Experiments and numerical simulations of the dynamics of an R.O.V. thruster during maneuvering
Citable URI
https://hdl.handle.net/1912/5672DOI
10.1575/1912/5672Keyword
Remote submersibles; HydrodynamicsAbstract
Propeller dynamics have typically been ignored in controller
design, lumped into the category of 'unmodeled dynamics.' This
is acceptable for propellers operating at constant speed in
relatively uniform flows. Operational parameters of small
remotely operated vehicles and autonomous underwater vehicles
require a great deal of transient operation of the propellers.
This and the small mass of the vehicles make the dynamics of the
propellers a significant factor in vehicle control. Expanding
roles of these vehicles require improved control and therefore
improved understanding of the dynamics of the thrusters during
maneuvering.
In this thesis, the dynamics of maneuvering thrusters were
explored through numerical simulation and experiments. Vortex
lattice propeller code developed for use with nonuniform inflow
was adapted to incorporate varying propeller speed and inflow
velocity. Test runs were made using a three bladed propeller.
Experiments were preformed on a thruster from the ROV Jason using
the water tunnel at the Massachusetts Institute of Technology.
The thruster incorporated a ducted three bladed propeller. Runs
were made using step changes in shaft velocity as well as
sinusoidal perturbations on top of steady state velocities. Runs
were also made incorporating fully reversing propeller operation.
Experiments were done with and without the duct in place.
The numerical simulation and experimental results showed that
accelerating propeller angular velocity created higher thrust
values than steady state propeller operation at the corresponding
instantaneous shaft velocity. Decelerating angular velocities
created lower thrust values. This is attributed to a lag in the
local flow velocity due to the momentum of the fluid. For the
case of the accelerating propeller, the angle of attack at the
blade is higher, resulting in higher lift force and greater
thrust. Errors in the numerical code at low advance coefficients
prevented direct comparison of numerical code results to
experimental results.
Description
Submitted in partial fulfillment of the requirements for the degree of Master of Science at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution September 1996
Suggested Citation
Thesis: Knowles, James H., "Experiments and numerical simulations of the dynamics of an R.O.V. thruster during maneuvering", 1996-09, DOI:10.1575/1912/5672, https://hdl.handle.net/1912/5672Related items
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