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Proceedings Paper

Wind tunnel test of a smart rotor with individual blade twist control
Author(s): Peter C. Chen; Inderjit Chopra
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Paper Abstract

The objective of this research is to develop a smart rotor with active control of blade twist using embedded piezoceramic elements as sensors and actuators to minimize rotor vibrations. A 1/8-th Froude-scale (dynamically-scaled) bearingless helicopter rotor model was built with banks of torsional actuators capable of manipulating blade twist at frequencies from 5 to 100 Hz. To assess the effectiveness of the torsional actuators and vibration suppression capabilities, systematic wind tunnel testing was conducted in the Glenn L. Martin Wind Tunnel. Using accelerometers embedded in the blade tip, the oscillatory blade twist response was measured. The changes in rotor vibratory loads due to piezo- induced twist were determined using a rotating hub balance located at the rotor hub. Experimental test results show that tip twist amplitudes on the order of 0.5 deg are attainable by the current actuator configurations in forward flight. Although these amplitudes were less than the target value (1 - 2 deg for complete vibration suppression control), test results show that partial vibration reduction is possible. Using open-loop phase shift control of blade twist at the first four rotor harmonics, changes in rotor thrust of up to 9% of the steady-state values were measured, resulting in up to 3 and 8% reductions in rotor pitching and rolling moments, respectively. It is expected that the hub load control authority of the smart rotor can be improved in future models with refined actuator configurations and implementation of closed-loop feedback controls.

Paper Details

Date Published: 6 June 1997
PDF: 14 pages
Proc. SPIE 3041, Smart Structures and Materials 1997: Smart Structures and Integrated Systems, (6 June 1997); doi: 10.1117/12.275648
Show Author Affiliations
Peter C. Chen, Systems Planning and Analysis, Inc. (United States)
Inderjit Chopra, Univ. of Maryland/College Park (United States)

Published in SPIE Proceedings Vol. 3041:
Smart Structures and Materials 1997: Smart Structures and Integrated Systems
Mark E. Regelbrugge, Editor(s)

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