Aerodynamic Optimization for Rotor Blade with Structural Design in Hover and Forward Flight

Abstract

This study presents an integrated optimization framework for rotor blade design that combines aerodynamic shape optimization and internal structural design within a unified multidisciplinary process. A variable fidelity modeling (VFM) approach is employed to efficiently optimize the blade outer geometry for improved figure of merit (FM) in hover and lift-to-drag ratio (L/Dq) in forward flight. Based on the optimized aerodynamic shapes, internal structural optimization is subsequently performed using a surrogate model for predicting cross-sectional properties, ensuring dynamic feasibility while minimizing blade vibration and weight. Final aeroelastic performance is evaluated through high-fidelity CFD/CSD loose coupling simulations. Optimization results show that individual designs achieve up to 6.5% improvement in FM or up to 6.6% improvement in L/Dq compared to the baseline HART II rotor. Furthermore, cross-validation comparing blades independently optimized by Seoul National University (SNU) and DLR reveals similar aerodynamic trends and performance, demonstrating the robustness and general applicability of the proposed framework across different simulation setups.