Aeroelasticity and Structural Dynamics
Design and Qualification of Rotating Wing Models
Active helicopter blades
As part of research on future helicopter rotors, the development of active twisting blades is being considered to reduce the radiated noise, improve the aerodynamic performance of the blades, and reduce the vibratory level of the main rotors. In light of current performance of the actuators and large power requirements in the field of shape control, the objective cannot be achieved without changing the usual structure of the blades in depth. A structural concept of a composite blade with active twist, based on a principle patented by Onera, is being studied on the model scale. On this scale, the difficulties are manifold, especially as the prototypes will then have to withstand extreme loads (static and dynamic) that will be applied to them in wind tunnel or centrifugal test stand trials. The actuation principle retained by Onera is based on the use of piezoelectric fiber patches available in the market, and one of the main practical difficulties concerns the isolation of the actuators, supplied at –500/+1500 V. The demonstrator structure (figure 1) was designed with the help of numerical simulation (figure 2), and the simulation results were then compared with the first experimental measurements in the laboratory.
Fig. 1 – Composite demonstrator with active twist
Fig. 2 – Numerical simulation of twist
References
[1] J. Riemenschneider, S. Keye, P. Wierach (DLR), H. Mercier des Rochettes (ONERA), Review of the common DLR/ONERA Project "Active Twist Blade (ATB)", 30 th ERF, Marseille, September 2004.
