Acoustic minimization of Ocean Twilight Zone Vehicle, Mesobot

Thumbnail Image
Date
2023-09
Authors
Davis, Cameron J.
Linked Authors
Alternative Title
As Published
Date Created
Location
DOI
10.1575/1912/67668
Related Materials
Replaces
Replaced By
Keywords
Acoustics
Communication methods
Underwater vehicles
Abstract
The OTZ is defined as the region of the water column between 200 and 1,000 meters in depth. It plays a vital role in the global carbon cycle, pushing carbon from the surface layer into the deep ocean. It has a very diverse population of fauna, known and unknown, that migrate up and down the water column to feed and reproduce. The migration pattern occurs based on the amount of radiated sunlight into the water column. The mid-water column vehicle, Mesobot, was designed to mimic the migration patterns of mesopelagic organisms. Unmanned Underwater Vehicles (UUVs) have become a staple of ocean exploration for years, going where man is not able to. Although much quieter than noise from shipping traffic, the noise radiated from Mesobot could present potential for error in observation, tracking, and sampling. In this thesis, I have analyzed the effect of commutation methods and propeller design on the acoustic noise radiated from a single BlueRobotics T200 thruster. The propeller design choices are a standard three-blade propeller and a three-blade toroidal propeller. The commutation methods analyzed are trapezoidal control and field-oriented control. After analyzing four different alternatives, quantitative evidence was found to recommend using field-oriented control as the commutation scheme to minimize the radiated noise from the thrusters on Mesobot. The radiated noise from the thurster was dominated by motor noise, and no conclusive evidence was found to recommend the three-blade propeller over the toroidal propeller.
Description
Submitted in partial fulfillment of the requirements for the degree of Master of Science in Mechanical Engineering at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution September 2023.
Embargo Date
Citation
Davis, C. J. (2023) Acoustic minimization of Ocean Twilight Zone Vehicle, Mesobot [Master's thesis, Massachusetts Institute of Technology and Woods Hole Oceanographic Institution]. Woods Hole Open Access Server. https://doi.org/10.1575/1912/67668
Cruises
Cruise ID
Cruise DOI
Vessel Name
Collections