Design and Integration of a Hydroelastic Solver in the Dynamic Model of a Scaled Marine Hydrokinetic Kite

This study presents the framework and initial characterization of a hydroelastic solver for the dynamic model of an underwater marine hydrokinetic (MHK) kite. MHK kites are systems designed to optimally harvest current and tidal energy from bodies of water by executing cross-current flight patterns to augment velocity and therefore power generation. Due to the significant fluid-dynamic loading experienced by MHK kites, robust structural analysis of the kites is integral to successful system design. Hydroelastic analysis allows the coupled hydrodynamic loading and structural deformation of a MHK kite wing to be predicted. The hydroelastic solver outlined here uses a finite-element method to discretize a given wing geometry into a user-selected number of nodes. At each node, hydrodynamic and structural parameters are defined. The hydroelastic solver contains two sub-solvers: (i) a hydrodynamic solver and (ii) an elastic solver. The hydrodynamic solver uses airfoil coefficient lookup tables and Prandtl lifting line theory to estimate lift, drag, and pitching moment at each node across the wing. The elastic solver receives the point loads and moments from the hydrodynamic solver and deforms a defined structural representation of the wing. This hydroelastic solver process is iterated until wing deformation has converged. The integrated model is used to predict the cyclic variation in wing deflection and twist during closed-loop-controlled cross-current flight. Such predictions could prove useful for evaluating hydroelastic effects on optimal kite flight controller tuning, or appropriate design of the kite wing for structural fatigue life considerations.