Autonomous Underwater Vehicle (AUV) Propulsion System Analysis and Optimization

One of the largest design considerations for autonomous underwater vehicles (AUV's) that have specific mission scenarios is the propulsive efficiency. The propulsive efficiency affects the amount of power storage required to achieve a specific mission. As the efficiency increases the volume of energy being stored decreases. The decrease in volume allows for a smaller vehicle, which results in a vehicle that requires less thrust to attain a specific speed.

The process of selecting an efficient propulsive system becomes an iterative process between motor, propeller, and battery storage. Optimized propulsion systems for mission specific AUV's require costly motor and propeller fabrication which may not be available to the designer. Recent advancements in commercially available electric motors and propellers allows for cost effective propulsion systems. The design space selection of motors and propellers has recently increased due to component demand of remote control airplane and boats. The issue with such systems is how to predict small propeller and small motor performance interactions since remote control motor and propeller designers usually don't provide enough information about the performance of their product.

The mission statement is to design a propeller and motor combination that will allow an autonomous underwater vehicle to travel large distances while maintaining good efficiency. The vehicle will require 12 N of thrust with a forward velocity of 2 m/s. The propeller needs to be larger than 2.5â due to inflow velocity interaction and smaller than 4â due to loss of thrust when in surface transit due to suction.