A compact underwater vehicle using high-bandwidth coanda-effect valves for low speed precision maneuvering in cluttered environments

A highly maneuver able, compact vehicle for underwater precision inspection of complex structures is presented. The vehicle will have no appendages such as rudders, screws, and other external thrusters, which might get tangled and interfere with the underwater structure in a cluttered environment. A multi-axis, integrated thruster mechanism using Coanda-effect high-speed valves for switching the direction of jets can be encapsulated in a compact, egg-shaped body. Compared to traditional screw thrusters, these valves have improved dynamic performance in switching the jet stream direction. Furthermore, the reaction forces and moments due to switching can be substantially reduced. First, the principle of Coanda effect water jet valves is introduced, and its governing equations are obtained. Optimal dimensions and parameters producing a maximum of thrust are obtained, and are experimentally verified. Multiple Coanda-effect valves are then integrated into a tree structure to create a multi-axis thrust mechanism. A simple planar proof of concept prototype is built and tested.