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Coupled dynamic response analysis of multi-column floating offshore wind turbine with low center of gravity

Journal of Ocean Engineering and Science 2024年第1期9卷 25-39页

作者： Jie Yang Yan-ping He Yong-sheng Zhao Xiao-yan Yang Guo-rong Zhang State Key Laboratory of Ocean Engineering Shanghai Jiao Tong UniversityShanghai 200240China collaborative innovation center for advanced ship and Deep-Sea exploration(CISSE) Shanghai Jiao Tong UniversityShanghai 200240China School of Naval Architecture Ocean&Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China Faculty of Maritime and Transportation Ningbo UniversityNingbo 315211China

To realize the application of the floating offshore wind turbine(FOWT)from deep to relatively shallow waters,a new concept of multi-column floating wind turbine platform with low center of gravity(CG)is designed and *** multi-column low CG platform is designed to support a 6MW wind turbine class and operated at a water depth of 50m in the South China *** frequency domain software WADAM and time domain software NREL-FAST are used to simulate coupled dynamic responses of the floating wind turbine system with second-order wave loads *** dynamic behaviors of multi-column low CG FOWT system under normal operation and parked conditions are *** influence of second-order wave force on the motion responses of the multi-column platform,fore-aft force and moment of the tower base and mooring force are researched *** results demonstrate that the coupled dynamic responses at rated operating condition and extreme condition meet the normal operating requirements and extreme survival requirements of FOWT system in the shallow water(50m)of South China *** addition,it is found that,the wave frequency response gradually replaces the second-order low frequency response as the main influencing factor of the coupled dynamic response of the FOWT system with the increasing severity of the sea ***,in general,the magnitude of second-order low frequency response increases with the increasing severity of the design load ***,in the subsequent design of the shallow water FOWT system,the second-order effects should be paid enough attention.

关键词： Floating offshore wind turbine Multi-column platform Second-order wave force Concept design Coupled dynamic response

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爆破型和聚能型装药水下爆炸载荷特性

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哈尔滨工程大学学报（英文版） 2024年第2期23卷 302-315页

作者：张之凡李海龙张竞元王龙侃张桂勇宗智 State Key Laboratory of Structural Analysis Optimization and CAE Software for Industrial EquipmentSchool of Naval Architecture EngineeringDalian University of TechnologyDalian 116024China China ship Research and Development Academy Beijing 100192China collaborative innovation center for advanced ship and Deep-Sea exploration Shanghai 200240China

Blasting and shaped charges are the main forms of underwater weapons,and their near-field underwater explosions(UNDEX)can severely damage ***,it is of great importance to study underwater explosive load characteristics of different forms of *** full physical process of a typical underwater explosion of a sphere/column blasting charge and a shaped charge was simulated using the Eulerian *** loading characteristics of the underwater blast shock wave and bubble,as well as the projectile,were *** results show that the shock wave loads of spherical,cylindrical,and polygonal charges propagate outward in spherical,ellipsoidal–spherical and ellipsoidal–spherical wavefronts,*** the shock wave reaches 16 times the distance-to-diameter ratio,its surface is approximately *** addition,in the shaped charge underwater explosion,the shaped charge liner cover absorbs 30°–90°of the shock wave energy and some of the bubble energy to form a high-speed shaped ***,ellipsoidal,and ellipsoidal bubbles are generated by underwater explosions of spherical,cylindrical,and shaped charges,*** obtained results provide a reference for evaluating the power of underwater weapons.

关键词： Blasting charge Shaped charge Load characteristics Shock wave Bubble

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An Improved Spectral Analysis Method for Fatigue Damage Assessment of Details in Liquid Cargo Tanks

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China Ocean Engineering 2018年第1期32卷 62-73页

作者： ZHAO Peng-yuan HUANG Xiao-ping collaborative innovation center for advanced ship and Deep-Sea exploration Shanghai Jiao Tong University

Errors will be caused in calculating the fatigue damages of details in liquid cargo tanks by using the traditional spectral analysis method which is based on linear system, for the nonlinear relationship between the dynamic stress and the ship acceleration. An improved spectral analysis method for the assessment of the fatigue damage in detail of a liquid cargo tank is proposed in this paper. Based on assumptions that the wave process can be simulated by summing the sinusoidal waves in different frequencies and the stress process can be simulated by summing the stress processes induced by these sinusoidal waves, the stress power spectral density(PSD) is calculated by expanding the stress processes induced by the sinusoidal waves into Fourier series and adding the amplitudes of each harmonic component with the same frequency. This analysis method can take the nonlinear relationship into consideration and the fatigue damage is then calculated based on the PSD of stress. Take an independent tank in an LNG carrier for example, the accuracy of the improved spectral analysis method is proved much better than that of the traditional spectral analysis method by comparing the calculated damage results with the results calculated by the time domain method. The proposed spectral analysis method is more accurate in calculating the fatigue damages in detail of ship liquid cargo tanks.

关键词： liquid cargo tank nonlinear system fatigue damage spectral analysis method dynamic pressure

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Numerical prediction of effective wake field for a submarine based on a hybrid approach and an RBF interpolation

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Journal of Hydrodynamics 2017年第4期29卷 691-701页

作者：饶志强杨晨俊 collaborative innovation center for advanced ship and Deep-Sea exploration State Key Laboratory of Ocean Engineering Shanghai Jiao Tong University

A hybrid approach coupled with a surface panel method for the propeller and a Reynolds averaged Navier-Stokes（RANS） model for the hull with the propeller body forces are presented for predicting the self-propulsion performance and the effective wake field of underwater vehicles. To achieve a high accuracy and simplicity, a radial basis function（RBF） based approach is proposed for mapping the force field from the blade surface panels to the RANS model. The effective wake field is evaluated in two ways, i.e., by extrapolation from the flat planes upstream of the propeller disk, and by direct computation in a curved surface upstream of and parallel to the blade leading edges. The hull-propeller system of a real propeller geometry is further simulated with the sliding mesh model to numerically verify the hybrid approach. Numerical simulations are conducted for the fully appended SUBOFF submarine model. The high accuracy of the RBF-based interpolation scheme is confirmed, and the effective wake fraction predicted by the hybrid approach is found consistent with that obtained by the sliding mesh model. The effective wake fractions predicted by the two methods are, respectively, 4.6% and 3% larger than the nominal one.

关键词： Submarine effective wake panel method Reynolds averaged Navier-Stokes(RANS) radial basis function(RBF)

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Dynamic Stability Analysis of Caisson Breakwater in Lifetime Considering the Annual Frequency of Severe Storm

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China Ocean Engineering 2015年第2期29卷 287-300页

作者：王禹迟王元战洪宁宁 State Key Laboratory for Simulation & Safety of Hydraulic Engineering Collaborative Innovation Center for Advanced Ship and Deep-Sea ExplorationTianjin University

In the dynamic stability analysis of a caisson breakwater, most of current studies pay attention to the motion characteristics of caisson breakwaters under a single periodical breaking wave excitation. And in the lifetime stability analysis of caisson breakwater, it is assumed that the caisson breakwater suffers storm wave excitation once annually in the design lifetime. However, the number of annual severe storm occurrence is a random variable. In this paper, a series of random waves are generated by the Wen Sheng-chang wave spectrum, and the histories of successive and long-term random wave forces are built up by using the improved Goda wave force model. It is assumed that the number of annual severe storm occurrence is in the Poisson distribution over the 50-year design lifetime, and the history of random wave excitation is generated for each storm by the wave spectrum. The response histories of the caisson breakwater to the random waves over 50-year design lifetime are calculated and taken as a set of samples. On the basis of the Monte Carlo simulation technique, a large number of samples can be obtained, and the probability assessment of the safety of the breakwater during the complete design lifetime is obtained by statistical analysis of a large number of samples. Finally, the procedure of probability assessment of the breakwater safety is illustrated by an example.

关键词： caisson breakwater dynamic stability lifetime wave spectrum annual storm frequency

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Research Progress of Buckling Propagation Experiment of Deep-Water Pipelines

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Transactions of Tianjin University 2016年第4期22卷 285-293页

作者：余建星吴梦宁孙震洲段晶辉 State Key Laboratory of Hydraulic Engineering Simulation and Safety Tianjin UniversityTianjin 300354China collaborative innovation center for advanced ship and deepsea exploration Shanghai 200240China

In recent years, the extraction of fossil resources, especially oil and gas in deep and ultra-deep water areas has been playing a more important role and been paid more attention to. For this reason, the working depth of submarine pipelines, which are used for the transportation of oil and gas, has been increasing sharply. As the main failure pattern of deep-water pipelines, buckling and its propagation problem have drawn more attention of many research institutions and engineering units around the world. Based on the existing research, the summary of experiments and their outcomes of deep-water pipeline buckling failure is made in this paper. Research status and developing prospects of the experiments of buckling propagation and buckle arrestor are discussed in detail.

关键词： deep-water pipelines buckling propagation hyperbaric chamber buckle arrestor

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Numerical Analyses of Caisson Breakwaters on Soft Foundations Under Wave Cyclic Loading

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China Ocean Engineering 2016年第1期30卷 1-18页

作者：王元战焉振王禹迟 National Key Laboratory of Water Conservancy Engineering Simulation and Security Collaborative Innovation Center for Advanced Ship and Deep-Sea ExplorationTianjin University

A caisson breakwater is built on soft foundations after replacing the upper soft layer with sand. This paper presents a dynamic finite element method to investigate the strength degradation and associated pore pressure development of the intercalated soft layer under wave cyclic loading. By combining the undrained shear strength with the empirical formula of overconsolidation clay produced by unloading and the development model of pore pressure, the dynamic degradation law that describes the undrained shear strength as a function of cycle number and stress level is derived. Based on the proposed dynamic degradation law and M-C yield criterion, a dynamic finite element method is numerically implemented to predict changes in undrained shear strength of the intercalated soft layer by using the general-purpose FEM software ABAQUS, and the accuracy of the method is verified. The effects of cycle number and amplitude of the wave force on the degradation of the undrained shear strength of the intercalated soft layer and the associated excess pore pressure response are investigated by analyzing an overall distribution and three typical sections underneath the breakwater. By comparing the undrained shear strength distributions obtained by the static method and the quasi-static method with the undrained shear strength distributions obtained by the dynamic finite element method in the three typical sections, the superiority of the dynamic finite element method in predicting changes in undrained shear strength is demonstrated.

关键词： soft layer strength degradation pore pressure development wave cyclic loading dynamic finite element method

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Modeling of bistatic scattering from an underwater non-penetrable target using a Kirchhoff approximation method

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Defence Technology（防务技术） 2022年第7期18卷 1097-1106页

作者： Bin Wang Wen-huan Wang Jun Fan Kai-qi Zhao Fu-lin Zhou Li-wen Tan collaborative innovation center for advanced ship and Deep-Sea exploration State Key Laboratory of Ocean EngineeringShanghai Jiao Tong UniversityShanghai200240China

A numerical triangulation and transformation into the time domain of a Kirchhoff approximation(KA)method is proposed for the modeling of bistatic scattering from an underwater non-penetrable *** time domain solution in this approximation can be split up into two parts:the solution of reflected field,contributing around the specular direction,and the solution of shadow radiation,contributing around the forward *** average solution in the time domain satisfying the reciprocity principle is *** solution is expressed in terms of non-singular *** proposed method is validated against a normal mode method for bistatic scattering from a rigid ***,the reflected and shadow highlights on the surface of the sphere are shown to verify the integration surface of the reflected field and shadow *** is also tested against a finite element method and an experiment involving a scaled Benchmark Target Strength Simulation Submarine *** time-angle bistatic spectra for the model are evaluated by the direct and transformed average solutions of KA,and the former accelerates its speed of *** results are good,and show that this method can be used to predict the bistatic scattered field of a non-penetrable target.

关键词： Kirchhoff approximation Bistatic scattering Time domain Reciprocity Experiment

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Effect of Annealing on Microstructure and Mechanical Properties of Ultrafine-Grained Low-Carbon Medium-Manganese Steel Produced by Heavy Warm Rolling

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Acta Metallurgica Sinica(English Letters) 2019年第3期32卷 361-371页

作者： Sohail Ahmad Li-Feng Lv Li-Ming Fu Huan-Rong Wang Wei Wang Ai-Dang Shan School of Materials Science and Engineering Shanghai Jiao Tong University collaborative innovation center for advanced ship and Deep-Sea exploration(CISSE) Baosteel Research Institute

An ultrafine-grained(UFG) low-carbon medium-manganese steel was fabricated by the heavily warm rolling(HWR) and subsequent quenching, and the effects of annealing temperatures on microstructure and mechanical properties of the UFG HWRed steel were investigated. The results show that the HWRed steel exhibits simultaneous improvements in strength,uniform elongation and work hardening, which is mainly attributed to the refinement of martensitic microstructures. The HWRed steels comprise only a-phase when annealing at lower temperatures below to 550 °C and at higher temperatures above to 700 °C. Whereas, UFG c-austenite is formed by reverse transformation when the HWRed steel was annealed at intermediate temperatures from 550 to 700 °C and the volume fraction increases with increasing annealing temperatures,consequently resulting in a dramatic increase in ductility of the annealed HWRed steels. It was found that the transformed UFG austenite and ferrite remained ～500 nm and ～800 nm in size when the HWRed steel was annealed at 650 and700 °C for 1 h, respectively, showing an excellent thermal stability. Moreover, the HWRed steel annealed at 650 °C exhibits high strength-ductility combinations with a yield strength of 906 MPa, ultimate tensile strength(UTS) of1011 MPa, total elongation(TEL) of 51% and product of strength and elongation(PSE: UTS 9 TEL) of 52 GPa%. It is believed that these excellent comprehensive mechanical properties are closely associated with the UFG austenite formation by reverse transformation and principally attributed to the transformation-induced plasticity(TRIP) effect.

关键词： Ultrafine-grained medium-Mn steel Heavy warm rolling Annealing Microstructure and properties Transformation-induced plasticity(TRIP) effect

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Experimental, Numerical and Simplified Theoretical Model Study for Internal Solitary Wave Load on FPSO with Emphasis on Scale Effect

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China Ocean Engineering 2019年第1期33卷 26-33页

作者： ZHANG Rui-rui CHEN Ke YOU Yun-xiang State Key Laboratory of Ocean Engineering Shanghai Jiao Tong University collaborative innovation center for advanced ship and Deep-Sea exploration Jiangsu University of Science and Technology

Scale effect of ISWs loads on Floating Production Storage and Offloading(FPSO) is studied in this paper. The application conditions of KdV, eKdV and MCC ISWs theories are used in the numerical method. The depthaveraged velocities induced by ISWs are used for the velocity-inlet boundary. Three scale ratio numerical models λ=1, 20 and 300 were selected, which the scale ratio is the size ratio of numerical models to the experimental *** comparisons between the numerical and former experimental results are performed to verify the feasibility of numerical method. The comparisons between the numerical and simplified theoretical results are performed to discuss the applicability of the simplified theoretical model summarized from the load experiments. Firstly, the numerical results of λ=1 numerical model showed a good agreement with former experimental and simplified theoretical results. It is feasible to simulate the ISWs loads on FPSO by the numerical method. Secondly, the comparisons between the results of three scale ratio numerical models and experimental results indicated that the scale ratios have more significant influence on the experimental horizontal forces than the vertical forces. The scale effect of horizontal forces mainly results from the different viscosity effects associated with the model’s ***, through the comparisons between the numerical and simplified theoretical results for three scale ratio models, the simplified theoretical model of the pressure difference and friction forces exerted by ISWs on FPSO is applied for large-scale or full-scale FPSO.

关键词： scale effect FPSO internal solitary wave numerical simulation simplified theoretical model

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