Skin-Friction Predictions on a Hovering Tilt-Rotor Blade

摘要

Skin-friction predictions on hovering XV-15 helicopter blades have been made with the OVERFLOW2 flow solver using the Spalart-AIImaras one-equation turbulence model. The figure of merit for the 10 deg collective pitch is predicted reasonably, and for the 3 deg collective pitch it is underpredicted in comparison with experimental data. The trend in the skin-friction predictions at the 10 deg collective pitch in the fully turbulent region is in good agreement with the experimental data at radial stations away from the hub. For the 3 deg collective pitch, the agreement in the fully turbulent region is not as good as for the 10 deg case. In the transition region, the predictions deviate significantly from the experimental data for both the cases. By modulating the turbulence viscosity a priori in the experimentally known transition zone in various ways, a measurable change was predicted in the behavior of skin friction over the blade. This change was observed to be significant for the 3 deg collective pitch. Skin-friction results corresponding to the fully laminar calculations are in good agreement with experimental skin friction in the laminar region for both of the collective pitch angles.