Multi-Objective Optimization for Performance Enhancement of a Toroidal Propeller Using CFD and FSI

Abstract This study aims to optimize the toroidal propeller design to be used for commercial mini-drones. Preliminary CFD simulations were carried out for validation purposes using APC11x5e propeller available in open-source database. In order to validate the numerical results, thrust coefficient, power coefficient, and aerodynamic efficiency obtained from quiescent air and cross-flow-conditions were compared with experimental data. The verified CFD approach showed good agreement with the experimental data for all conditions in obtaining propeller thrust, power, and efficiency values. The same numerical approach was later adopted for the optimization analyses. Optimization was applied to the in-house designed toroidal propeller and was conducted using NSGA-II and Sobol method for DoE combined with FSI. The design variables for multi-objective optimization are the vertical angle, camber angle, and side inclination angle. The aerodynamic objective functions are the thrust and efficiency coefficient and the structural objective function is the strength (von-Mises stress) of the propeller. Ultimately, Pareto optimal designs indicating increased aerodynamic efficiency, higher thrust, and a safer structure are obtained in the defined range of the design variables suggesting that higher thrust, efficiency and strength shall be regarded in the design process of a toroidal propeller for enhanced performance.