A New Paradigm for Generating Surface-Normal Forces for Hull-Cleaning Robots
Abstract
Barnacles and other forms of marine fouling increase the drag on the submerged surface area of vehicles. This can reduce the speed of a ship by and increase its fuel consumption. This project will develop a proof-of-concept for an autonomous mobile robot, which will be capable of mechanically removing biofouling from a marine vehicle, UUV or weapon. Barnacles and other forms of marine fouling increase the drag on the submerged surface area of ships. This can reduce the speed of a ship by and increase its fuel consumption. With a large fleet of ships and oceangoing vessels, the US Navy spends $1 billion on extra fuel and the cleaning of the hull of its ships. The four fundamentally different approaches to biofouling prevention have been categorized in as (a) physical, (b) chemical, (c) mechanical, and (d) behavioral methods. Physical properties such as surface energy and topography can be potentially engineered for fouling prevention but they have not been proven to be effective. Behavioral methods are impractical as they require the salinity of the water to be changed. Chemical methods are effective but they have a significant negative impact on the environment. Mechanical method, often referred to as grooming, is the best in terms of feasibility and effectiveness and we believe that an autonomous mechanical grooming robot would be a useful item in the Navy s biofouling prevention toolbox. Mechanical grooming can and has been performed by divers but such cleaning operations are difficult and expensive. To eliminate the need for human divers, a hull-?BUG (biomimetic underwater grooming) robot was recently developed by Sea Robotics. The hull-?BUG is approximately 3 feet long, weighs 50 lbs, and uses a simple bulldozer attachment to clean the hull. A spinning propeller inside a cavity on the underside of the hull-?BUG generates a captured vortex to provide surface-? normal force more efficiently than thrusters, allowing it to remain firmly attached to the hull of the ship. This research proposes a different method of generating large surface-?normal forces in a hull-?cleaning robot using a radially outflowing jet. We believe that this method represents a strong potential alternative to both thrusters and the captured vortex. The radial outflow used to hold the vehicle to the hull can also be used to assist the grooming performance. In addition to the large shear stress imposed by the outflow, the fluid stream can be ensonified or combined with a low fraction of blasting media in order to boost the cleaning power of the device. The objective of this research is to develop a proof-?of-?concept for an autonomous mobile robot, which will be capable of mechanically removing biofouling from a marine vehicle. This vehicle will use a novel method for remaining attached to the vehicle, consisting of a radial outflow confined to a thin gap. Basic research, consisting of experiments and simulations, will be used to improve our understanding of this phenomenon so that an optimal set of parameters can be identified for the design.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Nov 23, 2016
- Source ID
- N000141613051
Entities
People
- Ranjan Mukherjee
Organizations
- Michigan State University
- Office of Naval Research
- United States Navy