High-fidelity multi-level efficiency optimization of propeller for high altitude long endurance UAV

This paper describes the development of a high-fidelity multi-level optimization framework to maximize the efficiency of a propeller. Specifically, the discrete adjoint method optimizes the airfoil cluster in a three-dimensional state. Subsequently, parametric perturbation and flow pattern reconstruction methods are applied to the optimization of the twist angle and chord length distribution. Additionally, we use the concepts of perturbation loss and additional efficiency to quantify the influence of the viscosity loss on the efficiency and the potential chord length optimization at each blade section. The precision during the optimization is consistent with that of Computational Fluid Dynamics (CFD), which agrees well with the experimental data. The results indicate that the proposed optimization framework can efficiently combine high fidelity and low computational costs and accurately quantify the influence of complex three-dimensional flow characteristics on the optimal shape of the propeller. With the aid of the proposed optimization criterion, the three-dimensional flow can reach the state that is most conducive to improving the propeller efficiency by adjusting the shape parameters. Overall, this research's methodology and general rules provide a reference for the propeller design of a high altitude long endurance UAV.