Exploration of a 3-D Fluid-Structure Interface for Mis-matched RANS-FEA Meshes of a Helicopter Rotor

This paper develops and demonstrates a three-dimensional patch force based fluid-structure interface to predict the dynamic stresses and strains on helicopter rotor blades. The demonstration is limited to ideal hover. The interface is used to analyze a full-scale hingeless rotor configuration with fluid and structural meshes developed from a common CAD geometry. A gradient extrapolation method is used to calculate virtual work across mismatched mesh boundaries. Hover airloads are calculated at a fixed collective using the U.S. Army CREATE™-AV Helios RANS solver and imposed on the University of Maryland X3D three-dimensional finite element solver. Stresses are computed and compared between the new patch force interface and the conventional sectional airloads interface. Because blade deformations are steady in hover and dominated by centrifugal loading, the stresses are generally similar, with differences of up to 20%.