Expansion of the prescribed wake code of the rotor simulation program S4 with a CFD-based model of the fuselage-induced velocity

Abstract

An analytical formulation of the induced velocities caused by the HART II helicopter fuselage in the vicinity of the rotor was derived from computational fluid dynamics (CFD) velocity data. The induced velocity model and an analytically integrated displacement of rotor blade tip vortices convecting downstream through this velocity field were implemented into the rotor simulation program S4 of the German Aerospace Center (DLR) in Braunschweig. Tests were conducted showing the model’s influence on the major flow field variables around the rotor disk and the wake trajectory. Comparison with another already implemented fuselage model and an isolated rotor showed that the main flow features were not altered by the HART II model. Still, some changes of flow field variables and vortex trajectories around the rotor plane were found and quantified. The validity of the newly implemented model still has to be confirmed by comparison with experimental data.