A Viscous Vortex Particle Model for Rotor Wake and Interference Analysis

This paper presents a viscous vortex particle model that was developed to address the challenging rotor wake and interference problems. The viscous vortex particle modeling technology can accurately solve the complicated rotor wake variation and is well suited for aerodynamic interaction simulation in complex environments. The current model directly solves the velocity-vorticity form of the incompressible Navier-Stokes equation using a grid-free Lagrangian simulation, which overcomes the hurdle of artificial numerical dissipation inherent in most current grid-based Navier-Stokes CM methods and provides a successful solution to the rotor vorticity transportation and interaction. This paper discusses the fundamental formulation, the numerical algorithms, and the simulation results. The rotor wake geometry and downwash were investigated for different rotor configurations operating in hover, forward flight, in ground effect, and in a shipboard environment, including comparisons with the available measured data. Excellent agreement was obtained. The model was also used to trim a full UH-60 rotorcraft in level flight, and encouraging results were obtained.