MS Thesis R. Hager - Hawaii National Marine Renewable Energy ...

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221 2P gA C(77)max g2 3.8 Maximum Power Absorption EfficiencyThe goal of this thesis is to study the maximum power absorption efficiency for variouslyshaped bodies. The maximum power absorption efficiency, λ, is the ratio of mean powerabsorbed by the body to the mean power in unit crest length of a regular wave-train.2P maxP w (78)Maximum Power absorption efficiency for a two-dimensional single, heaving bodyCombinng Eq. (72), Eq. (77), and Eq. (78) reults in the maximum power absportionefficiency for a two-dimensional, single, heaving body:22 (79) It is apparent from Eq. (79) that directionality of the radiated wave is desirable. With asymmetric body, the radiated wave amplitude will be equal at positive and negative infinity,thus reducing the maximum power absorption efficiency to 50% (Falnes, 2007). However, ifthe wave is only radiated in the positive direction the maximum power absorption efficiencyis theoretically 100% (Falnes, 2007). This directionality of the radiated wave accounts for thesuccess of Salter’s Duck, and is further explored in this work (Falnes, 2007).254
CHAPTER 4. NUMERICAL SIMULATIONSThe software package AQWA v.14.0 by ANSYS is used to analyze the diffraction problemfor a single, two-dimensional body impinged by a regular, harmonic, linear wave. AQWAapplies the Green Function Method to solve for hydrodynamic and hydrostatic quantities.More specifically, AQWA-LINE evaluates the linear response of a fixed body subjected toregular, linear waves using diffraction theory, as presented in Chapter 3.4.1 Numerical ProcedureAQWA is used to solve for the excitation force for 39 bodies. The excitation force iscalculated as the incident wave approaches the body from 0° and 180°. Where, the excitationforce measured as the wave impinges the body’s curved face is denoted as 0 ○ , and theexcitation force measured as the wave impinges the body’s flat face is denoted 180 ○ . Thecomplex amplitude of the excitation force is then used to calculate the radiated waveamplitude at positive and negative infinity with Eq. (58):AgCgiXi 2where, the group velocity is calculated using Eq. (33):C g 1 2kd 1k 2 sinh(2kd)Using the radiated wave amplitude at positive and negative infinity, the maximum powerabsorption efficiency is calculated with Eq. (79): 22 255
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Geometric Effects on Maximum Power
Page 3 and 4: ABSTRACTNumerical simulations are c
Page 5 and 6: 3.7 Absorbed Wave Power ...........
Page 7 and 8: LIST OF FIGURESFigurePageFigure 1.1
Page 9 and 10: NOMENCLATUREA=incident wave amplitu
Page 11 and 12: 1.2 Advantages of Wave EnergyAdvant
Page 13 and 14: for various projects. Included in t
Page 15 and 16: pollution would occur from hydrauli
Page 17 and 18: Figure 1. 7 Average Annual Wave Pow
Page 19 and 20: Backer (2009) numerically and exper
Page 21 and 22: CHAPTER 2. WAVE ENERGY CONVERSION D
Page 23 and 24: 2.3 OrientationOrientation is defin
Page 25 and 26: Figure 2.4 Oscillating Water Column
Page 27 and 28: 2.5 Reference PointMeans of reactio
Page 29 and 30: Linear GeneratorTurbineRotary Gener
Page 31 and 32: Table 2. 1 WEC ClassificationsDevic
Page 33 and 34: 33P.T.O.MooringReferencePointOperat
Page 35 and 36: CHAPTER 3. THEORY AND GOVERNING EQU
Page 37 and 38: F(x,z,t) z 0DFDtFt u F 0 0 (4
Page 39 and 40: in ni(13)on S for i=1, 3in( r n)i3
Page 41 and 42: I iAg e ekz i( kx t)(30)cosh( k(z
Page 44 and 45: where ijkis the permutation symbol.
Page 46 and 47: Mw k ieitS( D I) ijkrinjdS(46)3.3.3
Page 48 and 49: Due to Kirchhoff decomposition, rec
Page 50 and 51: TE KE PE 20L Asin(kx) 1 2(61)dV d
Page 52 and 53: P I Iw dS (70)tnSIf the column
Page 56 and 57: 4.2 AQWA Modeling ProcedureThe user
Page 58 and 59: : Local data has changed, and the c
Page 60 and 61: Figure 4. 5 Drawing in Design Modul
Page 62 and 63: 12. Delete all lines inside the cur
Page 64 and 65: 22. Edit the details of the slice u
Page 66 and 67: Figure 4. 15 Details of the Part7.
Page 68 and 69: Figure 4. 17 Details of the Mesh4.2
Page 70 and 71: Figure 4. 21 Detials of the Wave Di
Page 72 and 73: 5. Highlight Diffraction + Froude-K
Page 74 and 75: Table 4.1 Body Dimensions for Numer
Page 76 and 77: concavity from concave down to conc
Page 78 and 79: Figure 4. 29 Maximum Power Absorpti
Page 80 and 81: Table 4. 3 Numerical ResultsBodyNo.
Page 82 and 83: BodyNo.Bodyλ atT=2.1λ atT=1.0λ a
Page 84 and 85: WAVEFigure 5. 1 Body Faces Wave Mak
Page 86 and 87: The body connects to the aluminum p
Page 88 and 89: also allowed for flexibility in cre
Page 90 and 91: AB1 23 4 5 6 7CD8 9 10 11EFigure 5.
Page 92 and 93: and minimum voltage range of the DA
Page 94 and 95: Figure 5. 11 Deleting a Step from L
Page 96 and 97: Figure 5. 14 Recording Options, Sig
Page 98 and 99: Figure 5. 17 Right-mouse Click on t
Page 100 and 101: Zero-OffsetThe Zero-Offset step rem
Page 102 and 103: Figure 5. 24 Filter Step Set-up, Co
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5.6 Data ProcessingFigure 5. 26 Wav
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5.8 Experimental DiscussionAs menti
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5.8.3 Suggestions for Future Resear
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110ikxxRekddzkgkn )cosh())(cosh(,
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Proof M ij and B ij are Symmetric T
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BIBILIOGRAPHYANSYS. (n.d.). ANSYS A
Page 116:
Trust, C. (2011). Capital, Operatin
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MS Thesis R. Hager - Hawaii National Marine Renewable Energy ...

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