Can a Conventional Propulsion System Match the Efficiency of an Underwater Glider Buoyancy Engine?

Abstract

AbstractAutonomous underwater gliders are a family of autonomous vehicles used for a long-range, long-term observation of oceanic environments. To do this, they leverage changes in net buoyancy and the resulting vertical motion to generate forward locomotion via hydrodynamic surfaces. To function for extended periods, these systems operate in a low-speed, low-drag regime. Conventionally propelled underwater vehicles typically operate at speeds in excess of those achievable by gliders and therefore require more energy in order to compensate for losses due to hydrodynamic drag. An interesting question arises when considering the operational efficiencies of conventionally propelled systems when they operate at speeds typical of underwater gliders. A first-principles energy-based approach to glider operations was derived and verified using real-world data. The energy usage for buoyancy-driven propulsion was compared to conventional propulsion types. The results from these calculations indicate that a conventionally propelled autonomous underwater vehicle can compete with a buoyancy-driven system given the proper propulsive efficiency.