Analytical methods for modeling inflow dynamics of a co-axial rotor system

The finite-state dynamic wake modeling has proven to be a convenient and efficient framework to model rotor inflow for flight mechanic simulations. Recent developments in the finite-state inflow modeling have advanced the state of the art with closed-form solution for all three components of the flow everywhere in the flow field [1]. However, a direct extension of the single rotor inflow models to a co-axial rotor configuration introduces significant challenges. This paper presents two competing methods, one based on superposition of velocity potentials of individual rotors and the second one based on superposition of pressure potentials of individual rotors. The models obtained using the two competing approaches are compared in terms of their compatibility for real time implementation, computational efficiency and model simplifications. Also, representative simulation results from the two competing models are presented and compared.