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研究生： 林振明
Lin, Chen-Ming
論文名稱： 大直徑圓柱體於修正莫里森方程式的實驗驗證及其對離岸風機結構的影響研究
Experimental Validation of Modified Morison's Equation for Large-Diameter Cylinders and Study on its Impact on Offshore Wind Turbine Structures
指導教授： 朱聖浩
Ju, Shen-Haw
學位類別： 碩士
Master
系所名稱： 工學院 - 土木工程學系
Department of Civil Engineering
論文出版年： 2025
畢業學年度： 113
語文別： 英文
論文頁數： 142
中文關鍵詞： 離岸風機 、波浪載重 、實驗 、莫里森方程 、斯托克斯理論 、流函數理論 、有限元素分析 、NREL 22MW
外文關鍵詞： offshore wind turbines, wave loads, experimental, Morison's equation, Stokes theory, stream function theory, finite Elemental Analysis, NREL 22MW
相關次數： 點閱：35  下載：10 
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    • 本研究探討了大直徑圓柱體在波浪載重下的行為，並將研究內容分為兩個主要部分。第一部分主要說明波浪載重的計算方法以及使用實驗方式進行驗證。傳統上，波浪載重通常使用莫里森方程式進行計算。然而，當波長與圓柱體直徑的比值小於5時，使用此方程式會產生顯著誤差。為了解決這一問題，本研究對莫里森方程式中的慣性係數 C_M 進行了修正，以提高在小波長情況下的計算精度。並在國立成功大學水工所的大型斷面水槽進行造波驗證實驗，結果顯示，修正後的莫里森方程式能更準確地反映實際情況。
    第二部分則探討了風機模擬中常用的風場模型，並描述了如何模擬不規則波的波浪，及使用有限元素分析程式（AN）來計算波浪載重。而為了突顯有無修正方程式的差異，本研究比較了22MW固定式風機與浮式風機在不同波高週期情況下的波浪力，並對比了未修正的莫里森方程式與修正後莫里森方程式在波浪力計算上的差異。研究發現，大尺寸圓柱體（即浮式風機的浮筒）在有無修正莫里森公式的計算下，比起固定式風機的計算差異更為顯著。這些比較結果的準確性將有助於後續風機設計的評估，例如疲勞分析，從而為離岸風機的設計與運營提供更可靠的數據支持。
    本實驗是與博士班的邱覺生學長共同進行，基於合作的關係，部分資料可能會與其研究有所重疊。本研究所使用的分析方法及設計程式由朱聖浩教授研究團隊共同開發，程式及研究成果皆為公開資源，朱聖浩教授與本文作者雙方均可獨立發表論文。

    This study investigates the behavior of large-diameter cylinders under wave loading and is divided into two main parts. The first part mainly explains the calculation method of wave load and verifies it using experimental methods. Traditionally, wave loads are usually calculated using Morison’s equation. However, when the ratio of wavelength to cylinder diameter is less than 5, using this equation can produce significant errors. To solve this problem, this study corrected the inertia coefficient C_M in Morison’s equation to improve the calculation accuracy in the case of small wavelength. Wave-generating verification experiments were conducted in a large-section flume at the Institute of Hydraulic Engineering at National Cheng Kung University. The results showed that the revised Morison’s equation can more accurately reflect the actual situation.
    The second part discusses the wind field models commonly used in wind turbine simulations and describes how to simulate irregular waves and calculate wave loads using the Finite Element Analysis (AN) program. To highlight the difference between the equation with and without correction, this study compares the wave forces on a 22 MW fixed wind turbine and a floating wind turbine under different wave heights and periods. It also compares the uncorrected Morison's equation with the corrected Morison's equation in terms of wave force calculations. The study found that the calculation differences for large-sized cylinders (such as the pontoons of floating wind turbines) with and without the modified Morison formula are more significant than those for fixed wind turbines. The accuracy of these comparison results will aid in the subsequent evaluation of wind turbine designs, such as fatigue analysis, thereby providing more reliable data to support the design and operation of offshore wind turbines.
    This experiment was conducted in collaboration with Senior Graduate Student Chiu-Chueh Sheng. Due to this cooperative relationship, some data may overlap with his research. The analysis methods and design programs used in this study were jointly developed by Professor Shen-Haw Ju’s research team. These programs and research findings are public resources. Both Professor Shen-Haw Ju and the author of this paper have the right to publish their work independently.

    摘要 I Abstract II Acknowledgment IV Contents V List of Tables VIII List of Figures IX List of Symbols XII Chapter 1 Introduction 1 1.1 Background and Purpose 1 1.2 Literature Review 2 1.3 Overview 9 Chapter 2 Wavelength and Hydrodynamic Loads 11 2.1 Introduction 11 2.2 Calculating the Wavelength 11 2.2.1 Second-order Stokes theory 11 2.2.2 Stream Function 13 2.3 Calculating the Hydrodynamic Loads 17 2.3.2 Inertia Coefficient CM 20 2.3.3 Drag Coefficient CD 24 2.3.4 Slamming Coefficient CS 25 2.4 Calculating the Strain 26 Chapter 3 The experiment of the Wave-making 27 3.1 Introduction 27 3.2 Instruments and equipment 27 3.2.1 Experimental water tank and wave maker 27 3.2.2 Wave height meter 28 3.2.3 Steel Pipe Specimen 28 3.2.4 Strain gauge 30 3.2.5 Bridge box and receiver 31 3.3 Instrument Installation 32 3.3.1 Strain gauge location 32 3.3.2 Strain gauge wiring – full bridge 33 3.3.3 Wave height meter location 34 3.4 The steps of experiments 35 3.5 Introduction and Verification of Analysis program 45 Chapter 4 Experimental and numerical results 49 4.1 Introduction 49 4.2 Wave conditions and experimental results 49 4.3 Compare corrected and uncorrected results 54 4.4 Discussion of experimental results 57 Chapter 5 Simulation of Wind and Wave Models in an Offshore Wind Turbine 59 5.1 Introduction 59 5.2 Model of Wind Farm 59 5.2.1 Normal Wind Profile Model (NWP) 63 5.2.2 Normal Turbulence Model (NTM) 65 5.2.3 Extreme Turbulence Model (ETM) 68 5.2.4 Extreme Wind Model (EWM) 71 5.2.5 Extreme Operating Gust (EOG) 74 5.2.6 Extreme Direction Change (EDC) 76 5.2.7 Extreme Coherent Gust with Direction Change (ECD) 78 5.2.8 Extreme Wind Shear Model (EWS) 80 5.2.9 Reduced Wind Model (RWM) 83 5.3 Model of wave loads 86 5.4 Fixed vs. Floating Offshore Wind Turbines 91 5.4.1 Fixed Offshore Wind Turbine 91 5.4.2 Float Wind Turbine 93 Chapter 6 Conclusions and Future Work 97 6.1 Conclusion 97 6.2 Future Work 98 References 99 Appendix A. Share Input File of the FOWT 103 Appendix B Floating wind turbine input file 118

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