Flow field characterization and interactional aerodynamics analysis of a complete helicopter

The flow field around a helicopter is characterized 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 size transport helicopter was conducted in the framework of the GOAHEAD project.In this paper the test campaign results in terms of three-component velocity field and fluid–structure interaction are discussed. The effect of the interaction between the main rotor wake and the fuselage for cruise/tail shake conditions is investigated, analyzing the flow characteristics downstream the rotor hub and the rear hatch for the case of isolated fuselage and full equipped model. The results indicate 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.The rotor/fuselage interaction is further discussed mainly taking into account the static and dynamic loads and the static and dynamic pressure distributions measured on the fuselage model.Furthermore, the pitch-up phenomenon is considered by detecting the blade tip vortices impacting on the horizontal tail plane, and by measuring the effects on the horizontal tail plane in terms of vertical loads, pressure distribution and integral sectional forces and finally the effect on the full fuselage loads. For high-speed forward flight, the shock wave forming on the advancing blade is investigated by measuring its intensity and the location on the blade chord.