Semi-Empirical Physics-Based Modeling of Fuselage-Rotor and Fuselage-Wake Interferences for Comprehensive Codes

A semi-empirical analytical formulation of the induced velocities generated by the fuselage shell of the HART II wind tunnel model in the volume around the rotor is derived from computational fluid dynamics velocity data. The operational conditions investigated range from vertical descent, shallow descent, level flight and climb to vertical ascent and from forward to quartering flight. The analytical induced velocity model can directly be used to account for the inflow at the blade elements and also allows for analytical or numerical integration of rotor wake convection to compute the associated displacements of rotor blade tip vortices travelling downstream within this velocity field. The model's influence on the major flow field variables around the rotor disk and the wake trajectory is demonstrated. Since the method is generic it is anticipated that the effect of any kind of fuselage can be accounted for this way and it may be used within any comprehensive code for blade element aerodynamics, within prescribed wake codes and even free-wake codes for influencing the wake convection.