Identification of rotor wake inflow finite-state models for flight dynamics simulations

Abstract

The aim of this work is the development of dynamic, finite-state modelling of wake inflow generated by kinematic perturbations of rotors in steady flight conditions. Extracted from responses of high-fidelity aerodynamic solvers, it is suited for flight dynamics applications. A three-step identification procedure is proposed: (1) evaluation by a high-fidelity solver of the wake inflow due to harmonic perturbations of rotor kinematics, (2) determination of the corresponding inflow coefficient transfer functions, and (3) rational approximation of the transfer functions. Wake inflow models related to rotor loads (like the well-known Pitt–Peters model) are obtained, as well, as by-products of that proposed. Considering aerodynamic simulations provided by a solver based on a boundary element method for potential flows, the numerical investigation presents the validation of the proposed finite-state wake inflow modelling, along with the examination of identified models related to rotor loads, for a rotor in steady flight conditions subject to arbitrary perturbations.