Propeller–motor-coupled modeling and design for tiltrotor aircraft

Purpose This study aims to propose a rapid optimization design framework for the electric propulsion system of tiltrotor aircraft with a comprehensive set of propeller and motor parameters. Design/methodology/approach To enhance the prediction accuracy, the authors have developed correction models for both the propeller and motor, i.e. the propeller performance model is based on blade element momentum theory, with the Reynolds-averaged Navier–Stokes method to obtain blade airfoil aerodynamic data, and the motor performance model incorporates an experimentally corrected second-order equivalent circuit model. Using Bayesian optimization algorithms, the authors have addressed the mixed-integer nonlinear programming design problem, which includes discrete variables such as the number of propeller blades and blade airfoil type, as well as continuous variables such as propeller diameter, pitch angle, chord length distribution, twist angle distribution, initial motor resistance, no-load current and KV value. Findings To estimate the aircraft-level performance, the authors have integrated the electric propulsion system into the tiltrotor’s overall mission profile, where an energy consumption reduction of 34.1% for the mission profile can be achieved after propeller and motor simultaneous optimization. Originality/value This study provides a valuable tool for the preliminary design and optimization of the electric propulsion systems for tiltrotor aircraft.