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Energy-efficient large medium-speed catamarans : hull form design by full-scale CFD simulations

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Haase, M (2015) Energy-efficient large medium-speed catamarans : hull form design by full-scale CFD simulations. PhD thesis, University of Tasmania.

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Abstract

Large medium-speed catamarans are currently under development as a new class of vessel for
economically efficient and more environmentally sustainable fast sea transportation. Their
design is based on current high-speed catamarans, to adopt advantages such as large deck
areas and low wave-making resistance, but they will operate at lower speeds and carry a
higher deadweight to obtain higher transport efficiency. They operate at speeds around the
main drag hump, where the wave-making drag coefficient is at its maximum. Hence this speed
range is usually avoided by boat designers no precise guidelines for hull form design of large
medium-speed catamarans are present to operate efficiently in this generally unfavourable
speed spectrum.
Literature has been surveyed to derive hull form parameters that provide low drag for monohulls
and catamaran vessels. Based on these findings a hull form family was developed with
demihull slenderness ratios ranging from 9 to 15 and the hydrodynamic performance was
evaluated at Froude numbers from 0.25 up to 0.49 to derive design parameters with the
lowest drag and highest transport efficiency. These parameters corresponds to vessel sizes
from 110 m to 190 m and speeds of 16 to 41 knots. A novel CFD-based approach has been
developed to provide more accuracy to the final drag prediction at full scale. It was verified
using results of model scale experiments of a 98 m and a 130 m catamaran and validated
with results obtained from sea trial measurements, in deep as well as in shallow water. Furthermore,
its capability to replicate the flow past a typical deep partially ventilated transom has been investigated using model scale experiments. The key advantage of this method is that the same computational mesh can be used for model-scale verification and full-scale predictions.
The computational full-scale simulation approach was found to be capable of predicting the
drag force within 5% of results derived from full-scale measurements and extrapolated model
test data. In addition it has been shown to correctly predict steady and unsteady shallow
water effects. Also the ventilation process of the transom stern has been experimentally
validated and the ow feature in the stagnant zone past the partially ventilated transom was
identified as a non-shedding squashed horseshoe vortex. The lowest drag can be achieved for catamarans with demihull slenderness ratios of 11 to 13 and hulls of 150 m in length provided highest transport efficiency for speeds of 20 to 35 knots at a light displacement, and 170 m and 190 m for a medium and a heavy displacement respectively.
Finally, when comparing the results to contemporary large and fast catamarans carrying
equivalent deadweight and travelling at the same speed, fuel savings up to 40% can be
achieved if a hull of 150 m instead of 110 m length is used. This demonstrates that large medium
catamarans have the potential to be a fuel-efficient alternative for a successful future
of fast sea transportation.

Item Type: Thesis (PhD)
Keywords: Fuel efficient fast sea transportation, transport efficiency, simulation-based design, shallow water, transom ventilation
Copyright Information:

Copyright 2015 the Author

Additional Information:

Chapter 2 has been published in a modified version as: Haase, M., Davidson, G., Friezer, S., Binns, J., Thomas, G., Bose, N., Transaction of the Royal Institution of Naval Architects, Part A - International journal of maritime engineering, 2012. On the macro hydrodynamic design of highly efficient medium-speed catamarans with minimum resistance, 154. A3, 131-142. It has been removed for copyright or proprietary reasons

Chapter 3 appears to be the equivalent of a pre-print version of an article published as: Haase, M., Zurcher, K., Davidson, G., Binns, J., Thomas, G., Bose, N., 2016. Novel CFD-based full-scale resistance prediction for large medium-speed catamarans, Ocean engineering, 111, 198-208

Chapter 4 appears to be the equivalent of a pre-print version of an article published as: Haase, M., Davidson, G., Binns, J., Thomas, G., Bose, N., 2017. Full-scale resistance prediction in finite waters: A study using computational fluid dynamics simulations, model test experiments and sea trial measurements, Proceedings of the Institution of Mechanical Engineers, Part M: Journal of engineering for the maritime environment, 23(1), 316-328

Chapter 5 appears to be the equivalent of a pre-print version of an article published by Taylor & Francis in Ship technology research on 21 April 2015, available online: http://www.tandfonline.com/10.1080/09377255.2015.1119922

Chapter 6 has been published in a modified version as: Haase, M., Davidson, G., Friezer, S., Binns, J., Thomas, G., Bose, N., Transaction of the Royal Institution of Naval Architects, Part A - International journal of maritime engineering, 2015. Hydrodynamic hull form design space exploration of large medium-speed catamarans using full-scale CFD, 157. A3, 161-174. It has been removed for copyright or proprietary reasons

Date Deposited: 17 Nov 2016 04:30
Last Modified: 15 Mar 2017 01:56
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