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290 M. Seidel and J. Gößwein account. Furthermore, finding equivalent hydrodynamic coefficients to take account of many members proves to be difficult in many cases. – The use of foundation models in two different programs, which need to be harmonized, e.g. in terms of wave loads, creates an additional interface with more possibilities for errors in the process. The shortcomings of this approach lead to the development of a new solution with a higher degree of integration of the two programs used [3]. The characteristics of this integrated, sequential approach are: – Two specialized programs – Flex 5 for the wind loads and ASAS(NL) for the wave loads – have been adapted to each other such that they can be used sequentially to obtain a solution for the integrated system. – The general approach to achieve this has been based on the existing modelling in Flex 5 which uses generalized degrees of freedom to model the substructure. Six generalized degrees of freedom are used. – Although the methodology is still an approximation, good results can be achieved for many structures. Good knowledge about the methodology and its limitations are however required for a safe and efficient design. A flow chart of the methodology is shown in Fig. 53.3. 53.3.2 Substructure Concepts So far, most of the existing Offshore turbines have been installed with Monopile or gravity base substructures. Due to the size of the 5M and the associated loading, Monopiles are getting quite large and thus other concepts may become more interesting, especially for water depths in excess of 10 m. Extensive work has been done for the DOWNVInD project with two turbines for the demonstration phase which will be installed in 45 m water depth in 2006. Initially, Tripod foundations which had a weight of over 1,000 t were foreseen for this project. This selection has been revisited as REpower has worked closely with OWEC Tower – a Norwegian company with a background in offshore oil and gas which is now specializing in offshore wind turbines – and it was found that the OWEC Jacket Quattropod (OJQ) offers a much better chance for economic optimization due to lower weight of the substructure. The final design of this structure is currently ongoing and fabrication is expected to commence end of 2005. Other concepts under evaluation include concrete substructures which are an interesting alternative due to the low material cost. Different concepts are offered on the market, primarily from large building contractors which aim at gaining market shares in this evolving market. 53.4 Installation Methods Installation concepts are of course closely related to the structural concepts. Installations so far have been executed in a very similar way. Basically the
53 Advances in Offshore Wind Technology 291 Integrated linearized Flex 5 - ASAS(NL) load calculations Excel ASAS(NL) Flex 5 Generate model and load cases Write ASAS(NL) input files and batch files Init deflection shapes Flex 5 files generation run (stiffness, damping, mass matrix and loading history) Retrieval run Extract time series of member forces Integrated windwave loading analysis Rainflow counting Fig. 53.3. Overview of calculation process components substructure, tower, nacelle and rotor are installed sequentially, very much in the same way as onshore construction is performed. The DOWNVInD project will feature significant innovative approaches. Due to the fact that conventional installation is not feasible as jack-ups for 45 m water depth are not available for economical conditions, an installation in two parts is foreseen. The OJQ will be installed and piled first and the full assembly of wind turbine, rotor and tubular tower will be installed as one complete unit subsequently. A detailed investigation on how and if this approach can be made to work is currently underway. References 1. Schubert, M.; Gößwein, J.: Aufstellung und erste Betriebserfahrungen der weltweit größten Windenergieanlage REpower 5M. Offshore-Symposium GL-Windenergie. Hamburg 2005
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Wind Energy Proceedings of the Euro
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Prof. Dr. Joachim Peinke Dr. Stepha
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VI Preface been presented, spanning
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VIII Contents 3.3 Stochastic Wind F
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X Contents 12.6 Subgrid Scale Turbu
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XII Contents 22 Stochastic Small-Sc
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XIV Contents 32 Handling Systems Dr
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XVI Contents 41 3D Numerical Simula
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XVIII Contents 51 Comparing WAsP an
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XX Contents 58.3 Ultra-High Perform
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XXII List of Contributors Lars Berg
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XXIV List of Contributors Renata Gn
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XXVI List of Contributors A. Kiss D
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XXVIII List of Contributors El˙zbi
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XXX List of Contributors Ivo Sláde
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1 Offshore Wind Power Meteorology B
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1 Offshore Wind Power Meteorology 3
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1 Offshore Wind Power Meteorology 5
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2 Wave Loads on Wind-Power Plants i
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Trubaduren 2 Wave Loads on Wind-Pow
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Base moment (10 6 Nm) 0.4 0.2 −0.
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2 Wave Loads on Wind-Power Plants i
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3 Time Domain Comparison of Simulat
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3 Time Domain Comparison Using Cons
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7.0 6.0 5.0 4.0 3.0 2.0 1.0 0.0 3 T
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4 Mean Wind and Turbulence in the A
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5 Wind Speed Profiles above the Nor
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5 Wind Speed Profiles above the Nor
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Height [m] 100 90 80 70 60 50 40 30
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6 Fundamental Aspects of Fluid Flow
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f Suu(f, z) / σ 2 u(z) 10 0 10 −
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a) c) −0,375 6 Fluid Flow over Co
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7 Models for Computer Simulation of
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y/h 2.5 2 1.5 1 0.5 0 7 Models for
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8 Power Performance via Nacelle Ane
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9 Pollutant Dispersion in Flow Arou
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x1/B 0.3 0.5 0.8 1.0 9 Pollutant Di
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9 Pollutant Dispersion in Flow Arou
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10 On the Atmospheric Flow Modellin
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11 Comparison of Logarithmic Wind P
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Height above ground in m 100 90 80
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12 Turbulence Modelling and Numeric
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13 Gusts in Intermittent Wind Turbu
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Durations (s) 25 20 15 10 5 13 Gust
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14 Report on the Research Project O
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height z (m) 100 80 60 40 20 0 14 R
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14.6 Outlook 14 Report on the Resea
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15 Simulation of Turbulence, Gusts
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S(ƒ)(m/s) 2 /Hz 15 Simulation of T
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15 Simulation of Turbulence, Gusts
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16 Short Time Prediction of Wind Sp
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ms prediction error [m/s] 16 Short
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16 Short Time Prediction of Wind Sp
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17 Wind Extremes and Scales: Multif
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Log10 E(k)*k**(5/3) 6 4 2 0 5/3 cor
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17.3 Discussion and Conclusion 17 W
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18 Boundary-Layer Influence on Extr
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z/H (a) (b) 4 2 18 Boundary-Layer I
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18.6 Concluding Remarks 18 Boundary
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19 The Statistical Distribution of
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19 The Statistical Distribution of
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20 Superposition Model for Atmosphe
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h(u) 0.5 0.3 0.1 20 Superposition M
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21 Extreme Events Under Low-Frequen
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21 Extreme Events Under Low-Frequen
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22 Stochastic Small-Scale Modelling
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p(σ⏐u) 1 0.8 0.6 0.4 0.2 22 Stoc
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22 Stochastic Small-Scale Modelling
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23 Quantitative Estimation of Drift
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24 Scaling Turbulent Atmospheric St
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24 Scaling Turbulent Atmospheric St
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25 Wind Farm Power Fluctuations P.
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25 Wind Farm Power Fluctuations 141
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d rc q rc V 0 q V 25 Wind Farm Powe
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References 25 Wind Farm Power Fluct
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26 Network Perspective of Wind-Powe
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27 Phenomenological Response Theory
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28 Turbulence Correction for Power
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28 Turbulence Correction for Power
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29 Online Modeling of Wind Farm Pow
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29 Online Modeling of Wind Farm Pow
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30 Uncertainty of Wind Energy Estim
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31 Characterisation of the Power Cu
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32 Handling Systems Driven by Diffe
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32 Handling Systems Driven by Diffe
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33 Experimental Researches of Chara
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33 Experimental Researches of Chara
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34 Methodical Failure Detection in
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34 Methodical Failure Detection in
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35 Modelling of the Transition Loca
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35 Modelling an Airfoil with Surfac
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(Cl/Cd)max 120 110 100 90 80 70 60
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35 Modelling an Airfoil with Surfac
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36 Helicopter Aerodynamics with Emp
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37 Determination of Angle of Attack
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37 Determination of Angle of Attack
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Drag coefficient 0.5 0.4 0.3 0.2 0.
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38 Unsteady Characteristics of Flow
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PSD PSD 38 Unsteady Characteristics
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39 Aerodynamic Multi-Criteria Shape
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39 Multi-Criteria Shape Optimizatio
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39 Multi-Criteria Shape Optimizatio
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40 Rotation and Turbulence Effects
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Cp Xsep/c 1 0.6 0.2 −0.2 −0.6
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Standard deviation of Cp 0.7 0.6 0.
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41 3D Numerical Simulation and Eval
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41 3D-CFD-Simulation of a Wind Turb
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42 Performance of the Risø-B1 Airf
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42 Performance of the Risø-B1 Airf
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43 Aerodynamic Behaviour of a New T
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43 Aerodynamic Behaviour of a New T
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Page 271 and 272: 44 Numerical Simulation of Dynamic
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Page 275 and 276: 45 Modeling of the Far Wake behind
Page 277 and 278: 8 6 uz 4 2 45 Modeling of the Far W
Page 279 and 280: 46 Stability of the Tip Vortices in
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Page 283 and 284: 47 Modelling Turbulence Intensities
Page 289 and 290: 48 Numerical Computations of Wind T
Page 291 and 292: Z X Y 48 Numerical Computations of
Page 293 and 294: References 48 Numerical Computation
Page 295 and 296: 49 Modelling Wind Turbine Wakes wit
Page 297 and 298: U mean / U ref 1 0.9 0.8 0.7 49 Mod
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Page 301 and 302: 50 Prediction of Wind Turbine Noise
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Page 305 and 306: 51 Comparing WAsP and Fluent for Hi
Page 307 and 308: Table 51.1. Measurements and simula
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Page 311 and 312: 52 Fatigue Assessment of Truss Join
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Page 323 and 324: 54 Benefits of Fatigue Assessment w
Page 325 and 326: ∆σN [N/mm²] 100 10 54 Benefits
Page 327 and 328: 55 Extension of Life Time of Welded
Page 329 and 330: Transverse residual stresses [N/mm
Page 331 and 332: 56 Damage Detection on Structures o
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Page 335 and 336: 57 Influence of the Type and Size o
Page 337 and 338: [W/m 2 ] q t [W/m 5000 4000 3000 20
Page 339 and 340: 58 High-cycle Fatigue of “Ultra-H
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Page 343 and 344: 59 A Modular Concept for Integrated
Page 349 and 350: 60 Solutions of Details Regarding F
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Page 353 and 354: 60 Solutions of Details Regarding F
Page 355 and 356: 61 On the Influence of Low-Level Je
Page 357 and 358: Relative Power and Loading [%] 61 O
Page 359 and 360: 62 Reliability of Wind Turbines Exp
Page 361 and 362: 62 Reliability of Wind Turbines 331
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