Development of a Rotor Test Facility for the Investigation of Dynamic Stall

The flight envelope of modern helicopters is limited due to unsteady flow phenomena such as dynamic stall. Most investigations regarding this topic, both experimental and numerical, were done on pitching two-dimensional airfoils. Therefore, it is of great interest to investigate the dynamic stall on rotating blades in order to get a better understanding of the unsteady aerodynamics and to improve future rotor designs. A rotor test facility is being built at the DLR in Göttingen. The test rig is integrated into an existing wind tunnel facility and the surrounding conditions were defined. Critical load cases were derived from numerical flow simulations of the rotor blade, and a finite element analysis including a fatigue analysis was performed. A telemetry system is integrated into the rotor head and unsteady pressure sensors are installed in the rotor blades. The development process with its validation and the design of the rotor head and blades are described in this paper.