Optimization of a Bernoulli Pad for Improving the Efficacy of Shear-Based Grooming of Marine Biofoul
Abstract
Approved for Public ReleaseBarnacles and other forms of marine fouling increase the drag on the submerged surface area of ships. Thi,s can reduce the speed of a ship by 10% and increase its fuel consumption by as much as 40%. With a large fleet of ships and oceango,ing vessels, it is estimated that the US Navy spends $1 billion on extra fuel and the cleaning of the hull of its ships. The four fu,ndamentally different methods to biofouling prevention are: physical, behavioral, chemical, and mechanical. Physical methods have no,t been proven to be effective and behavioral methods are impractical. Chemical methods are effective, but they have a significant ne,gative impact on the environment. Mechanical methods, often referred to as grooming, is the best in terms of feasibility and effecti,veness. Mechanical grooming can be performed by divers, but such cleaning operations are difficult, expensive, and potentially dange,rous. To eliminate the need for human divers, robotic solutions have been proposed; these solutions typically use a method to remain, firmly attached to the hull of the ship and brushes to remove biofouling. Since these brushes can damage the paint of ship hulls, r,esearchers at Michigan State University and the Naval Undersea Warfare Center have been collaborating on developing a method for non,-contact grooming. In this method, a Bernoulli pad is used to create radial outflow between the pad and the biofouled surface. It ha,s been shown that the radial outflow generates both surface-normal and shear forces; the normal forces allow the pad to adhere to th,e hull and the shear forces enable contactless grooming. Experiments conducted over a seven-week period in Narragansett Bay indicate,d that frequent shear-based grooming can restore an Intersleek coated surface to its initial clean state.--Although shear-based groo,ming has shown initial promise, a better understanding of the flow physics is needed to design a Bernoulli pad as an effective devic,efor biofouling mitigation. The nature of the flow precludes an exact solution of the Navier-Stokes equations and therefore this res,earch aims to use computational and experimental investigations to optimize the pad geometry for efficacy. The research will also in,vestigate means by which a pad can be used to clean a large contiguous area through sensing and control. To enable biofouling mitiga,tion of surfaces that are not perfectly planar, this research will investigate pad designs that incorporate flexibility to conform t,o the surface. Basic research, consisting of experiments and simulations, will be used to improve our understanding of radial outflo,w so that an optimal set of parameters can be identified for the design of Bernoulli pads for biofouling mitigation.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Apr 01, 2022
- Source ID
- N000142212143
Entities
People
- Ranjan Mukherjee
Organizations
- Michigan State University
- Office of Naval Research
- United States Navy