Industrial measurement campaign on fully equipped helicopter model

Kurzfassung

The flow field around a helicopter is characterised by its inherent complexity including effects of fluid-structure interference, shock-boundary layer interaction, and dynamic stall. Since the advancement of computational fluid dynamics and computing capabilities has led to an increasing demand for experimental validation data, a comprehensive wind tunnel test of a fully equipped and motorized generic medium transport helicopter was conducted in the framework of the GOAHEAD project. In this paper the results of the three-component velocity field measurements are summarized. The effect of the interaction between the main rotor wake and the fuselage for cruise/tail shake conditions was investigated, detecting and analysing the flow characteristics downstream the rotor hub and the rear hatch. The results indicated a sensible increment of the intensity of the vortices shedding form the lower part of the fuselage and a strong influence of the main rotor in the upper region. Furthermore, the pitch up phenomenon was considered, detecting the blade tip vortices impacting on the horizontal tail plane. For high speed forward flight the shock wave forming on the advancing blade was investigated, measuring the location on the blade chord and the intensity. Furthermore, dynamic stall on the retreating main rotor blade in hight-speed forward flight was observed at 40% and 50% blade radius. The analysis of the substructures forming the dynamic stall vortex revealed an unexpected spatial concentration suggesting a rotational stabilization of large scale structures on the blade.