Instrumented Test Facility for Underwater Robotics
Abstract
ABSTRACT:Barnacles and other forms of marine fouling increase the drag on ships. This can reduce the speed of a ship and signi#cantly increase its fuel consumption. With a large #eet of ships, the US Navy is forced to spend $1 billion on extra fuel and the cleaning of the hull of its ships. With funding from ONR, the principal investigator is developing a robotic device for biofouling mitigation. The device will use a Bernoulli pad to create suction to adhere to the ship hull; the shear forces generated by the radial out#ow between the pad and hull will remove fouling. The e#ectiveness of the Bernoulli pad based biofouling mitigation device will depend on its ability to generate su#ciently large shear and suction forces; this will require optimization of the Bernoulli pad parameters. Simulations and experiments will be used to also investigate the e#ectiveness of the device on curved surfaces and surfaces with rivets that are characteristic of ship hulls. The design of the optimal pad will require extensive computational #uid dynamics (CFD) simulations together with carefully designed experiments that can provide critical measurements for improv-ing the accuracy of the simulations as well as validating the results. To this end, this research proposal aims to fabricate an instrumented water tank that can be used to measure normal and shear forces on a hull-like surface in addition to visualization of the Bernoulli pad dynamics. The proposed experimental test-bed will hasten the development of a prototype device whose e#cacy can then be determined using ship hull-like surfaces cultivated with di#erent levels of biofoul-ing at the ONR-funded Center for Corrosion and Biofouling Control at the Florida Institute of Technology.In addition to biofouling mitigation, the instrumented water tank will enhance research towards development of a new type of propulsion mechanism for underwater vehicles. The principal investigator developed a method for producing #sh-like motion with prior funding from ONR. In this method, a tail-like #exible element is designed to undergo #utter instability. A #uid jet exiting the tip of the tail produces the instability and thrust is produced by the synergistic combination of the jet and the #uttering tail. Preliminary work has shown that the traveling waveforms produced by the tail~s jet-driven #utter instability produces thrust exceeding the momentum #ux from the jet exiting the tail. Modeling has also indicated that the vehicle can be steered by carefully modulating the velocity of the jet. The objective of the research is to optimize the tail geometry to improve propulsive e#ciency and optimizing the temporal variation of the jet velocity to enable quick turning maneuvers. This will be achieved by a combination of CFD simulations and carefully designed experiments. The instrumented water tank will be used to measure the thrust developed by the #uttering tail and the turning moments generated by the tail when used as a control surface.The investigator has done prior research in bipedal locomotion and one of his current research areas is impulsive control of dynamical systems. The proposed water tank facility with its high-speed camera will help the PI improve his understanding of high-speed impact with water and contribute signi#cantly towards his ambitious goal of bipedal locomotion on water using impulsive actuation. There are several faculty members in the department of mechanical engineering involved in #uid mechanics research. Their individual research facilities include wind and water tunnels; these tunnels have narrow dimensions and are therefore not suitable for performing the experimental investigations proposed herein.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jul 10, 2018
- Source ID
- N000141812230
Entities
People
- Ranjan Mukherjee
Organizations
- Michigan State University
- Office of Naval Research
- United States Navy