Table Of Contenti
Wave Energy Devices
ii
iii
Wave Energy Devices
Design, Development, and
Experimental Studies
Srinivasan Chandrasekaran
Faisal Khan
Rouzbeh Abbassi
iv
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© 2022 Srinivasan Chandrasekaran, Faisal Khan, and Rouzbeh Abbassi
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ISBN: 978- 1- 032- 25075- 5 (hbk)
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DOI: 10.1201/ 9781003281429
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Contents
Preface ........................................................................................................................ix
Authors .......................................................................................................................xi
Chapter 1 Ocean Waves and Wind Forces: Basics .................................................1
1.1 Ocean Environment .....................................................................1
1.2 Wave Theories .............................................................................2
1.3 Stoke’s Fifth- Order Theory .........................................................6
1.4 Wave Spectra .............................................................................16
1.4.1 PM Spectrum for Wave Loads .....................................16
1.4.2 Modified PM Spectrum (Two Parameters, H, ω) ......16
s 0
1.4.3 International Ship Structures Congress (ISSC)
Spectrum (Two Parameters, H, ω) .............................16
s
1.4.4 Joint North Sea Wave Project (JONSWAP)
Spectrum (Five Parameters, H, ω , γ, τ, τ) ..............17
s 0o a b
1.5 Wind and Current ......................................................................22
1.5.1 Wind Spectra ...............................................................28
1.5.2 Current .........................................................................31
Exercises ..............................................................................................32
Chapter 2 Perforated Cylinders and Applications ................................................33
2.1 Introduction ...............................................................................33
2.2 Force Reduction in the Inner Cylinder ......................................33
2.3 Effect of Annular Spacing and Perforation Ratio on Force
Reduction ..................................................................................37
2.4 Effect of Perforation Parameters on Force Reduction ..............41
2.5 Twin Perforated Cylinders ........................................................47
Exercises ..............................................................................................59
Chapter 3 Floating Wave Energy Converter .........................................................61
3.1 Introduction ...............................................................................61
3.2 Wave- to- Wire Transfer ..............................................................65
3.3 Numerical Modeling .................................................................66
3.4 Frequency- Domain Modeling ...................................................69
3.5 Time- Domain Modeling ...........................................................74
3.5.1 Linear Time- Domain Model (LTD).............................75
3.6 Computational Tools .................................................................77
3.7 Multibody Floating Wave Energy Converter ............................77
3.8 Hydrodynamic Coefficients of Floating Wave Energy
Converters .................................................................................91
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3.9 Wave Power ...............................................................................94
3.9.1 Regular Waves .............................................................94
3.9.2 Irregular Waves ............................................................95
3.10 Performance Curves with Virtual Power Take- Off
System .....................................................................................100
3.11 Analysis with Hydraulic Power Take- Off System ..................104
3.11.1 Governing Parameters ...............................................104
3.12 Practical Guide to Design of Hydraulic Power Take- Off
System .....................................................................................109
3.13 Numerical Studies on Hydraulic Power Take- Off
Systems ...................................................................................110
3.14 Floating Wave Energy Converter Response without Power
Take- Off System .....................................................................116
3.15 Floating Wave Energy Converter with a Novel Hydraulic
Power Take- Off System ..........................................................124
3.16 Failure Assessment of Floating Wave Energy Converter ........134
Exercises ............................................................................................141
Chapter 4 Double- Rack Mechanical Wave Energy Converter ...........................143
4.1 Introduction .............................................................................143
4.2 Mechanical Wave Energy Converter .......................................144
4.2.1 Equation of Motion ...................................................145
4.2.2 Power Take- Off System Design ................................147
4.2.3 Experimental Studies .................................................152
4.3 Double Rack Mechanical Wave Energy Converter .................155
4.3.1 Experimental Studies on Double Rack Mechanical
Wave- Energy Converters ...........................................156
4.4 Failure Assessment ..................................................................158
4.4.1 Conducting Design Failure Mode and
Effect Analysis ..........................................................160
4.5 Failure Mode and Effect Analysis of Mechanical
Wave- Energy Converter ..........................................................162
4.6 Deep-Ocean Wave Energy Converter: Conceptual Design .....163
4.6.1 Geometric Design of the Device ...............................163
4.7 Working Principle of Deep Ocean Wave
Energy Converters ...................................................................166
4.8 Experimental Investigations on Deep Ocean Wave Energy
Converters ...............................................................................168
4.8.1 Cylindrical Float ........................................................172
4.8.2 Cylindrical Float Integrated with Fin ........................176
4.9 Multi- Utility Development Devices ........................................185
4.9.1 Applications of TSUSUCA- DOLPHIN ....................196
4.9.2 Workable Alternatives ...............................................197
4.9.3 Cost Benefits .............................................................199
Exercises ............................................................................................201
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Contents vii
Chapter 5 Offshore Wind Turbines ....................................................................203
5.1 Introduction .............................................................................203
5.1.1 Support Systems for Wind Turbines ..........................204
5.2 Wind Power .............................................................................206
5.3 Numerical Tools ......................................................................207
5.4 Offshore Wind Turbine Classifications ...................................208
5.5 Offshore Floating Wind Turbine: Components .......................209
5.6 Offshore Floating Wind Turbines............................................209
5.6.1 Single Point Anchor Reservoir Type .........................210
5.6.2 Tension- Leg Platform Type .......................................212
5.6.3 Pontoon (Barge) Type ................................................213
5.6.4 Semi- Submersible Type .............................................214
5.6.5 Triceratops .................................................................215
5.6.6 Triceratops- Supported Wind Turbines.......................219
5.7 Experimental and Numerical Analyses ...................................220
5.8 Mathematical Background ......................................................222
5.8.1 Blade Momentum Theory .........................................222
5.8.2 Blade Element Theory ...............................................225
5.9 Aero- Elastic Model .................................................................227
5.9.1 Kane Method .............................................................228
5.9.2 Wind Load .................................................................228
5.9.3 Wind Shear Effect .....................................................229
5.10 Normal Turbulence Model ......................................................229
5.11 Wind Spectrum .......................................................................230
5.12 Numerical Analysis of Triceratops- Supported
Wind Turbine ..........................................................................230
5.13 Responses under Operable Loads and Parked Conditions ......236
5.14 Dynamic Tension Variation of Tethers ....................................238
Exercises ............................................................................................241
References ..............................................................................................................243
Index .......................................................................................................................255
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ix
Preface
The book Wave Energy Devices: Design, Development, and Experimental Studies is
an intensive effort, backed up with the very rich experiences in teaching, research,
and industrial consultancies of the authors with international exposure. The
contents are distributed in five chapters, each focusing on developing expertise and
strengthening the research abilities in the wave energy harvest. Detailed discussions
on the design and development of floating wave energy converters, mechanical wave
energy converters, and offshore wind turbines are testimonies of research- backed
development on the new arena of wave energy. There has been a positive kick-s tart
of high- value research contributions by scientists worldwide, based on the detailed
experimental and numerical studies presented in various chapters. Industrial-
backed experience possessed by the authors in designing and developing offshore
wind turbines in alignment with the international guidelines are added factors to
this book. Although a classroom mode of presentation is not adopted, the contents
discussed in the step- by- step procedures help us to understand the design and
development of wave energy devices from scratch. The inclusion of the conceptual
development of multi- utility development devices like TSUSUCA is a stimulator
for young researchers to diversify their ideas for commercial success. The use of
perforated cylinders, though finding a wider application in coastal structures, wave
energy harvesting will result in force reduction on members. The basic concepts of
ocean waves and wind will help graduate engineers and researchers strengthen their
numerical modeling techniques while helping practicing engineers revisit the math-
ematical models. Failure assessment, discussed in a few chapters, helps achieve a
complete product development of wave energy devices using simple but effective
reliability tools. A variety of mechanical components, their sizing, design principles,
and final product development help readers achieve a workflow in the design of wave
energy devices.
The authors sincerely thank various researchers who contributed to the
chapters by sharing their findings and knowledge. The lead editor, in particular,
thanks the Chairman of the Center for Continuing Education and the administra-
tive authorities of the Indian Institute of Technology Madras for their generous
support extended in conducting the experiments, identifying industrial partners
for technology transfer, and assisting in filing patents of the developed wave
energy devices. The editors also extend their sincere gratitude to the administra-
tive authorities of the School of Engineering, Macquarie University, Australia, and
the Process Safety Center, Texas A&M University, United States. The association
of the authors with the schools of engineering of international repute strengthened
the editors’ confidence in writing this book and they sincerely thank the authors
for providing rich research and an academic environment in which to complete
this book. The contributions made by Dr. N. Madhavi, Freelance Technical
Designer, San Diego, United States, in Chapter 2 are sincerely acknowledged.
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