RCAS Elastic Fuselage Coupling with CFD

Helicopter buffeting is an aeroelastic problem, with mutually interacting airloads and structural motions from the rotor, hub, fuselage, and empennage. Buffeting is amenable to the state-of-the-art analysis technology and addressing it is long overdue. Computational Fluid Dynamics (CFD) provides the highest fidelity for the fluid physics while Computational Structural Dynamics (CSD) provides accurate elastic structure modeling. Combined, CFD/CSD coupled analysis is essential to representing the mutually dependent aeroelastic interactions associated with buffeting. However, current coupling implementations are limited to rotors and wings, while the fuselage and empennage structures critical to the prediction of buffeting are rigidly modeled. An opportunity exists to address this problem by expanding CFD/CSD coupled analysis technology to include the aeroelastic coupling of fuselage and empennage. This effort leverages existing technology for CSD by utilizing the Rotorcraft Comprehensive Analysis System (RCAS) and CFD by utilizing OVERFLOW and Create-AV Helios to focus development on the fluid structure interface (FSI). The main requirements of which are the accurate transfer of deformations to CFD and energy conservation during the application of aerodynamic forces to CSD. Although this development targets interfacing CFD with RCAS, the developed FSI will be general and made available for integration into other structural dynamics programs.