A Hydrodynamic Analysis and Conceptual Design Study for an External Storage Enclosure System for Unmanned Underwater Vehicles.

Abstract

Medium-sized Unmanned Underwater Vehicles (UUV) are limited in their scope of operations, range, and endurance by their relatively small energy storage capacity. The majority of commercially available medium-sized UUVs are incapable of mission operations with durations longer than 30 hours, many unable to achieve 24 hours. The complex integration of control and instrumentation equipment internal to the UUV has a detrimental impact on the location, type and number of sensors installed within UUVs of this size, and are often at the cost of additional energy storage capabilities. This research investigates the hydrodynamic resistance and powering requirements needed to support a conceptually designed rigid multi-bodied UUV built around DARPA’s SUBOFF hull from, the goal being to develop new and innovative low-cost methods of modifying commercially available UUVs to enhance range, payload capabilities and sensory performance through the use of novel external enclosure systems. This thesis investigates the impact on the UUV’s drag by optimizing the location and size of the spheroidal shaped external mounted equipment bays such that resistance is minimized. Enclosures are capable of extending the sensor and payload capacity or increasing the onboard energy storage via detachable store pods. Energy storage methods, total energy capacity, and the impact of the overall system on range are investigated utilizing the constrained weight and volume of a 3000-meter-deep capable pressure hull. Performance is predicted via Computational Fluid Dynamics using OpenFOAM and is validated using Experimental Fluid Dynamics via model towing resistance. Structural strength was determined by Finite Element Analysis.