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Effect of Mass Ratio on Hydrodynamic Response of a Flexible Cylinder
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作者 Haoyang Cen Rupp Carriveau David S-K Ting 《Journal of Marine Science and Application》 CSCD 2016年第1期50-62,共13页
The effect of the mass ratio on the flow-induced vibration (FIV) of a flexible circular cylinder is experimentally investigated in a towing tank. A Tygon tube with outer and inner diameters of 7.9 mm and 4.8 mm, res... The effect of the mass ratio on the flow-induced vibration (FIV) of a flexible circular cylinder is experimentally investigated in a towing tank. A Tygon tube with outer and inner diameters of 7.9 mm and 4.8 mm, respectively, was employed for the study. The tube was connected to a carriage and towed from rest to a steady speed up to 1.6 m/s before slowing down to rest again over a distance of 1.6 m in still water. Reynolds number based on the cylinder's outer diameter was 800-13,000, and the reduced velocity (velocity normalized by the cylinder's natural frequency and outer diameter) spanned from 2 to 25. When connected, the cylinder was elongated from 420 mm to 460 mm under an axial pre-tension of 11 N. Based on the cylinder's elongated length, the aspect ratio (ratio of the cylinder's length to outer diameter) was calculated as 58. Three mass ratios (ratio of the cylinder's structural mass to displaced fluid mass, m*) of 0.7, 1.0, and 3.4 were determined by filling the cylinder's interior with air, water, and alloy powder (nickel-chromium-boron matrix alloy), respectively. An optical method was adopted for response measurements. Multi-frequency vibrations were observed in both in-line (IL) and cross-flow (CF) responses; at high Reynolds number, vibration modes up to the 3rd one were identified in the CF response. The mode transition was found to occur at a lower reduced velocity for the highest tested mass ratio. The vibration amplitude and frequency were quantified and expressed with respect to the reduced velocity. A significant reduced vibration amplitude was found in the IL response with increasing mass ratios, and only initial and upper branches existed in the IL and CF response amplitudes. The normalized response frequencies were revealed to linearly increase with respect to the reduced velocity, and slopes for linear relations were found to be identical for the three cases tested. 展开更多
关键词 flow-induced vibration low mass ratio flexible cylinder multi-frequency response hydrodynamic response
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Hydrodynamic Response of A Fully Coupled TLP Hull-TTR System with Detailed Modeling of A Hydraulic Pneumatic Tensioner and Riser Joints
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作者 HAO Shuai YU Yang +2 位作者 YU Jian-xing YUAN Zhi-ming XU Li-xin 《China Ocean Engineering》 SCIE EI CSCD 2022年第3期451-463,共13页
Tension Leg Platform(TLP)in deepwater oil and gas field development usually consists of a hull,tendons,and top tension risers(TTRs).To maintain its top tension,each TTR is connected with a tensioner system to the hull... Tension Leg Platform(TLP)in deepwater oil and gas field development usually consists of a hull,tendons,and top tension risers(TTRs).To maintain its top tension,each TTR is connected with a tensioner system to the hull.Owing to the complicated configuration of the tensioners,the hull and TTRs form a strong coupled system.Traditionally,some simplified tensioner models are applied to analyze the TLP structures.There is a large discrepancy between their analysis results and the actual mechanism behaviors of a tensioner.It is very necessary to develop a more detailed tensioner model to consider the coupling effects between TLP and TTRs.In the present study,a fully coupled TLP hull-TTR system for hydrodynamic numerical simulation is established.A specific hydraulic pneumatic tensioner is modeled by considering 4 cylinders.The production TTR model is stacked up by specific riser joints.The simulation is also extended to analyze an array of TTRs.Different regular and irregular waves are considered.The behaviors of different cylinders are presented.The results show that it is important to consider the specific configurations of the tensioner and TTRs,which may lead to obviously different response behaviors,compared with those from a simplified model. 展开更多
关键词 top tension riser(TTR) fully coupled hull-tendon-TTR-tensioner model hydraulic pneumatic tensioner hydrodynamic response 3D potential flow theory
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Experimental Study on Hydrodynamic Response of Semisubmersible Platform-Based Bottom-Hinged Flap Wave Energy Converter 被引量:1
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作者 LIN Yan PEI Fei 《Journal of Shanghai Jiaotong university(Science)》 EI 2022年第3期307-315,共9页
A semisubmersible platform-based(SPB)bottom-hinged flap(BHF)wave energy converter(WEC)concept is presented in this paper,and its platform hydrodynamic response was studied experimentally.Aimed at studying the special ... A semisubmersible platform-based(SPB)bottom-hinged flap(BHF)wave energy converter(WEC)concept is presented in this paper,and its platform hydrodynamic response was studied experimentally.Aimed at studying the special WEC-mounted platform response problem,both regular and irregular wave experiments were conducted.The frequency domain results of regular wave experiments are described in the form of response amplitude operators.The time domain results of irregular wave experiments are treated by statistical analysis and fast Fourier transformation.Regular wave experiments and irregular wave experiments show good consistency.The mooring system strongly affects the whole system,which is a considerable factor for WEC design.The influences of BHF mounted on the platform are revealed in both statistic and frequency spectral ways.The results of experiments give a guide for SPB design aiming to support BHF-WEC. 展开更多
关键词 wave energy converter(WEC) hydrodynamic response wave tank experiment mooring design
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Hybrid Model Testing Technique for Deep-Sea Platforms Based on Equivalent Water Depth Truncation 被引量:4
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作者 张火明 杨建民 肖龙飞 《China Ocean Engineering》 SCIE EI 2007年第3期401-416,共16页
In this paper, an inner turret moored FPSO which works in the water of 320 m depth, is selected to study the socalled "passively-truncated + numerical-simulation" type of hybrid model testing technique while the tn... In this paper, an inner turret moored FPSO which works in the water of 320 m depth, is selected to study the socalled "passively-truncated + numerical-simulation" type of hybrid model testing technique while the tnmcated water depth is 160 m and the model scale ), = 80. During the investigation, the optimization design of the equivalent-depth truncated system is performed by using the similarity of the static characteristics between the truncated system and the full depth one as the objective function. According to the truncated system, the corresponding physical test model is made. By adopting the coupling time domain simulation method, the tnmcated system model test is numerically reconstructed to carefully verify the computer simulation software and to adjust the corresponding hydrodynamic parameters. Based on the above work, the numerical extrapolation to the full depth system is performed by using the verified computer software and the adjusted hydrodyrmmic parameters. The full depth system model test is then performed in the basin and the results are compared with those from the numerical extrapolation. At last, the implementation procedure and the key technique of the hybrid model testing of the deep-sea platforms are summarized and printed. Through the above investigations, some beneficial conclusions are presented. 展开更多
关键词 hybrid model testing technique equivalent water depth truncation FPSO hydrodynamic response TURRET
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Investigation on Effects of Mooring Line Fractures and Connector Failures for A Hybrid Modular Floating Structure System
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作者 LIU Ya-qiong REN Nian-xin OU Jin-ping 《China Ocean Engineering》 SCIE EI CSCD 2022年第6期880-893,共14页
The present work reports a Hybrid Modular Floating Structure(HMFS)system with typical malfunction conditions.The effects of both fractured mooring lines and failed connectors on main hydrodynamic responses(mooring lin... The present work reports a Hybrid Modular Floating Structure(HMFS)system with typical malfunction conditions.The effects of both fractured mooring lines and failed connectors on main hydrodynamic responses(mooring line tensions,module motions,connector loads and wave power production)of the HMFS system under typical sea con-ditions are comparatively investigated.The results indicate that the mooring tension distribution,certain module motions(surge,sway and yaw)and connector loads(Mz)are significantly influenced by mooring line fractures.The adjacent mooring line of the fractured line on the upstream side suffers the largest tension among the remaining mooring lines,and the case with two fractured mooring lines in the same group on the upstream side is the most dangerous among all cases of two-line failures in view of mooring line tensions,module motions and connector loads.There-fore,one emergency strategy with appropriate relaxation of a proper mooring line has been proposed and proved effective to reduce the risk of more progressive mooring line fractures.In addition,connector failures substantially affect certain module motions(heave and pitch),certain connector loads(Fz and My)and wave power production.The present work can be helpful and instructive for studies on malfunction conditions of modular floating structure(MFS)systems. 展开更多
关键词 Hybrid Modular Floating Structure(HMFS)system mooring line fractures connector failures hydrodynamic responses emergency strategy
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Numerical Study of Wave Energy Converter Platform Geometry Layout Design
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作者 PEI Fei LIN Yan 《Journal of Shanghai Jiaotong university(Science)》 EI 2024年第5期780-790,共11页
The present work is aimed at determining the optimal geometry layout of a wave energy converter platform for plate energy harvesting performance.A linear potential fluid theory method was applied to analyzing the inte... The present work is aimed at determining the optimal geometry layout of a wave energy converter platform for plate energy harvesting performance.A linear potential fluid theory method was applied to analyzing the interaction between the platform and plate.Three factors of layout geometry were tested and the performance of the plate was analyzed.The methodology of design of experiments was used to confirm factor significance and build response surface model.The 1st order model and the 2nd order model were built to describe the relation between factors and plate performance.The significance of two factors and their interactions were revealed,and an optimal parameter set was found.The wave form in front of the plate confirmed the interactions.It is clear that a wide entrance and enclosing channel for waves can maximize the plate performance. 展开更多
关键词 wave energy converter hydrodynamic response design of experiments response surface methodology factorial design
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Detailed parametric design methodology for hydrodynamics of liquid-solid circulating fluidized bed using design of experiments 被引量:1
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作者 Ritesh Ramesh Palkar Vidyasagar Shilapuram 《Particuology》 SCIE EI CAS CSCD 2017年第2期59-68,共10页
A design-of-experiments methodology is used to develop a statistical model for the prediction of the hydrodynamics of a liquid–solid circulating fluidized bed. To illustrate the multilevel factorial design approach, ... A design-of-experiments methodology is used to develop a statistical model for the prediction of the hydrodynamics of a liquid–solid circulating fluidized bed. To illustrate the multilevel factorial design approach, a step by step methodology is taken to study the effects of the interactions among the independent factors considered on the performance variables. A multilevel full factorial design with three levels of the two factors and five levels of the third factor has been studied. Various statistical models such as the linear, two-factor interaction, quadratic, and cubic models are tested. The model has been developed to predict responses, viz., average solids holdup and solids circulation rate. The validity of the developed regression model is verified using the analysis of variance. Furthermore, the model developed was compared with an experimental dataset to assess its adequacy and reliability. This detailed statistical design methodology for non-linear systems considered here provides a very important tool for design and optimization in a cost-effective approach 展开更多
关键词 hydrodynamics Liquid-solid circulating fluidized bed Statistical design Factorial design approach response prediction Analysis of variance
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