Computational Study of Helicopter Rotor-Fuselage Aerodynamic Interactions

Aerodynamic interactions between the main rotor, fuselage, and tail rotor must be considered during the design phase of a helicopter, and their effect on performance must be quantified. However, interactional helicopter aerodynamics has so far been considered by very few researchers. In this work, the Helicopter Multi-Block flow solver is used to investigate the flow around two generic rotor-fuselage cases before moving on to a more realistic full-helicopter geometry under investigation in the European Commission Framework 6 Generation of Advanced Helicopter Experimental Aerodynamic Database project. A comparison of the computational fluid dynamics results obtained with experimental data shows that the method is capable of resolving the main interactional flow features for the generic cases. A similar comparison with experimental data for the Generation of Advanced Helicopter Experimental Aerodynamic Database test case has not yet been conducted, but the obtained results show that even for a test case of high complexity, state-of-the-art rotorcraft computational fluid dynamics methods are capable of providing realistic predictions. However, comparisons with isolated rotor cases clearly show the increased loading as the blade passes over the nose of the helicopter as the result of a fuselage-induced upwash. Similarly, the fuselage induces a reduction of the blade loading for inboard stations when the blades passes through the rear part of the rotor disk. The present results highlight and quantify the radial and azimuthal extent of the rotor-fuselage interactional effect on the rotor loading.