Computations of Flapping Flow Propulsion for UUV Design

Three-dimensional unsteady computations of the flow past a flapping and deforming fin are performed. The computed unsteady lift and thrust force time histories are validated with experimental data and are in good agreement. Several fin parametric studies are performed for a notional Unmanned Underwater Vehicle (UUV). The parametric studies investigated the force production of the fin as a function of varying the flexibility, the bulk amplitude of fin rotation, the vehicle speed and the fin stroke bias angle. The results of these simulations are used to evaluate the hydrodynamic performance of the vehicle and to support controller development. Computations are also performed to map out the hydrodynamic characteristics of a new test vehicle, designed and built at NRL to demonstrate the hovering and low-speed maneuvering performance of a set of actively controlled curvature fins.