Navier-Stokes prediction of helicopter rotor performance in hover including aeroelastic effects

Two numerical methods (the DLR code FLOWer and the ONERA code CANARI), based on the resolution of the Reynolds Averaged Navier-Stokes equations, are applied in this paper in order to compute the performance of helicopter rotors in hover. The comparison of computed performance with experimental results of the scale-1 BO-105 rotor and the model 7A rotor assuming rigid blades shows a significant overestimation of rotor thrust and power. An easy and efficient way to account for the blade elasticity in torsion is then described. The new aeroelastic computations show much better agreement with experiment, especially for the hingeless BO-105 rotor, even if the figures of merit are underestimated for a given thrust coefficient. It is finally shown that accounting for a laminar-turbulent boundary layer (instead of a fully turbulent boundary layer) in the Navier-Stokes code significantly increases the estimated figure of merits thus improving the correlation between computations and experiment.