Aeroelasticity and Structural Dynamics
Design and Qualification of Rotating Wing Models
Experimental validation of a flap actuator for helicopter blades
Over the past thirty years, much thought has gone into the improvement of rotary wing aircraft as concerns noise, vibrations, and performance. Due to the major progress that has been made in “intelligent” materials, new concepts like active flaps and active blade torsion are now being studied at Onera. Thus, the objective of Onera/DLR’s “Active Flap Rotor” project is to create a four-blade wind tunnel rotor characterized by an active flap on the trailing edge. A full scale adaptable flap actuator model was made by Onera (figures 1 and 2). It includes a standard actuator based on using prestressed piezoelectric stacks. A device patented by Onera does away with the usual cumbersome bearings with their wear and friction that are incompatible with dynamic operation and the centrifugal field of a blade in rotation. Various tests (including centrifugal tests on Onera’s rotary BRAVoS test stand, see figure 3) were carried out on a prototype flap actuator, to validate the concept and assess its efficiency. The device (control surface and actuator) is being validated today on the model scale (figure 4) for a complete rotor, to validate the simulation codes concerning the acoustic, vibratory and aerodynamic performance of this type of blade.
Fig. 1 – Full scale model flap actuator device built by Onera.
Fig. 2 – Detailed view of the actuator.
Fig. 3 – Rotary BRAVoS test stand.
References
[1] P. Leconte, H-M. des Rochettes, Experimental assessment of an active flap device, AHS 58 th , Annual Forum, Montreal, Canada, June 2002.
[2] H-M. des Rochettes, P. Leconte, J. L. Petitniot, Experimental Assessment and Further Development of Amplified Piezo Actuators for Active Flap Device, Actuator 2002, Bremen, Germany, June 2002.
[3] H. Mainz, B. G. van der Wall (DLR), P. Leconte, F. Ternoy, H-M. des Rochettes (ONERA), ABC Rotor Blades:Design, Manufacturing and Testing, 31th ERF Florence, September 2005
