A High-Fidelity Coupled CFD–CSD Framework for Articulated Rotorcraft Analysis

This study presents a high-fidelity fluid–structure interaction framework aimed at capturing unsteady aerodynamic phenomena in articulated helicopter rotors. The aerodynamic solver is capable of efficient yet physically consistent representation of rotating blades within a compressible CFD framework. This approach resolves key flow features such as blade–vortex interaction, wake contraction and deformation, rotor–fuselage interference, and large-scale unsteady flow separation without requiring body-fitted blade meshes. The structural response of the rotor blades is modeled and coupled in a time-accurate manner with the flow solver. The structural model complements the aerodynamic simulation by providing realistic blade motion under aerodynamic loading, enabling the analysis of aeroelastic effects and active control responses. To assess the impact of active control on the flow field, Higher Harmonic Control inputs are prescribed as harmonic variations in blade pitch. The coupled framework is used to examine how these inputs modify vortex shedding patterns, tip vortex trajectories, and overall wake structure. The simulations show reduction in hub vibratory loads, accompanied by changes in wake structure and vortex behavior under various control inputs. This coupled CFD-CSD framework enables detailed investigation of flow–structure coupling in rotorcraft configurations, with particular attention to flow control, and the impact of blade motion on aerodynamic field evolution.