Development of Rotorcraft Wake Capturing Methodology Using Fully Coupled CFD and Particle Vortex Transport Method

Rotorcraft flow field is extremely difficult to simulate since it is dominated by complex vorticity field generated by the rotor. Traditional Computational Fluid Dynamics (CFD) can predict the generation of these vortices very well but normally cannot handle the evolution of the vortices over a long period of time because of limitations imposed by numerical dissipation and regeneration of grid. The evolution of vortices can be handled satisfactorily using vortex transport method. The present study uses traditional CFD in the vicinity of rotor blades to capture the generation of the vortices, and uses Particle Vortex Transport Method (PVTM) for handling evolution of the vortices into the rest of the flow field. The fully coupled CFD-PVTM is implemented by proper information exchange between the two domains at every time step. The results show that this approach can satisfactorily capture rotor tip vortices as well as the vortex sheet in both hover and high speed forward flight. Comparisons of the blade loads obtained using this fully coupled CFD-PVTM and flight test data show good agreement.