The project pertained to the wind tunnel testing of a common helicopter platform of the heavy-weight class. The aim of the testing activity was the evaluation of the effectiveness (mainly in terms of drag reduction) of the shape optimisation performed by GRC consortium on several components. Both original and optimised models were tested to assess the optimisation effectiveness by comparison.
The tests were complemented by a CFD simulation activity and finally a physical interpretation of the obtained results will be presented.
The first part of the activity of the project was related to the design and production of the model. Although some parts were already existent and have been delivered by GRC2 the model required a completely new internal structure including the rotor hub driving system with the swash plate for the blade pitch control. Thus, the model was designed, manufactured, assembled and instrumented. The dimensioning was based on the load's evaluation coming from the CFD simulations carried out in the frame of this project.
The model could be installed on the wind tunnel pylon in both upside-down and upright mode. The upside-down tests allowed to study the effect of devices laid on the fuselage lower surface (as the vortex generators) avoiding pylon disturbances. On the other hand, the upright tests allowed to evaluate the performance of the helicopter including the rotor-hub (with blade stubs).
Furthermore, the optimized components (vortex generators, gear sponsons, rotor hub caps and blade root fairings) have been completely designed and manufactured.
A comprehensive wind tunnel campaign was performed to assess the aerodynamic effectiveness of CFD-based optimized helicopter components for drag reduction. Several configurations at different angle of attack and sideslip have been tested to assess the performances. Moreover, a purposely designed and developed setup was used to perform several stereo PIV surveys in the region just after the back ramp and in the region just before the fin. The acquired flow fields (as well as the measured steady and unsteady pressures) were quite useful in the physical interpretation of the results.
A CFD activity supported all the design and experimental activity and was particularly important for the evaluation of the wind tunnel effects corrections.