root. Using close Mach and Lock numbers as well as given natural frequencies of vibration, the SHARCS rotor was scaled in a manner so that aeroacoustic and aeroelastic similarities were maintained with a full-scale rotor blade. After a try on NACA 0012, the blade section NACA 0015 was chosen to accommodate the control systems. The symmetric geometry of this blade section and the symmetric lay-up of the composite laminates, help in preventing out of plane strains, and the coupling of bending and stretching in the composite blade that can result in warping due to the applied centrifugal load. The composite lay-up of the articulated blade was iterated and tested by finite elements method (FEM) so that the natural frequencies match the required ones closely. The final check point in blade design is stress and failure mode analysis that is currently under way.
|Keywords||Active control, Blade vortex interaction (BVI), Noise, Smart rotor, Smart spring, Vibration|
|Conference||National Aerospace Laboratory NLR - 32nd European Rotorcraft Forum, ERF 2006|
Ghorashi, M. (M.), Mikjaniec, T. (T.), Lynch, B. (B.), Ulker, F.D. (F. D.), Cha, M. (M.), Mander, A. (A.), … Nitzsche, F. (2007). Preliminary design of a scaled rotor blade with vibration and noise control devices. In National Aerospace Laboratory NLR - 32nd European Rotorcraft Forum, ERF 2006 (pp. 335–349).