Exploitation of active controls and morphing technologies to enhance rotor aerodynamic performance in hover conditions

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Exploitation of active controls and morphing technologies to enhance rotor aerodynamic performance in hover conditions

Garcia-Duffy, Cristina / D'Andrea, Andrea / Melone, Stefano

In the past different rotor morphing concepts and active technologies have been investigated in order to improve helicopter performance. Among them, trailing-edge-deflection (TED), leading-edge-deflection (LED), and active-blade-twist (ABT) have been analyzed with various computational methods in order to demonstrate the capabilities of these concepts to improve vibratory loads, blade-vortex-interaction noise and helicopter performance, especially in forward flight conditions. Power reduction that normally may be obtained by the use of these devices is translated into the capability to diminish fuel level consumption or into the possibility to increase helicopter gross weight or its operative altitude. However, previous studies show virtually no work on assessing the possibility to exploit active and morphing technologies to enhance hovering performance. Hover is often the most critical flight condition as hover maximumgross- weight determines payload and strongly affects range as well as setting the fuel carrying capacity of the aircraft. Hence, the main aim of this paper is to extend the knowledge on this specific field. Different active and morphing technologies are taken into account in this work (variable droop leading edge, active twist and trailing edge flap) in order to highlight the effect of these concepts on helicopter out-of-ground effect hover performance. Results are presented considering each active-morphing technology having different size and actuation deflection magnitude, for different ranges of positions along the span of the blade. Gains in Figure of Merit against thrust levels exhibited by a baseline rotor with the addition of present active technologies, as well as pressure distributions and control loads along the blade span, are examined and reported in the course of this work.