CFD DRAG AND POWER PREDICTION FOR A ROTOR IN HOVER OR FORWARD FLIGHT - FORMULATION AND FIRST APPLICATIONS

Two general formulations based on the momentum equations are developed in this paper, They both aim at predicting the power consumed by a ro tor from a given field solution. The first formulation concerns forwar d night configurations for which the inviscid flow-field around the bl ades is calculated using the 3D unsteady Full Potential equations and the second one concerns hover configurations modeled using a 3D Euler solver. In each case, the computational method can be coupled to a 3D laminar-turbulent boundary layer code in order to have access to the v iscous drag. The theoretical aspects are first validated, then applied to non-lifting as well as lifting configurations. Results in forward flight present a reasonable agreement with experiment (for the torque prediction). In hover, the database used for the comparisons did not i nclude values for the power consumed by the rotor. This study shows th at drag and power predictions with the use of CFD methods for helicopt er configurations is not unrealistic and can bring a better understand ing of the drag production mechanisms.