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Dual inclined perforated anti-motion plates for mitigating hydroelastic response of a VLFS under wave action

OCEAN ENGINEERING 2016年 121卷 572-591页

作者： Cheng, Yong Ji, Chunyan Zhai, Gangjun Oleg, Gaidai Jiangsu Univ Sci & Technol Sch Naval Architecture & Ocean Engn Zhenjiang 212003 Peoples R China Dalian Univ Technol Deepwater Engn Res Ctr Dalian 116024 Peoples R China Norwegian Univ Sci & Technol Ctr Ships & Ocean Struct NO-7491 Trondheim Norway

This paper investigates the hydroelastic responses of a mat-like, rectangular very large floating structure (VLFS) edged with dual horizontal/inclined perforated plates using analytic method, numerical method and experimental test. In the analytic method, the eigenfunction expansion-matching method (EEMM) for multiple domains is applied to evaluate the diffraction and radiation potentials, and then the elastic equation of motion is solved by the Rayleigh-Ritz method. In the numerical model, the modal eigenvector equation of the VLFS with some discrete Mindlin plate elements are obtained by using the finite element method (FEM), whereas the boundary element method (BEM) is applied to solve the water wave equation. The hybrid finite element method-boundary element method (FEM-BEM) solutions are further employed for more general cases including inclined perforated anti-motion plates. Both analytic and numerical solutions are also validated against a series of experimental tests. The effectiveness of dual perforated plates in reducing the deflections of VLFS, is systematically assessed for various wave and plate parameters, and the performance of the anti-motion device can be significantly improved by selecting the proper design parameters. Based on the selected optimal parameters, the response reduction of VLFS with different locations of lower perforated plate is further highlighted. (C) 2016 Elsevier Ltd. All rights reserved.

关键词： Very large floating structure (VLFS) hydroelastic response Dual perforated anti-motion plates Eigenfunction expansion-matching method Experiment

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Experimental and numerical investigation of hydroelastic response of a flexible hydrofoil in cavitating flow

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INTERNATIONAL JOURNAL OF MULTIPHASE FLOW 2015年 74卷 19-33页

作者： Wu, Qin Huang, Biao Wang, Guoyu Gao, Yuan Beijing Inst Technol Sch Mech & Vechicular Engn Beijing 100081 Peoples R China

The objective of this paper is to investigate the hydroelastic response of a flexible NACA66 hydrofoil in cavitating flows by combined experimental and numerical studies. Experimental results are presented for rigid/flexible NACA66 hydrofoils fixed at alpha(0) = 80 degrees for subcavitating (sigma = 8.0) and cavitating flows (sigma = 1.4). The high-speed video camera and Laser Doppler Vibrometer are applied to investigate the flow patterns and vibration characteristics. The multiphase flow is modeled with the incompressible and unsteady Reynolds Averaged Navier-Stokes (URANS) equations. The k - omega SST turbulence model with the turbulence viscosity correction and the Zwart cavitation model are introduced to the present simulations. The results showed that the cavitation has significant effect on the foil deformation and the unsteady characteristics of the hydroelastic response. The bending deformation is enhanced when the cavitation occurred. Meanwhile, the hydroelastic response has also affected the cavitation development and the vortex structure interactions. The cavity shedding frequency and vortex shedding and interacting frequency for the flexible hydrofoil are higher than that for the rigid hydrofoil. Compared to the periodic development of the hydrodynamic coefficients for the rigid hydrofoil, the hydrodynamic load coefficients of the flexible hydrofoil fluctuate more significantly, and the chaotic response of the flexible hydrofoil is mainly attributed to the disturbance caused by the flow-induced flutter and deformation of the foil. The evolution of the transient cavity shape and the corresponding hydrodynamic response can be divided into three stages: During the development of the attached cavity, the partial sheet cavity is formed and develops with the lift and drag coefficients increasing, while the maximum attached cavity formed on the suction side of the flexible hydrofoil is larger than that of the rigid hydrofoil, which is caused by the increase of

关键词： Cavitation Cavity shedding Vortex structures Flexible hydrofoil hydroelastic response

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Load-dependent bend-twist coupling effects on the steady-state hydroelastic response of composite hydrofoils

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COMPOSITE STRUCTURES 2018年 189卷 398-418页

作者： Young, Yin L. Garg, Nitin Brandner, Paul A. Pearce, Bryce W. Butler, Daniel Clarke, David Phillips, Andrew W. Univ Michigan Dept Naval Architecture & Marine Engn Ann Arbor MI 48109 USA Univ Tasmania Australian Maritime Coll Launceston Tas 7250 Australia Def Sci & Technol Grp Maritime Div Fishermans Bend Vic 3207 Australia

The objective of this work is to present combined experimental and numerical studies of load-dependent bend-twist coupling effects on the steady-state hydroelastic response of composite hydrofoils. Experimental studies are presented for three composite and one stainless steel hydrofoils, all with the same unloaded geometry and mounted in the same cantilevered configuration. The stainless steel hydrofoil serves as the rigid baseline. The three composite hydrofoils are all made of epoxy resin reinforced with the same nominal layup of carbon fiber reinforced polymers and glass fiber reinforced polymers, with the primary difference being the orientation of the structural carbon layers relative to the spanwise axis of the hydrofoils. To compliment the experimental studies, a simple two-degrees of freedom fluid-structure interaction model is presented. The results show that material bend-twist coupling that leads to nose-up twist will experience higher hydrodynamic load coefficients, accelerated stall and static divergence, while the opposite is true for material bend-twist coupling that leads to nose-down twist. The non-dimensional hydrodynamic load coefficients for all four hydrofoils can be collapsed into the same trend line using the effective incidence, which is the geometric incidence plus the generalized tip twist angle. The results show good agreement between the experimental measurements and numerical predictions.

关键词： Fluid-structure interaction Bend-twist coupling hydroelastic response Static divergence Composite hydrofoil Experimental Numerical

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Influence of hinged conditions on the hydroelastic response of compound floating structures

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OCEAN ENGINEERING 2015年 101卷 12-24页

作者： Zhao, Cunbao Hao, Xiaochen Liang, Ruifen Lu, Jiuxi Shijiazhuang Tiedao Univ Traff Res Inst Natl Def Shijiazhuang 050043 Peoples R China

Based on the Mindlin plate theory and Wiener-Hopf technique, a solution for hydroelastic responses of 2D floating plates with hinge connection is presented under the action of different periods of monochromatic incident waves on a fluid of finite depth. The flow is assumed to be irrotational and unbounded. The floating structure is simplified as an isotropic elastic floating plate. The joints between two modules, such as the condition of the weld joint and hinged connection, are simplified as torsion springs with different torsional stiffness. The aim of solution is mainly against the velocity potential of the potential flow. According to the boundary conditions of various regions in the flow field, the mixed problems of boundary conditions and higher-order derivative are effectively solved by the Wiener-Hopf technique. Furthermore, the problems of a system of integral equations of fluid-structure interaction are deduced, which can be further simplified to a set of linear algebraic equations in the complex domain. The effects of hinged conditions on the hydroelastic response of compound floating structures, including their displacement and bending moments, are studied to provide information regarding the optimal design of such structures. (C) 2015 Elsevier Ltd. All rights reserved.

关键词： Very large compound floating structures Hinged conditions hydroelastic response Mindlin thick plate theory Wiener-Hopf technique Analytical solution

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Two-mode WEC-type attachment for wave energy extraction and reduction of hydroelastic response of pontoon-type VLFS

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OCEAN ENGINEERING 2020年 197卷

作者： Nguyen, H. P. Wang, C. M. Luong, V. H. Univ Queensland Sch Civil Engn St Lucia Qld 4072 Australia Vietnam Natl Univ Ho Chi Minh City Ho Chi Minh City Univ Technol Dept Civil Engn Ho Chi Minh City Vietnam

Proposed herein is a two-mode wave energy converter-type attachment to the fore edge of pontoon-type very large floating structures (VLFSs) for wave energy extraction and reduction of hydroelastic response. This attachment consists of floating horizontal and submerged vertical plates that are connected to the VLFS with hinges and linear power take-off systems. The use of both floating horizontal and submerged vertical plates combines the superior performances of floating plates in extracting wave energy from short waves (T < 5 s) and of submerged vertical plates in extracting wave energy from intermediate and long waves (T > 7 s). When deployed in sites where 5 s <= T <= 7 s, the two-mode attachment yields a larger power production than the sole usage of floating plates or the sole usage of submerged vertical plates. Interestingly, the two-mode attachment also combines the superior performance of submerged vertical plates in reducing hydroelastic response for relatively short waves (T <= 7 s) and the superior performance of floating plates in reducing hydroelastic response for relatively long waves (T >= 9 s). Moreover, this two-mode attachment furnishes a good balance between extracting wave energy and reducing hydroelastic response of VLFS for the same wave period.

关键词： Very large floating structure hydroelastic response Raft wave energy converter Oscillating wave surge converter

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Optimization of modular raft WEC-type attachment to VLFS and module connections for maximum reduction in hydroelastic response and wave energy production

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OCEAN ENGINEERING 2019年 172卷 407-421页

作者： Nguyen, H. P. Wang, C. M. Pedroso, D. M. Univ Queensland Sch Civil Engn St Lucia Qld 4072 Australia

This paper presents optimization of modular raft WEC-type attachment to VLFS and connections between floating modules of the VLFS for regular and irregular waves. The modular raft WEC-type attachment consists of multiple independent auxiliary pontoons connected to the fore edge of the VLFS with hinges and linear Power Take-Off (PTO) systems. The two objectives of the optimization are to maximize the reduction in hydroelastic response of VLFS and the power capture factor. The optimization process is proposed by using differential evolution (DE) algorithm. A numerical analysis framework based on finite element-boundary element (FE-BE) method is presented for determining the power capture factor as well as the hydroelastic response reduction for regular and irregular waves. The proposed optimization process is used to investigate the effects of the design variables, including PTO damping coefficient, pontoon length, the number of connections and connection stiffness, on the trade-off curve (i.e. Pareto front). In addition, the maximum power capture factor and hydro elastic response reduction are examined for various regular and irregular waves.

关键词： Very large floating structure (VLFS) Wave energy converter (WEC) hydroelastic response Connection design Multi-objective optimization Differential evolution (DE)

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A Study on hydroelastic response of Box-Type Very Large Floating Structures

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China Ocean Engineering 2001年第3期16卷 345-354页

作者：王志军李润培舒志 School of Naval Architecture and Ocean Engineering Shanghai Jiao Tong University

The application of very large floating structure (VLFS) to the utilization of ocean space and exploitation of ocean resources has become one of the issues of great interest in international ocean engineering field. Owing to the advantage of simplicity in structure and low cost of construction and maintenance, box-type VLFS can be used in the calm water area near the coast as the structure configuration of floating airport. In this paper, a 3D linear hydroelastic theory is used to study the dynamic response of box-type VLFS in sinusoidal regular waves. A beam model and a 3D FEM model are respectively employed to describe the dynamic characteristics of the box-type Structure in vacuum. A hydrodynamic model (3D potential theory of flexible body) is applied to investigate the effect of different dry models on the hydroelastic response of box-type structure. Based on the calculation of hydroelastic response in regular waves, the rigid body motion displacement, flexible deflection, and the short term and long term wave induced bending moments are also predicted.

关键词： box-type VLFS hydroelastic response dry structure short term prediction long tern prediction

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Experimental and numerical investigation on the hydroelastic response of barge and KVLCC2 ship

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OCEAN ENGINEERING 2024年 307卷

作者： Xie, Binyang He, Guanghua Zhao, Chuankai Jing, Penglin Pal, Sumit Kumar Iijima, Kazuhiro Jin, Ruijia Chen, Bangqi Ghassemi, Hassan Harbin Inst Technol Dept Naval Architecture & Ocean Engn Weihai Peoples R China Osaka Univ Dept Naval Architecture & Ocean Engn Osaka Japan Delft Univ Technol Dept Aerosp Engn Kluyverweg 1 NL-2629 HS Delft Netherlands MOT Tianjin Res Inst Water Transport Engn Tianjin 300456 Peoples R China

In this paper, the hydroelasticity of two segmented ship models (Barge and KVLCC2) is investigated by experimental and numerical methods. A two-way Computational Fluid Dynamics (CFD) and Finite Element Analysis (FEA) coupled method is adopted and further validated its accuracy against experimental results. The current approach emphasizes the overall convergence between two solvers, maintaining a strongly coupled manner to comprehensively address the fluid-structure interaction phenomenon, including the added mass effect. A series of experiments of a segmented Barge and KVLCC2 under various wave conditions were firstly conducted. The motions of the models are measured and the displacement response Amplitude Operators (RAOs) are calculated. The CFD-FEA coupled method is demonstrated in agreement with experimental results by comparing the numerical prediction with the tank test results in terms of motion, affirming the validity and robustness. Finally, the hydroelastic response is discussed and investigated.

关键词： Segmented barge ship KVLCC2 ship hydroelastic response CFD-FEA coupled method

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Transient hydroelastic response of VLFS by FEM with Impedance Boundary Conditions in Time Domain

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China Ocean Engineering 2005年第1期19卷 1-9页

作者：邱流潮刘桦 Department of Engineering Mechanics Shanghai Jiao Tong UniversityShanghai 200030 China

A time-dependent finite element method (FEM) is developed to analyze the transient hydroelastic responses of very large floating structures (VLFS) subjected to dynamic loads. The hydrodynamic problem is formulated based on the linear theory of fluid and the structural response is analyzed based on the thin plate theory. The FEM truncates the unbounded fluid domain by introducing an artificial boundary surface, thus defining a finite computational domain. At this boundary surface an impedance boundary conditions are applied so that no wave reflections occur. In the proposed scheme, all of the procedures are processed directly in time domain, which is efficient for nonlinear analyses of structure floating on unbounded fluid. Numerical results indicate acceptable accuracy of the proposed method.

关键词： very large floating structure hydroelastic response impedance boundary conditions transient response fluid-structure interactions finite element method

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Power enhancement of pontoon-type wave energy convertor via hydroelastic response and variable power take-off system

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Journal of Ocean Engineering and Science 2020年第1期5卷 1-18页

作者： Zhi Yung Tay Yanji Wei Engineering Cluster Singapore Institute of Technology10 Dover DriveSingapore 138683Singapore Faculty of Science and Engineering University of GroningenNijenborgh 4Groningen 9747AGthe Netherlands

Wave energy has gained its popularity in recent decades due to the vast amount of untapped wave energy *** are numerous types of wave energy convertor(WEC)being proposed and to be economically viable,various means to enhance the power generation from WECs have been studied and *** this paper,a novel pontoon-type WEC,which is formed by multiple plate-like modules connected by hinges,are *** power enhancement of this pontoon-type WEC is achieved by allowing certain level of structural deformation and by utilizing a series of optimal variable power take-off(PTO)*** wave energy is converted into useful electricity by attaching the PTO systems on the hinge connectors such that the mechanical movements of the hinges could produce *** this paper,various structural rigidity of the interconnected modules are considered by changing the material Young’s modulus in order to investigate its impact on the power *** addition,the genetic algorithm optimization scheme is utilized to seek for the optimal PTO damping in the variable PTO *** is observed that under certain condition,the flexible pontoon-type WEC with lesser connection joints is more effective in generating energy as compared to its rigid counterpart with higher connection *** is also found that the variable PTO system is able to generate greater energy as compared to the PTO system with constant/uniform PTO damping.

关键词： Power generation enhancement Pontoon-type wave energy convertor Very large floating structure(VLFS) hydroelastic response Variable power take-off system Genetic algorithm optimization.

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