Green water and slamming wave impacts can lead to severe damage or operability issues for marine structures. It is therefore essential to consider their probability and loads in design. This is difficult, as impacts are both hydrodynamically complex and relatively rare. The complexity requires high-fidelity modelling (experiments or CFD), whereas a statistically sound analysis of rare events requires long durations. High-fidelity tools are too demanding to run a Monte-Carlo simulation; low fidelity tools do not include sufficient physical details. The use of extreme value theory and / or multi-fidelity modeling is therefore required. The present paper reviews the state-of-the-art methods to find wave impact design loads, which include response-conditioning methods, screening methods and adaptive sampling methods. Their benefits and shortcomings are discussed, as well as challenges for the wave impact problem. One challenge is the role of wave non-linearity. Another is the validation of the different methods; it is hard to obtain long-duration high fidelity wave impact data.
{"title":"Finding dangerous waves – Review of methods to obtain wave impact design loads for marine structures","authors":"S. V. van Essen, H. Seyffert","doi":"10.1115/1.4056888","DOIUrl":"https://doi.org/10.1115/1.4056888","url":null,"abstract":"\u0000 Green water and slamming wave impacts can lead to severe damage or operability issues for marine structures. It is therefore essential to consider their probability and loads in design. This is difficult, as impacts are both hydrodynamically complex and relatively rare. The complexity requires high-fidelity modelling (experiments or CFD), whereas a statistically sound analysis of rare events requires long durations. High-fidelity tools are too demanding to run a Monte-Carlo simulation; low fidelity tools do not include sufficient physical details. The use of extreme value theory and / or multi-fidelity modeling is therefore required. The present paper reviews the state-of-the-art methods to find wave impact design loads, which include response-conditioning methods, screening methods and adaptive sampling methods. Their benefits and shortcomings are discussed, as well as challenges for the wave impact problem. One challenge is the role of wave non-linearity. Another is the validation of the different methods; it is hard to obtain long-duration high fidelity wave impact data.","PeriodicalId":50106,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2023-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48739142","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}
In this paper, a method that estimates the real-time behavior of subsea line structures based on sequential data assimilation with distributed strain sensors is proposed. A finite element method is used to represent the behavior of subsea line structures and generates ensemble forecasts regarding unknown parameters. A merging particle filter technique is applied to integrate the observation data with the numerical models to calculate the posterior probability density function. The effectiveness of the proposed method is examined through twin experiments. The presented results validate the proposed method's capability to estimate the current state as well as unknown parameters of subsea line structures. The results suggest the advantage of distributed sensors against pointwise sensing when applied to line structures.
{"title":"Estimation of Subsea Line Structure Behavior Based on Sequential Data Assimilation with Distributed Sensing","authors":"S. Kojima, Ryota Wada, H. Murayama","doi":"10.1115/1.4056846","DOIUrl":"https://doi.org/10.1115/1.4056846","url":null,"abstract":"\u0000 In this paper, a method that estimates the real-time behavior of subsea line structures based on sequential data assimilation with distributed strain sensors is proposed. A finite element method is used to represent the behavior of subsea line structures and generates ensemble forecasts regarding unknown parameters. A merging particle filter technique is applied to integrate the observation data with the numerical models to calculate the posterior probability density function. The effectiveness of the proposed method is examined through twin experiments. The presented results validate the proposed method's capability to estimate the current state as well as unknown parameters of subsea line structures. The results suggest the advantage of distributed sensors against pointwise sensing when applied to line structures.","PeriodicalId":50106,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2023-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47947602","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}
M. Eriksson, Magnus Nyberg, Michael Andersen, Jørgen Nielsen, Jesper Tychsen
Non-linear finite element analysis is a powerful tool for determination of ultimate capacities of steel components. To produce reliable predictions of structural strength, it is of fundamental importance that non-linear finite element analyses are based on a validated methodology. This paper focuses on physical test campaigns, which are designed with the purpose of providing an experimental foundation for calibrated and validated non-linear finite element assessments of plated components, which form part of typical offshores structures. The experimental work discussed in the current paper is a continuation of the experiments of tubular members and joints, which were carried out by Maersk Oil in the late nineties. The objective is that the two-test campaigns together shall allow for development of a non-linear finite element methodology with calibrated failure criteria providing either characteristic or mean level of capacity/response for the main details in typical offshore structures. This paper particularly focuses on the testing campaign complete in 2017 which forms the basis for the calibration of the failure criteria covering plated sections.
{"title":"PHYSICAL TESTING CAMPAIGN FACILITATING VALIDATION OF WELDED STEEL STRUCTURES BY NON-LINEAR FINITE ELEMENT ANALYSIS","authors":"M. Eriksson, Magnus Nyberg, Michael Andersen, Jørgen Nielsen, Jesper Tychsen","doi":"10.1115/1.4056785","DOIUrl":"https://doi.org/10.1115/1.4056785","url":null,"abstract":"\u0000 Non-linear finite element analysis is a powerful tool for determination of ultimate capacities of steel components. To produce reliable predictions of structural strength, it is of fundamental importance that non-linear finite element analyses are based on a validated methodology. This paper focuses on physical test campaigns, which are designed with the purpose of providing an experimental foundation for calibrated and validated non-linear finite element assessments of plated components, which form part of typical offshores structures. The experimental work discussed in the current paper is a continuation of the experiments of tubular members and joints, which were carried out by Maersk Oil in the late nineties. The objective is that the two-test campaigns together shall allow for development of a non-linear finite element methodology with calibrated failure criteria providing either characteristic or mean level of capacity/response for the main details in typical offshore structures. This paper particularly focuses on the testing campaign complete in 2017 which forms the basis for the calibration of the failure criteria covering plated sections.","PeriodicalId":50106,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2023-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46451566","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}
The purpose of the present study is to reduce the high wave load on a sea wall by utilizing an elastic plate (EP) kept at fixed distance from a porous structure (PS). Thin plate theory is used to model the flow past EP, while Sollit and Cross theory is used to model the flow past PS. A linear potential theory-based analytical solution to the current problem is developed using the eigenfunction expansion technique. To understand the effect of PS and EP in creating tranquility zone and minimum wave loads on the rigid wall, horizontal wave force on the wall, reflection coefficient, dissipation coefficient and free surface elevation are computed and analyzed for different values of width and friction factor of PS, flexural rigidity and length of EP, angle of incidence, and distance between PS and EP, and the distance between EP and rigid wall. The study demonstrates that both structures considerably reduce the stress on the rigid wall and the wave reflection. It is found that the force on the wall shifted to the left as the width and frictional factor of PS increased. It is observed that PS effectively minimises the free surface elevation in the region between EP and the wall. It is also found that an effective tranquility zone may be produced, which will put less wave force on the rigid wall, with sufficient spacing between PS and EP, and EP and wall. The given model is expected to assist in preserving various coastal assets significantly.
{"title":"Mitigation of Wave Impact on Sea Wall by a Floating Elastic Plate and a Porous Structure","authors":"G. Sahoo, S. Singla, S. C. Martha","doi":"10.1115/1.4056787","DOIUrl":"https://doi.org/10.1115/1.4056787","url":null,"abstract":"\u0000 The purpose of the present study is to reduce the high wave load on a sea wall by utilizing an elastic plate (EP) kept at fixed distance from a porous structure (PS). Thin plate theory is used to model the flow past EP, while Sollit and Cross theory is used to model the flow past PS. A linear potential theory-based analytical solution to the current problem is developed using the eigenfunction expansion technique. To understand the effect of PS and EP in creating tranquility zone and minimum wave loads on the rigid wall, horizontal wave force on the wall, reflection coefficient, dissipation coefficient and free surface elevation are computed and analyzed for different values of width and friction factor of PS, flexural rigidity and length of EP, angle of incidence, and distance between PS and EP, and the distance between EP and rigid wall. The study demonstrates that both structures considerably reduce the stress on the rigid wall and the wave reflection. It is found that the force on the wall shifted to the left as the width and frictional factor of PS increased. It is observed that PS effectively minimises the free surface elevation in the region between EP and the wall. It is also found that an effective tranquility zone may be produced, which will put less wave force on the rigid wall, with sufficient spacing between PS and EP, and EP and wall. The given model is expected to assist in preserving various coastal assets significantly.","PeriodicalId":50106,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2023-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48101534","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 For structural design engineers, there is an apparent gap in how the hydrostatic pressure is treated between the American and European systems. In API RP-2A, the beam-column equations treat the axial and bending capacities the same as there is no hydrostatic pressure. This is physically not correct, as member utilization is a combination of hydrostatic, axial, and bending actions. In contrast, the ISO and NORSOK beam-column equations include reductions of axial and moment capacities due to hydrostatic effect. In this paper, available actual test data are compared with the API and ISO capacity equations. A third set of capacity equations provided by Chen et al. is also considered. Unity check (UC) results show that, although API equations lack the proper hydrostatic reduction in axial/bending capacities, it is compensated by the separate checks of hoop buckling and ultimate strength. For engineering applications, similar member designs will be obtained by either the European or the American systems.
{"title":"American and European Hydrostatic Tubular Beam-Column Equation Comparisons","authors":"Albert Ku, Mark Richmond","doi":"10.1115/1.4056620","DOIUrl":"https://doi.org/10.1115/1.4056620","url":null,"abstract":"Abstract For structural design engineers, there is an apparent gap in how the hydrostatic pressure is treated between the American and European systems. In API RP-2A, the beam-column equations treat the axial and bending capacities the same as there is no hydrostatic pressure. This is physically not correct, as member utilization is a combination of hydrostatic, axial, and bending actions. In contrast, the ISO and NORSOK beam-column equations include reductions of axial and moment capacities due to hydrostatic effect. In this paper, available actual test data are compared with the API and ISO capacity equations. A third set of capacity equations provided by Chen et al. is also considered. Unity check (UC) results show that, although API equations lack the proper hydrostatic reduction in axial/bending capacities, it is compensated by the separate checks of hoop buckling and ultimate strength. For engineering applications, similar member designs will be obtained by either the European or the American systems.","PeriodicalId":50106,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135793623","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}
Excessive acceleration is one of the stability failure modes involving large roll motion of ships. The overset method is applied to solve the six degrees-of-freedom motion of the ship with moonpool in beam waves. Based on computational fluid dynamics (CFD) method, the improved method of considering the roll damping of square moonpool are proposed. The improved method of considering moonpool damping is used in vulnerability assessment for excessive acceleration. The comparative analysis of the Level 1 and Level 2 vulnerability assessment of the excessive acceleration of a ship with moonpool is completed. The influence of moonpool on the vulnerability assessment of excessive acceleration is studied by comparing with the model test results. The results show that the main factor affecting the estimation accuracy of lateral acceleration of the ship is the accuracy of roll amplitude calculation. The existence of moonpool will reduce the roll damping coefficient of the ship. The improved methods proposed in this paper can effectively improve the estimation of lateral acceleration of ships with moonpool in the Level 1 vulnerability criteria and increase the safety margin in the Level 2 vulnerability assessment. In the direct stability assessment, the CFD method can simulate the large-amplitude roll motion of the ship with moonpool and bilge keels, and can capture the strong nonlinear phenomena
{"title":"An improved method for predicting roll damping and excessive acceleration for a ship with moonpool based on CFD method","authors":"F. Duan, N. Ma, X. Gu, Yao-hua Zhou","doi":"10.1115/1.4056737","DOIUrl":"https://doi.org/10.1115/1.4056737","url":null,"abstract":"\u0000 Excessive acceleration is one of the stability failure modes involving large roll motion of ships. The overset method is applied to solve the six degrees-of-freedom motion of the ship with moonpool in beam waves. Based on computational fluid dynamics (CFD) method, the improved method of considering the roll damping of square moonpool are proposed. The improved method of considering moonpool damping is used in vulnerability assessment for excessive acceleration. The comparative analysis of the Level 1 and Level 2 vulnerability assessment of the excessive acceleration of a ship with moonpool is completed. The influence of moonpool on the vulnerability assessment of excessive acceleration is studied by comparing with the model test results. The results show that the main factor affecting the estimation accuracy of lateral acceleration of the ship is the accuracy of roll amplitude calculation. The existence of moonpool will reduce the roll damping coefficient of the ship. The improved methods proposed in this paper can effectively improve the estimation of lateral acceleration of ships with moonpool in the Level 1 vulnerability criteria and increase the safety margin in the Level 2 vulnerability assessment. In the direct stability assessment, the CFD method can simulate the large-amplitude roll motion of the ship with moonpool and bilge keels, and can capture the strong nonlinear phenomena","PeriodicalId":50106,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2023-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47386354","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}
For a fluid-discharging cantilevered pipe attached with an end-mass, there are two methods to account for the end-mass effect. The first is that the end-mass is considered in the boundary conditions. The second is that the end-mass is included in the equation of motion via a Dirac delta function. As the analytical solution of the linear free vibration model is not available due to the presence of Coriolis force, the eigenfunctions of a beam which satisfy the same boundary conditions are commonly employed in Galerkin method. It has found the first method is incorrect for natural frequency calculation when the internal flow velocity is nonzero. However, the intrinsic mechanism remains to be clarified. This study has demonstrated the eigenfunctions in the first method depends on the end-mass and the orthogonality relations are quite different from that of typical simple beams, based on which a new model is proposed and the prediction compare well with that in the second method. For further validation, the critical internal flow velocity and the onset flutter frequency of a suspended pipe under gravity is computed, which compare well with experimental observations. This study can provide as a workbench for fluid-conveying pipes with various boundary conditions.
{"title":"An Explanation for a Paradox in a Fluid-discharging Cantilevered Pipe attached with an End-mass","authors":"Guixin Zhao, Shuai Meng, Z. Han, Shixiao Fu","doi":"10.1115/1.4056734","DOIUrl":"https://doi.org/10.1115/1.4056734","url":null,"abstract":"\u0000 For a fluid-discharging cantilevered pipe attached with an end-mass, there are two methods to account for the end-mass effect. The first is that the end-mass is considered in the boundary conditions. The second is that the end-mass is included in the equation of motion via a Dirac delta function. As the analytical solution of the linear free vibration model is not available due to the presence of Coriolis force, the eigenfunctions of a beam which satisfy the same boundary conditions are commonly employed in Galerkin method. It has found the first method is incorrect for natural frequency calculation when the internal flow velocity is nonzero. However, the intrinsic mechanism remains to be clarified. This study has demonstrated the eigenfunctions in the first method depends on the end-mass and the orthogonality relations are quite different from that of typical simple beams, based on which a new model is proposed and the prediction compare well with that in the second method. For further validation, the critical internal flow velocity and the onset flutter frequency of a suspended pipe under gravity is computed, which compare well with experimental observations. This study can provide as a workbench for fluid-conveying pipes with various boundary conditions.","PeriodicalId":50106,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2023-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46526141","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}
This work aims to investigate the complex fracture behavior of large opening box girder (LOBG) adopting three-dimensional (3D) finite element method (FEM). A numerical model is developed to simulate the fracture of LOBG under individually or jointly applied torsion and bending loads. The crack damage is introduced into both the side plate and bottom plate of LOBG. The influencing factors including crack lengths, crack angles, crack locations are also emphatically discussed. Besides, the crack growth angles are also predicted during the analysis. The results present that the large opening can generate significant effects on the crack propagation of the side plate crack (SPC) and bottom plate crack (BPC). Under the condition of torsion or hogging, SPC grows more easily than BPC, while BPC is relatively prone to grow under sagging condition. It is also found that the initial crack angles can obviously lower the stress intensity factor (SIF) under bending condition compared to torsion condition. Additionally, the cracks gradually approaching transverse frame are also more likely to induce mode I fracture under torsion condition. These findings from the present study can reveal insights for better understanding of fracture behavior for LOBG.
{"title":"Three-dimensional Fracture Analysis of Large Opening Box Girder with Crack Damage under Bending and Torsion Loads","authors":"Ziya Peng, P. Yang, Yuelin Song, K. Hu","doi":"10.1115/1.4056736","DOIUrl":"https://doi.org/10.1115/1.4056736","url":null,"abstract":"\u0000 This work aims to investigate the complex fracture behavior of large opening box girder (LOBG) adopting three-dimensional (3D) finite element method (FEM). A numerical model is developed to simulate the fracture of LOBG under individually or jointly applied torsion and bending loads. The crack damage is introduced into both the side plate and bottom plate of LOBG. The influencing factors including crack lengths, crack angles, crack locations are also emphatically discussed. Besides, the crack growth angles are also predicted during the analysis. The results present that the large opening can generate significant effects on the crack propagation of the side plate crack (SPC) and bottom plate crack (BPC). Under the condition of torsion or hogging, SPC grows more easily than BPC, while BPC is relatively prone to grow under sagging condition. It is also found that the initial crack angles can obviously lower the stress intensity factor (SIF) under bending condition compared to torsion condition. Additionally, the cracks gradually approaching transverse frame are also more likely to induce mode I fracture under torsion condition. These findings from the present study can reveal insights for better understanding of fracture behavior for LOBG.","PeriodicalId":50106,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2023-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42812974","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}
Ning Fan, Kangping Liao, Qian Wang, Zheng Fang, Hui Zhou
Abstract The study of wind turbine wakes is very important for the layout of offshore wind farms. The technique of regulating the yaw angles of the upstream wind turbine to lessen the influence on the downstream turbines has attracted continual attention in recent years. In this study, the wake interactions between a yaw wind turbine and a downstream wind turbine are investigated using a numerical technique based on the openfoam solver in conjunction with an improved actuator line method. The Gaussian anisotropic body force projection method and the integral velocity sampling method are the two fundamental components of the improvement of the actuator line method. The NREL 5-MW wind turbine benchmark model is used to test the numerical accuracy. The simulation of the wake effects from the upstream turbine in non-yawed conditions that follows has good agreement with the results that have been published in the literature. Finally, this work presents a number of predictions about the power coefficients and wake characteristics of two tandem-arranged wind turbines at various yaw angles based on these precise verification efforts. The results of the analysis in yaw conditions are used to derive the yaw wake characteristics and the optimal yaw angle range. As the yaw angle increases, the total power of the wind turbine increases and then decreases, and the upstream wake area decreases significantly. The total power reaches its maximum at 20–30 deg. The research content of this paper will provide an important reference for wind farm scheduling.
{"title":"A Study of Offshore Wind Turbine Wake Effects in Yaw Conditions Using an Improved Actuator Line Method","authors":"Ning Fan, Kangping Liao, Qian Wang, Zheng Fang, Hui Zhou","doi":"10.1115/1.4056519","DOIUrl":"https://doi.org/10.1115/1.4056519","url":null,"abstract":"Abstract The study of wind turbine wakes is very important for the layout of offshore wind farms. The technique of regulating the yaw angles of the upstream wind turbine to lessen the influence on the downstream turbines has attracted continual attention in recent years. In this study, the wake interactions between a yaw wind turbine and a downstream wind turbine are investigated using a numerical technique based on the openfoam solver in conjunction with an improved actuator line method. The Gaussian anisotropic body force projection method and the integral velocity sampling method are the two fundamental components of the improvement of the actuator line method. The NREL 5-MW wind turbine benchmark model is used to test the numerical accuracy. The simulation of the wake effects from the upstream turbine in non-yawed conditions that follows has good agreement with the results that have been published in the literature. Finally, this work presents a number of predictions about the power coefficients and wake characteristics of two tandem-arranged wind turbines at various yaw angles based on these precise verification efforts. The results of the analysis in yaw conditions are used to derive the yaw wake characteristics and the optimal yaw angle range. As the yaw angle increases, the total power of the wind turbine increases and then decreases, and the upstream wake area decreases significantly. The total power reaches its maximum at 20–30 deg. The research content of this paper will provide an important reference for wind farm scheduling.","PeriodicalId":50106,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135251564","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}
Chern Fong Lee, Christodoulos Tryfonidis, Muk Chen Ong
Abstract An integrated offshore wind and wave energy system is an attractive concept in areas with abundant wind and wave energy resources. The sharing of supporting platform and facilities, e.g., mooring systems, offers significant cost savings. This will effectively lower the levelized cost of energy (LCOE). In the present study, a conceptual design consisting of a braceless semi-submersible floating horizontal axis wind turbine (FHAWT), three flap-type wave energy converters (WECs), as well as a torus (donut-shaped) point absorber-type WEC is proposed. The flap-type WECs harvest wave energy through the flap motion caused by oscillating wave surge, while the torus WEC absorbs wave energy generated from its heaving motion. The absorbed mechanical power of the power take-off (PTO) systems is calculated based on linear damping forces and the motions of the WECs relative to the supporting platform. Hydrodynamic interaction between the WECs and the supporting platform is considered by including the coupling terms in the added mass and potential damping coefficient matrices. A fully coupled aero-servo-hydro-elastic numerical model of the concept is constructed. The feasibility study of the concept is carried out using time-domain simulations. Only operational environmental conditions are simulated based on simultaneous wind and wave hindcast data of a selected offshore site. The effects of the WECs on the wind turbine, platform motions, and WEC power take-off are examined. Based on the power performance of WECs, recommendations are also provided for optimum power absorption.
{"title":"Power Performance and Response Analysis of a Semi-Submersible Wind Turbine Combined With Flap-Type and Torus Wave Energy Converters","authors":"Chern Fong Lee, Christodoulos Tryfonidis, Muk Chen Ong","doi":"10.1115/1.4056520","DOIUrl":"https://doi.org/10.1115/1.4056520","url":null,"abstract":"Abstract An integrated offshore wind and wave energy system is an attractive concept in areas with abundant wind and wave energy resources. The sharing of supporting platform and facilities, e.g., mooring systems, offers significant cost savings. This will effectively lower the levelized cost of energy (LCOE). In the present study, a conceptual design consisting of a braceless semi-submersible floating horizontal axis wind turbine (FHAWT), three flap-type wave energy converters (WECs), as well as a torus (donut-shaped) point absorber-type WEC is proposed. The flap-type WECs harvest wave energy through the flap motion caused by oscillating wave surge, while the torus WEC absorbs wave energy generated from its heaving motion. The absorbed mechanical power of the power take-off (PTO) systems is calculated based on linear damping forces and the motions of the WECs relative to the supporting platform. Hydrodynamic interaction between the WECs and the supporting platform is considered by including the coupling terms in the added mass and potential damping coefficient matrices. A fully coupled aero-servo-hydro-elastic numerical model of the concept is constructed. The feasibility study of the concept is carried out using time-domain simulations. Only operational environmental conditions are simulated based on simultaneous wind and wave hindcast data of a selected offshore site. The effects of the WECs on the wind turbine, platform motions, and WEC power take-off are examined. Based on the power performance of WECs, recommendations are also provided for optimum power absorption.","PeriodicalId":50106,"journal":{"name":"Journal of Offshore Mechanics and Arctic Engineering-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135251563","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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