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Numerical Simulation of Icing on Nrel 5-MW Reference offshore wind turbine Blades Under Different Icing Conditions

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China Ocean Engineering 2022年第5期36卷 767-780页

作者： CAO Hui-qing BAI Xu MA Xian-dong YIN Qun YANG Xiang-yu School of Naval Architecture&Ocean Engineering Jiangsu University of Science and TechnologyZhenjiang 212003China The Department of Engineering Lancaster UniversityLancaster LA14YWUK

offshore wind energy resources are operational in cold regions,while offshore wind turbines will face the threat of ***,it is necessary to study icing of offshore wind turbines under different icing *** this study,icing sensitivity of offshore wind turbine blades are performed using a combination of FLUENT and FENSAP-ICE software,and the effects of liquid water content(LWC),medium volume diameter(MVD),wind speed and air temperature on blade icing shape are analyzed by two types of ice,namely rime ice and glaze *** results show that the increase of LWC and MVD will increase the amount of ice that forms on the blade surface for either glaze ice or rime ice,and an increase of MVD will expand the adhesion surface between ice and *** reaching the rated wind speed of 11.4 m/s,it does not directly affect the icing ***,after reaching the rated wind speed,the attack angle of the incoming flow decreases obviously,and the amount of ice increases *** the ambient air temperature meets the icing conditions of glaze ice(i.e.,−5℃ to 0℃),the lower the temperature,the more glaze ice freezes,whereas air temperature has no impact on the icing of rime *** with onshore wind turbines,offshore wind turbines might face extreme meteorological conditions,and the wind speed has no impact on the amount of ice that forms on the blade surface for most wind speeds.

关键词： environmental parameters cold regions offshore wind turbine rime glaze numerical simulation

A brief discussion on offshore wind turbine hydrodynamics problem

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Journal of Hydrodynamics 2022年第1期34卷 15-30页

作者： Zhi-teng Gao Xing-ya Feng Zi-tan Zhang Zheng-liang Liu Xiao-xia Gao Li-jun Zhang Shan Li Ye Li Multi-function Towing Tank School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai200240China Department of Ocean Science and Engineering Southern University of Science and TechnologyShenzhen518055China Hebei key Laboratory of Low Carbon and High Efficiency Power Generation Technology Department of Power EngineeringNorth China Electric Power UniversityBaoding071003China

Recently, offshore renewable energy has received significant attentions from most oceanic countries. Its multiple disciplinary nature appears as a hot research spot. Among those resources, offshore wind has been experiencing a rapid growth with strong industrial and governmental support. Among the research topics related to offshore wind turbine, those related to efficiency and safety issue receive most attentions, and they cover hydrodynamics, aerodynamics, structural dynamics, elasticity and so on. Hydrodynamics is considered as the key of these research for offshore wind turbine. This is not only because it is the fundamental of ocean engineering, but also it is similar to low speed aerodynamics which is the key of wind turbine rotor. In order to provide a comprehensive understanding of the important problems of offshore wind turbine hydrodynamics, we briefly review the evolution of offshore wind turbine and discuss the hydrodynamics problem associated with the research and development activities.

关键词： offshore renewable energy offshore wind turbine hydrodynamics low speed aerodynamics aero-hydro dynamics coupling

Simulation of offshore wind turbine Blade Docking Based on the Stewart Platform

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Energy Engineering 2023年第11期120卷 2489-2502页

作者： Yi Zhang Jiamin Guo Huanghua Peng College of Ocean Science and Engineering Shanghai Maritime UniversityShanghai201306China

The windy environment is the main cause affecting the efficiency of offshore wind turbine *** order to improve the stability and efficiency of single-blade installation of offshore wind turbines under high wind speed conditions,the Stewart platform is used as an auxiliary tool to help dock the wind turbine blade in this *** order to verify the effectiveness of the Stewart platform for blade docking,a blade docking simulation system consisting of the Stewart platform,wind turbine blade,and wind load calculation module was built based on Simulink/*** the same time,the PID algorithm is used to control the Stewart platform so that the blade can effectively track the desired trajectory during the docking process to ensure the successful docking of the *** the simulation of the docking process for blades with a length of 61.5 meters,this paper successfully demonstrates a docking system that might facilitate future docking *** also shows that the Stewart platform can effectively reduce the vibration and the movement range of the blade root and improve the stability and efficiency of blade docking.

关键词： offshore wind turbine Stewart platform blade docking PID simscape multibody

Experimental Study on Tilt Adjustment Technique of Tripod Bucket Jacket Foundation for offshore wind turbine in Sand

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Journal of Marine Science and Application 2022年第4期21卷 192-204页

作者： Puyang Zhang Yuxuan Ma Conghuan Le Hongyan Ding State Key Laboratory of Hydraulic Engineering Simulation and Safety Tianjin UniversityTianjin 300072China School of Civil Engineering Tianjin UniversityTianjin 300072China

For the tripod bucket jacket foundations used in offshore wind turbines, the probable critical tilt angles should be avoidedduring tilt adjustment operation. Thus, these critical values must be identified by engineers, and remedial techniques mustbe established prior to the occurrence of the problem. Model tests were carried out for typical tilting conditions of tripodbucket foundations, which were allowed to tilt freely at various penetration depths without interruption by manualoperation. After the foundation ceased its tilting, some measures, such as water pumping, water injection, air injection, or acombination of the above methods, were enabled for adjustment. The research results showed two critical values in thetilting state of the tripod bucket jacket foundation, namely the terminal and allowable angles. In the installation condition,the terminal angle was negatively correlated with the initial penetration depth, but the opposite was observed with theremoval condition. The allowable angle was less than or equal to the terminal angle. The allowable angle in the installationwas related to the terminal angle. The critical angles all varied linearly with the initial penetration depth. When tiltingduring installation, adjustment measures can be used in the order of high drum pumping, low drum water injection, highdrum pumping and low drum water injection, air injection, and exhaust. When tilting during removal, the sequential use oflow drum water injection, air, and exhaust was applied. For buckets that were sensitive to angle changes, adjustmentmeasures of the “point injection” mode can be selected.

关键词： Tripod bucket jacket foundation Tilt adjustment Penetration and removal Terminal angle Allowable angle offshore wind turbine

Shaking table test and numerical analysis of offshore wind turbine tower systems controlled by TLCD

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Earthquake Engineering and Engineering Vibration 2015年第1期14卷 55-75页

作者： Chen Jianbing Liu Youkun Bai Xueyuan State Key Laboratory of Disaster Reduction in Civil Engineering & School of Civil Engineering Tongji University Shanghai Electric Power Design Institute Co. Ltd Jiang Architects & Engineers

A wind turbine system equipped with a tuned liquid column damper （TLCD） is comprehensively studied via shaking table tests using a 1/13-scaled model. The effects of wind and wave actions are considered by inputting response- equivalent accelerations on the shaking table. The test results show that the control effect of the TLCD system is significant in reducing the responses under both wind-wave equivalent loads and ground motions, but obviously varies for different inputs, Further, a blade-hub-tower integrated numerical model for the wind turbine system is established. The model is capable of considering the rotational effect of blades by combining Kane＇s equation with the finite element method. The responses of the wind tower equipped with TLCD devices are numerically obtained and compared to the test results, showing that under both controlled and uncontrolled conditions with and without blades＇ rotation, the corresponding responses exhibit good agreement. This demonstrates that the proposed numerical model performs well in capturing the wind-wave coupled response of the offshore wind turbine systems under control. Both numerical and experimental results show that the TLCD system can significantly reduce the structural response and thus improve the safety and serviceability of the offshore wind turbine tower systems. Additional issues that require further study are discussed.

关键词： offshore wind turbine shaking table test TLCD numerical model vibration control

A simplified method for analyzing the fundamental frequency of monopile supported offshore wind turbine system design

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Earthquake Engineering and Engineering Vibration 2018年第4期17卷 893-901页

作者： Yang Chunbao Wang Rui Zhang Jianmin School of Civil Engineering/State Key Laboratory of Hydroscience and Engineering Department of Hydraulic Engineering Tsinghua University

Preliminary design of offshore wind turbines requires high precision simplified methods for the analysis of the system fundamental frequency. Based on the Rayleigh method and Lagrange’s Equation, this study establishes a simple formula for the analysis of system fundamental frequency in the preliminary design of an offshore wind turbine with a monopile foundation. This method takes into consideration the variation of cross-section geometry of the wind turbine tower along its length, with the inertia moment and distributed mass both changing with diameter. Also the rotational flexibility of the monopile foundation is mainly considered. The rigid pile and elastic middle long pile are calculated separately. The method is validated against both FEM analysis cases and field measurements, showing good agreement. The method is then used in a parametric study, showing that the tower length Lt, tower base diameter d0, tower wall thickness δt, pile diameter db and pile length Lb are the major factors influencing the fundamental frequency of the offshore wind turbine system. In the design of offshore wind turbine systems, these five parameters should be adjusted comprehensively. The seabed soil condition also needs to be carefully considered for soft clay and loose sand.

关键词： offshore wind turbine system fundamental frequency analytical method rotational foundation flexibility

Dynamic Analysis of Tension Leg Platform for offshore wind turbine Support as Fluid-Structure Interaction

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China Ocean Engineering 2011年第1期25卷 123-131页

作者：黄虎张社荣 North China University of Water Resources and Electric Power College of Civil Engineering Tianjin University

Tension leg platform （TLP） for offshore wind turbine support is a new type structure in wind energy utilization. The strong-interaction method is used in analyzing the coupled model, and the dynamic characteristics of the TLP for offshore wind turbine support are recognized. As shown by the calculated results： for the lower modes, the shapes are water＇s vibration, and the vibration of water induces the structure＇s swing; the mode shapes of the structure are complex, and can largely change among different members; the mode shapes of the platform are related to the tower＇s. The frequencies of the structure do not change much after adjusting the length of the tension cables and the depth of the platform; the TLP has good adaptability for the water depths and the environment loads. The change of the size and parameters of TLP can improve the dynamic characteristics, which can reduce the vibration of the TLP caused by the loads. Through the vibration analysis, the natural vibration frequencies of TLP can be distinguished from the frequencies of condition loads, and thus the resonance vibration can be avoided, therefore the offshore wind turbine can work normally in the complex conditions.

关键词： offshore wind turbine tension leg platform fluid structure interaction dynamic characteristics yaw resonance vibration

Gravity Effect on the First Natural Frequency of offshore wind turbine Structures

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Transactions of Nanjing University of Aeronautics and Astronautics 2016年第1期33卷 95-101页

作者： Ma Hongwang Chen Longzhu Department of Civil Engineering Shanghai Jiao Tong University

The fatigue limit state is critical for most offshore wind *** minimize the development of fatigue damage,dynamic amplification of the response must be ***,it is important to ensure that the first natural frequency of the offshore wind turbine does not coincide with the excitation frequencies related to wind turbine and wave *** evaluating the self-gravity influence on the first natural frequency of wind turbine support structures,the offshore wind turbine system vibration is modeled using an Euler-Bernoulli beam with axial force and horizontal *** data from five wind turbines available in the market are *** sizes of wind turbines vary from 2.3MW to 6MW,and subsequently,the heights of tubular steel towers vary from 83 mto *** indicate that the average influence of gravity on the first natural frequency is nearly 1.8%.The first natural frequency is considered ranging from 1P(rototor frequency)to 3P(blade passing frequency).The design procedure requires an accurate evaluation of the first natural *** this perspective,the first natural frequency is reduced since gravity needs to be considered for the design of offshore wind turbine support structures,especially when the first natural frequency of the offshore wind turbine is close to the lower limit,rotor frequency1 P.

关键词： offshore wind turbine the first natural frequency gravity Euler-Bernoulli beam

Probabilistic Response and Short-Term Extreme Load Estimation of offshore Monopile wind turbine Towers by Probability Density Evolution Method

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China Ocean Engineering 2022年第3期36卷 363-371页

作者： ZHANG Hui XU Ya-zhou School of Building Services Science and Engineering Xi’an University of Architecture and TechnologyXi’an 710055China School of Civil Engineering Xi’an University of Architecture and TechnologyXi’an 710055China

A new analysis framework based on probability density evolution method(PDEM)and its Chebyshev collocation solution are introduced to predict the dynamic response and short-term extreme load of offshore wind turbine(OWT)towers subjected to random sea *** regard to the stochastic responses,random function method is employed to generate samples of sea elevation,the probability density evolution equation(PDEE)is solved to calculate time-variant probability density functions of structural *** the probabilistic load estimation,a FAST model of NREL 5MW offshore turbine is established to obtain samples of bending moment at the tower *** equivalent extreme event theory is used to construct a virtual stochastic process(VSP)to assess the short-term extreme *** results indicate that the proposed approach can predict time-variant probability density functions of the structural responses,and shows good agreement with Monte Carlo ***,the predicted short-term extreme load can capture the fluctuation at the tail of the extreme value distribution,thus is more rational than results from the typical distribution ***,the proposed method shows good adaptation,precision and efficiency for the dynamic response analysis and load estimation of OWT towers.

关键词： offshore wind turbine probability density evolution method Chebyshev collocation matrix exponential Monte Carlo