Prediction of Hover Validation and Acoustic Baseline Hovering Rotor Performance and Ground Effect Using Mercury Framework

Simulations of the Hover Validation and Acoustic Baseline rotor in the hovering state were conducted using the Mercury framework, a multimesh, heterogeneous CPU-GPU overset computational fluid dynamics framework. Isolated hovering rotor simulations were conducted, and efficiency parameters were compared with the available reference data for various collective pitch angles. For installed rotor simulations, the NASA ROBIN-Mod7 fuselage was used. The sectional thrust of the blade increased when passing over the nose and tail boom of the fuselage owing to the ground effect, whereas the fuselage download decreased the total lift. The hover-in-ground effect was investigated for the rotor–fuselage configuration at various rotor heights from the ground. The ground effect increased as it approached the ground, thereby increasing the rotor figure of merit and decreasing fuselage download. The sectional thrust of the blade increased under the ground effect, except near the tip. Otherwise, the sectional torque was not significantly affected. Finally, the groundwash velocity was computed for an installed rotor at a collective of [Formula: see text]. Owing to the highly unsteady flow features, the results were phase- or time-averaged. The ground velocity profiles at various azimuthal and radial locations were compared to study the effects of rotor height, fuselage existence, and ground-wall boundary conditions.