|
Advances in Aircraft and Spacecraft Science Volume 1, Number 1, January 2014 , pages 69-91 DOI: https://doi.org/10.12989/aas.2014.1.1.069 |
||
|
An active back-flow flap for a helicopter rotor blade |
||
Steffen Opitz,Kurt Kaufmann and Anthony Gardner
|
||
| Abstract | ||
| Numerical investigations are presented, which show that a back-flow flap can improve the dynamic stall characteristics of oscillating airfoils. The flap was able to weaken the stall vortex and therefore to reduce the peak in the pitching moment. This paper gives a brief insight into the method of function of a back-flow flap. Initial wind tunnel experiments were performed to define the structural requirements for a detailed experimental wind tunnel characterization. A structural integration concept and two different actuation mechanisms of a back-flow flap for a helicopter rotor blade are presented. First a piezoelectric actuation system was investigated, but the analytical model to estimate the performance showed that the displacement generated is too low to enable reliable operation. The seond actuation mechanism is based on magnetic forces to generate an impulse that initiates the opening of the flap. A concept based on two permanent magnets is further detailed and characterized, and this mechanism is shown to generate sufficient impulse for reliable operation in the wind tunnel. | ||
| Key Words | ||
| back-flow flap; active flap; flow control; solid state hinge; helicopter; rotor blade | ||
| Address | ||
| Steffen Opitz: German Aerospace Center (DLR), Institute of Composite Structures and Adaptive Systems, Lilienthalplatz, 7, 38108 Braunschweig, Germany Kurt Kaufmann and Anthony Gardner: German Aerospace Center (DLR), Institute of Aerodynamics and Flow Technology, Bunsenstra | ||
