Dr. Haixiao Liu, Depeng Jiao, Zhou Li, Chenyang Zhang, Yancheng Yang
Abstract Being the latest representative of GIAs, the OMNI-Max anchor performs comprehensive behaviors in the seabed, like keying and diving, by adjusting orientation and position to derive higher capacity and therefore to avoid anchor failure. Current research of OMNI-Max anchors is concentrated on clay, while there is a notable gap of the work on sand. During the keying process of GIAs, many factors may influence the keying capacity, such as the embedment depth, the anchor orientation, the rotational center, the bearing area and the soil strength. Large deformation finite element analyses combined with a bounding-surface plasticity constitutive model are performed to investigate systematically the keying behavior of GIAs. A series of analytical cases involving multiple factors are designed and analyzed to explore the effects of various factors on the keying capacity of GIAs, defined by the soil resistance coefficient during keying. The soil resistance coefficient increases with increasing soil density, while it tends to be stable with the increase of the embedment depth. The closer the rotational center approaches to the two ends of the anchor, the greater the soil resistance coefficient becomes. An explicit expression of the soil resistance coefficient during keying is derived to quantify the effects of various factors. These findings are helpful to understand further the comprehensive anchor behaviors and to promote the application of GIAs in offshore engineering.
{"title":"Numerical study on keying capacity of gravity installed anchors in sand","authors":"Dr. Haixiao Liu, Depeng Jiao, Zhou Li, Chenyang Zhang, Yancheng Yang","doi":"10.1115/1.4063937","DOIUrl":"https://doi.org/10.1115/1.4063937","url":null,"abstract":"Abstract Being the latest representative of GIAs, the OMNI-Max anchor performs comprehensive behaviors in the seabed, like keying and diving, by adjusting orientation and position to derive higher capacity and therefore to avoid anchor failure. Current research of OMNI-Max anchors is concentrated on clay, while there is a notable gap of the work on sand. During the keying process of GIAs, many factors may influence the keying capacity, such as the embedment depth, the anchor orientation, the rotational center, the bearing area and the soil strength. Large deformation finite element analyses combined with a bounding-surface plasticity constitutive model are performed to investigate systematically the keying behavior of GIAs. A series of analytical cases involving multiple factors are designed and analyzed to explore the effects of various factors on the keying capacity of GIAs, defined by the soil resistance coefficient during keying. The soil resistance coefficient increases with increasing soil density, while it tends to be stable with the increase of the embedment depth. The closer the rotational center approaches to the two ends of the anchor, the greater the soil resistance coefficient becomes. An explicit expression of the soil resistance coefficient during keying is derived to quantify the effects of various factors. These findings are helpful to understand further the comprehensive anchor behaviors and to promote the application of GIAs in offshore engineering.","PeriodicalId":50106,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136261857","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jonathan Procel, Marco Guamán, Wilson Guachamín Acero
Abstract Execution of a marine operation (MO) requires coordinated actions of several vessels conducting simultaneous and sequential offshore activities. These activities have their operational limits given in terms of environmental parameters. Wave parameters are important because of their high energetic level. During the execution of a MO, forecast wave spectral parameters, i.e. significant wave height (Hs), peak period (Tp), and peak direction, are used to make an on-board decision. For critical operations, the use of forecasts can be complemented with buoy measurements. This paper proposes to use synthetic statistics of vessel dynamic responses to predict “real-time” wave spectral parameters using multi-output machine learning (ML) regression algorithms. For a case study of a vessel with no forward speed, it is observed that the random forest model predicts accurate Hs and Tp parameters. The prediction of wave direction is not very accurate but it can be corrected with on-board observations. The random forest model has good performance; it is efficient, useful for practical purposes, and comparable with other deep learning models reported in scientific literature. Findings from this research can be valuable for real-time assessment of wave spectral parameters, which are necessary to support decision-making during the execution of MOs.
{"title":"Prediction of wave spectral parameters using multiple-output regression models to support the execution of marine operations","authors":"Jonathan Procel, Marco Guamán, Wilson Guachamín Acero","doi":"10.1115/1.4063938","DOIUrl":"https://doi.org/10.1115/1.4063938","url":null,"abstract":"Abstract Execution of a marine operation (MO) requires coordinated actions of several vessels conducting simultaneous and sequential offshore activities. These activities have their operational limits given in terms of environmental parameters. Wave parameters are important because of their high energetic level. During the execution of a MO, forecast wave spectral parameters, i.e. significant wave height (Hs), peak period (Tp), and peak direction, are used to make an on-board decision. For critical operations, the use of forecasts can be complemented with buoy measurements. This paper proposes to use synthetic statistics of vessel dynamic responses to predict “real-time” wave spectral parameters using multi-output machine learning (ML) regression algorithms. For a case study of a vessel with no forward speed, it is observed that the random forest model predicts accurate Hs and Tp parameters. The prediction of wave direction is not very accurate but it can be corrected with on-board observations. The random forest model has good performance; it is efficient, useful for practical purposes, and comparable with other deep learning models reported in scientific literature. Findings from this research can be valuable for real-time assessment of wave spectral parameters, which are necessary to support decision-making during the execution of MOs.","PeriodicalId":50106,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136262003","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jiaqi Zhou, Junsheng Ren, Dongyue Li, Can Tu, Weiwei Bai
Abstract Vortex has attracted attention because it is the main factor affecting the flow characteristics around offshore structures. This paper researches the flow field variations around a semi-submerged rectangular cylinder (SRC) under four aspect ratios, thereby revealing the bottom vortex effects on the flow field at Reynolds number = 36300. According to the particle image velocimetry (PIV) data, the RNG k-ε model is selected as an applicable turbulence model for studying SRC flow characteristics. From the results, the bottom vortex generation and streamwise velocity are inseparable. As the draft increases, the increased range of the bottom vortex would directly interfere with the flow characteristic around the SRC. Since the wake vortex forms a reattachment state when the SRC pierces the free surface, its flow field could be disturbed by the bottom vortex. Furthermore, the bottom vortex also affects the extreme point position of the boundary layer characteristic at the SRC bottom.
{"title":"Impacts of the bottom vortex on the surrounding flow characteristics of a semi-submerged rectangular cylinder under four aspect ratios","authors":"Jiaqi Zhou, Junsheng Ren, Dongyue Li, Can Tu, Weiwei Bai","doi":"10.1115/1.4063853","DOIUrl":"https://doi.org/10.1115/1.4063853","url":null,"abstract":"Abstract Vortex has attracted attention because it is the main factor affecting the flow characteristics around offshore structures. This paper researches the flow field variations around a semi-submerged rectangular cylinder (SRC) under four aspect ratios, thereby revealing the bottom vortex effects on the flow field at Reynolds number = 36300. According to the particle image velocimetry (PIV) data, the RNG k-ε model is selected as an applicable turbulence model for studying SRC flow characteristics. From the results, the bottom vortex generation and streamwise velocity are inseparable. As the draft increases, the increased range of the bottom vortex would directly interfere with the flow characteristic around the SRC. Since the wake vortex forms a reattachment state when the SRC pierces the free surface, its flow field could be disturbed by the bottom vortex. Furthermore, the bottom vortex also affects the extreme point position of the boundary layer characteristic at the SRC bottom.","PeriodicalId":50106,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135570285","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract This research addresses the mathematical solution of the elastic catenary, a fundamental problem in offshore mooring engineering. A novel exact solution in a non-Lagrangian form is developed through rigorous mathematical derivation, distinguishing it from classical Lagrangian solutions. The procedure is described in detail, and the resulting expressions are applied to analyze the mooring system of a reference floating turbine. A general analytical approach is introduced to solve the transcendental equations associated with catenary mooring problems. The newly derived formulae exhibit greater applicability to geometry-to-force problems compared to existing Lagrangian expressions, making them particularly valuable for conceptual design and front-end engineering. In summary, this work provides valuable new insights into the exact solution of the elastic catenary, enhancing understanding and enabling practical applications in the field of floating wind turbines.
{"title":"Novel exact solution of elastic catenary and applications on floating wind turbine mooring systems","authors":"Pengpeng Xu, Xing Chang, Yuan E. Liu","doi":"10.1115/1.4063852","DOIUrl":"https://doi.org/10.1115/1.4063852","url":null,"abstract":"Abstract This research addresses the mathematical solution of the elastic catenary, a fundamental problem in offshore mooring engineering. A novel exact solution in a non-Lagrangian form is developed through rigorous mathematical derivation, distinguishing it from classical Lagrangian solutions. The procedure is described in detail, and the resulting expressions are applied to analyze the mooring system of a reference floating turbine. A general analytical approach is introduced to solve the transcendental equations associated with catenary mooring problems. The newly derived formulae exhibit greater applicability to geometry-to-force problems compared to existing Lagrangian expressions, making them particularly valuable for conceptual design and front-end engineering. In summary, this work provides valuable new insights into the exact solution of the elastic catenary, enhancing understanding and enabling practical applications in the field of floating wind turbines.","PeriodicalId":50106,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135570272","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Qun Cao, Zhengshun Cheng, Longfei Xiao, Mingyue Liu
Abstract Three forms of mooring system in 60 m water depth are proposed for SPIC (Semi-submersible with Partially Inclined Columns) concept FWT (Floating Wind Turbine). One is a simple form with only catenary lines, and the others are hybrid forms including clump weights. The clumps are attached to the suspended section for Hybrid form1 and the bottom section for Hybrid form2. Hybrid form2 achieves the smallest line length and chain weight. Three proposals can be evaluated through mooring line characteristics, dynamic responses, utilization factors and cost analysis. Hybrid form2 allows for smallest pretension, and largest stiffness and nonlinearity only at large offsets. Under operational conditions, the mean surge for Hybrid form1 and Hybrid form2 is similar, but the fairlead tension is significantly smaller for Hybrid form2. Under survival condition, the clumps of Hybrid form2 are lifted up and put down, leading to large wave-frequency components of line tension. Among the three forms, the hybrid form2 can limit the FWT to the smallest offset range while also controlling the mean line tension to a level similar to the other two forms. Under normal working conditions and accidental conditions with single line broken, the maximal surge motions of FWT under the restraint of three forms all meet the design requirements. The mooring line strength of the three forms meets the requirements in ULS (ultimate limit state) and ALS (accidental limit state) analysis. Among them, the utilization coefficient of Hybrid form2 is closest to 1, demonstrating its best economic performance.
{"title":"Dynamic Analysis of Three Alternative Mooring Systems for a Semi-submersible Wind Turbine in Intermediate Water Depth","authors":"Qun Cao, Zhengshun Cheng, Longfei Xiao, Mingyue Liu","doi":"10.1115/1.4063854","DOIUrl":"https://doi.org/10.1115/1.4063854","url":null,"abstract":"Abstract Three forms of mooring system in 60 m water depth are proposed for SPIC (Semi-submersible with Partially Inclined Columns) concept FWT (Floating Wind Turbine). One is a simple form with only catenary lines, and the others are hybrid forms including clump weights. The clumps are attached to the suspended section for Hybrid form1 and the bottom section for Hybrid form2. Hybrid form2 achieves the smallest line length and chain weight. Three proposals can be evaluated through mooring line characteristics, dynamic responses, utilization factors and cost analysis. Hybrid form2 allows for smallest pretension, and largest stiffness and nonlinearity only at large offsets. Under operational conditions, the mean surge for Hybrid form1 and Hybrid form2 is similar, but the fairlead tension is significantly smaller for Hybrid form2. Under survival condition, the clumps of Hybrid form2 are lifted up and put down, leading to large wave-frequency components of line tension. Among the three forms, the hybrid form2 can limit the FWT to the smallest offset range while also controlling the mean line tension to a level similar to the other two forms. Under normal working conditions and accidental conditions with single line broken, the maximal surge motions of FWT under the restraint of three forms all meet the design requirements. The mooring line strength of the three forms meets the requirements in ULS (ultimate limit state) and ALS (accidental limit state) analysis. Among them, the utilization coefficient of Hybrid form2 is closest to 1, demonstrating its best economic performance.","PeriodicalId":50106,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135570133","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract In this work, we analyze the effect of multiple thick porous layers, fitted around a rigid vertical circular cylinder, on the wave forces acting on the rigid structure. Using the eigenfunction expansion method in cylindrical coordinates, we derive the expressions for velocity potentials in the respective domains and finally calculate the wave force acting on the rigid structure by integrating the pressure term. Consideration of the multiple porous layers, each with different porosities, gives rise to a very basic question to answer: what will be the appropriate arrangement of the porous layers to reduce the wave impact? Hence, for numerical study, we consider three different arrangements of the porous layers. For such arrangements of the porous layers, we also analyze the effects of the other crucial parameters, such as the number and the thickness of the porous layers, on the wave force. The key finding of the analysis is that the wave force acting on the rigid structure can be minimized by increasing the number of porous layers with decreasing porosity from the innermost layer to the outermost layer. The wave breaking and forced oscillations for certain values of the porous impedance parameter are some of the interesting observations. The present model is also verified against an existing work in the literature which shows an excellent agreement.
{"title":"Analysis of wave force and run-up acting on an impermeable vertical circular cylinder surrounded by multiple thick porous layers","authors":"Sunanda Saha, Swaroop Nandan Bora","doi":"10.1115/1.4063497","DOIUrl":"https://doi.org/10.1115/1.4063497","url":null,"abstract":"Abstract In this work, we analyze the effect of multiple thick porous layers, fitted around a rigid vertical circular cylinder, on the wave forces acting on the rigid structure. Using the eigenfunction expansion method in cylindrical coordinates, we derive the expressions for velocity potentials in the respective domains and finally calculate the wave force acting on the rigid structure by integrating the pressure term. Consideration of the multiple porous layers, each with different porosities, gives rise to a very basic question to answer: what will be the appropriate arrangement of the porous layers to reduce the wave impact? Hence, for numerical study, we consider three different arrangements of the porous layers. For such arrangements of the porous layers, we also analyze the effects of the other crucial parameters, such as the number and the thickness of the porous layers, on the wave force. The key finding of the analysis is that the wave force acting on the rigid structure can be minimized by increasing the number of porous layers with decreasing porosity from the innermost layer to the outermost layer. The wave breaking and forced oscillations for certain values of the porous impedance parameter are some of the interesting observations. The present model is also verified against an existing work in the literature which shows an excellent agreement.","PeriodicalId":50106,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135667261","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Vinícius Batista Godoy, Fernando Schnaid, Eduardo Cirio, Hugo Scheuermann Filho, Adriana Leonhardt, Inácio Abreu Pestana
The study of the geomechanical behavior of marine clays is a basic requirement for project optimization of the oil and natural gas industry. As part of a large-scale project, this study explored the effects of moisture content, temperature and rate effects using laboratory vane shear tests. A series of results has helped in the identification of the effects of ground freezing on the undrained shear strength. For temperatures below freezing (−2.0°C) the undrained shear strength increases with increasing water content and decreases with increasing shear rates for applied angular velocities in the range of 0.0025 to 0.015 rpm. Apparently, with the freezing of pore fluids, the shear strength is partially governed by the strength of the ice-soil particle bonds. The increase in shear rate appears to facilitate the breakage of the ice-bonds and afterwards the ice crystals reducing the viscous effects on the mobilized shear strength. Conversely, samples tested at temperatures above freezing, show an increase in undrained shear strength with the increase in the imposed angular velocity, and decreases with increasing soil moisture. Based on these studies, it is concluded that rate effects should be coupled to the influence of temperature and moisture content in design of offshore structures.
{"title":"Influence of rate effects, temperature and moisture content on the geomechanical behavior of marine clays","authors":"Vinícius Batista Godoy, Fernando Schnaid, Eduardo Cirio, Hugo Scheuermann Filho, Adriana Leonhardt, Inácio Abreu Pestana","doi":"10.1115/1.4063699","DOIUrl":"https://doi.org/10.1115/1.4063699","url":null,"abstract":"The study of the geomechanical behavior of marine clays is a basic requirement for project optimization of the oil and natural gas industry. As part of a large-scale project, this study explored the effects of moisture content, temperature and rate effects using laboratory vane shear tests. A series of results has helped in the identification of the effects of ground freezing on the undrained shear strength. For temperatures below freezing (−2.0°C) the undrained shear strength increases with increasing water content and decreases with increasing shear rates for applied angular velocities in the range of 0.0025 to 0.015 rpm. Apparently, with the freezing of pore fluids, the shear strength is partially governed by the strength of the ice-soil particle bonds. The increase in shear rate appears to facilitate the breakage of the ice-bonds and afterwards the ice crystals reducing the viscous effects on the mobilized shear strength. Conversely, samples tested at temperatures above freezing, show an increase in undrained shear strength with the increase in the imposed angular velocity, and decreases with increasing soil moisture. Based on these studies, it is concluded that rate effects should be coupled to the influence of temperature and moisture content in design of offshore structures.","PeriodicalId":50106,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135667706","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jonathan Soper, Erik Veitch, Rebecca Thistle, Jennifer Smith, Brian Veitch
Abstract Ice management is essential for maintaining the safety of offshore operations in Arctic regions. We present the combined results of three experiments conducted in a full-mission bridge simulator specially designed for ice management. From a quantitative analysis of the results, we infer the effect of three variables on performance: (1) experience, (2) training, and (3) Decision Support System (DSS). The results confirm that experience and training improve performance for untrained and inexperienced simulator participants. The DSS also improves performance, but with a smaller effect. Qualitative observations using vessel position heat-map diagrams and exit interviews suggested that novice participants using the DSS adopted expert strategies but carried out their tasks more slowly and with less precision. This has important consequences for the design of a future DSS used in training simulators or onboard ships. Potential improvements to the DSS design might include real-time feedback to the user, a redesign of the human–machine interface (HMI), and increasing user input and customization with a human factors focus.
{"title":"An Analysis of Factors Influencing Ice Management Performance in an Experimental Marine Simulator and their Application to Decision Support System Design","authors":"Jonathan Soper, Erik Veitch, Rebecca Thistle, Jennifer Smith, Brian Veitch","doi":"10.1115/1.4063617","DOIUrl":"https://doi.org/10.1115/1.4063617","url":null,"abstract":"Abstract Ice management is essential for maintaining the safety of offshore operations in Arctic regions. We present the combined results of three experiments conducted in a full-mission bridge simulator specially designed for ice management. From a quantitative analysis of the results, we infer the effect of three variables on performance: (1) experience, (2) training, and (3) Decision Support System (DSS). The results confirm that experience and training improve performance for untrained and inexperienced simulator participants. The DSS also improves performance, but with a smaller effect. Qualitative observations using vessel position heat-map diagrams and exit interviews suggested that novice participants using the DSS adopted expert strategies but carried out their tasks more slowly and with less precision. This has important consequences for the design of a future DSS used in training simulators or onboard ships. Potential improvements to the DSS design might include real-time feedback to the user, a redesign of the human–machine interface (HMI), and increasing user input and customization with a human factors focus.","PeriodicalId":50106,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135666684","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Clean energy captured by offshore wind turbines have been widely used for supporting onshore activities. In the near future, facilities such as offshore wind turbines can also play an important role in energy transition of offshore activities. Offshore wind energy can be employed for electrifying the operations in offshore fish farms, which are traditionally supplied by diesel-engine barges/generators. Based on this motivation, this study focuses on a design of shared mooring system between a semi-submersible offshore fish cage and a spar-type floating wind turbine. A numerical model of the proposed shared-mooring system is implemented in a global response analysis software SIMA for performing fully coupled time domain simulations. The configuration of the shared mooring line is determined using an engineering approach which comprises Irvine's formulation, system eigenvalue analysis and cost estimation. Moreover, relevant case studies by altering the environmental conditions are performed. Extreme operational conditions that may give large relative motions are investigated thoroughly. The dynamic performance of the integrated system is compared with that of individual structures. The global motion of the floating wind turbine and its mooring line's tension behavior are obviously influenced by the existence of the shared line. In general, the present work investigates the feasibility of a shared-mooring system for these types of offshore structures and further gives insights about the engineering design procedure.
{"title":"Design and dynamic analysis of a co-existence solution between a semi-submersible offshore fish cage and a spar-type floating offshore wind turbine","authors":"Yu Ma, Lin Li, Muk Chen Ong, Jingzhe Jin, Biao Su","doi":"10.1115/1.4063806","DOIUrl":"https://doi.org/10.1115/1.4063806","url":null,"abstract":"Abstract Clean energy captured by offshore wind turbines have been widely used for supporting onshore activities. In the near future, facilities such as offshore wind turbines can also play an important role in energy transition of offshore activities. Offshore wind energy can be employed for electrifying the operations in offshore fish farms, which are traditionally supplied by diesel-engine barges/generators. Based on this motivation, this study focuses on a design of shared mooring system between a semi-submersible offshore fish cage and a spar-type floating wind turbine. A numerical model of the proposed shared-mooring system is implemented in a global response analysis software SIMA for performing fully coupled time domain simulations. The configuration of the shared mooring line is determined using an engineering approach which comprises Irvine's formulation, system eigenvalue analysis and cost estimation. Moreover, relevant case studies by altering the environmental conditions are performed. Extreme operational conditions that may give large relative motions are investigated thoroughly. The dynamic performance of the integrated system is compared with that of individual structures. The global motion of the floating wind turbine and its mooring line's tension behavior are obviously influenced by the existence of the shared line. In general, the present work investigates the feasibility of a shared-mooring system for these types of offshore structures and further gives insights about the engineering design procedure.","PeriodicalId":50106,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135993953","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract The design of a floating wind turbine (FWT) should satisfy the serviceability limit state (SLS) requirement for an efficient and safe operation throughout the entire work life. The SLS requirements are introduced by the owner/developer of the wind turbine facility to achieve production of power or an efficient operation of the facility or a first step towards ensuring safety. Currently, there are limited information about SLS requirements in design standards. This study deals with an assessment of current methods, criteria and procedure for the SLS design check with an emphasis on tilt/pitch and nacelle accelerations in view of power production and its fluctuations. Moreover, other criteria, on the borderline between serviceability and safety criteria, e.g. relating to clearance, are briefly discussed. The criteria relating to power production are illustrated in a case study with a 10-MW semi-submersible FWT considered for an offshore site in the Northern North Sea. Static and dynamic analysis in terms of serviceability are presented, discussed and applied in the case study. A good understanding of wind turbine dynamic performance associated with serviceability is essential to facilitate design decision-making. The relative contribution of wind and wave loads to the different SLS criteria is investigated. Finally, the main conclusions are summarized. I lieu of the current state of the art regarding SLS requirements for FWTs, we hope that this study provides a basis for improving design standards and guiding research and engineering practice for the semi-submersible floater design of FWTs.
{"title":"SERVICEABILITY LIMIT STATE ASSESSMENT OF SEMI-SUBMERSIBLE FLOATING WIND TURBINES","authors":"Shuaishuai Wang, Torgeir Moan","doi":"10.1115/1.4063618","DOIUrl":"https://doi.org/10.1115/1.4063618","url":null,"abstract":"Abstract The design of a floating wind turbine (FWT) should satisfy the serviceability limit state (SLS) requirement for an efficient and safe operation throughout the entire work life. The SLS requirements are introduced by the owner/developer of the wind turbine facility to achieve production of power or an efficient operation of the facility or a first step towards ensuring safety. Currently, there are limited information about SLS requirements in design standards. This study deals with an assessment of current methods, criteria and procedure for the SLS design check with an emphasis on tilt/pitch and nacelle accelerations in view of power production and its fluctuations. Moreover, other criteria, on the borderline between serviceability and safety criteria, e.g. relating to clearance, are briefly discussed. The criteria relating to power production are illustrated in a case study with a 10-MW semi-submersible FWT considered for an offshore site in the Northern North Sea. Static and dynamic analysis in terms of serviceability are presented, discussed and applied in the case study. A good understanding of wind turbine dynamic performance associated with serviceability is essential to facilitate design decision-making. The relative contribution of wind and wave loads to the different SLS criteria is investigated. Finally, the main conclusions are summarized. I lieu of the current state of the art regarding SLS requirements for FWTs, we hope that this study provides a basis for improving design standards and guiding research and engineering practice for the semi-submersible floater design of FWTs.","PeriodicalId":50106,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135697774","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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