Real-Time Simulation of Coaxial Rotor Configurations with Combined Finite State Dynamic Wake and VPM

This paper describes a first-principle based finite state dynamic rotor wake model that addresses the complex aerodynamic interference inherent to coaxial rotor configurations in support of advanced vertical lift aircraft simulation, design, and analysis. The high fidelity rotor dynamic wake solution combines an enhanced real-time finite state dynamic wake model (DYW) with a first-principle based viscous Vortex Particle Method (VPM). The finite state dynamic wake model provides a state-space real-time modeling capability for advanced rotorcraft configurations and VPM provides a first-principle based solution for the complex rotor wake problem without using ad-hoc parameters. To account for the mutual aerodynamic interference between multiple rotors, the finite state dynamic wake model was enhanced with several essential modeling parameters to empirically account for important physical phenomena. These modeling parameters were determined based on high fidelity VPM simulations. The developed methodology provides a first-principle based real-time finite state dynamic wake model suitable for coaxial rotor configurations. To validate the developed model, simulation results for the rotor performance, the rotor wake dynamics, and the flow field of different coaxial rotor configurations in both hover and forward flight conditions were compared with available measured data. The simulation results demonstrate good correlation with the measurements for all the cases evaluated.