2022 Vol.36(4)
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2022, 36(4): 509-510.
doi: 10.1007/s13344-022-0050-7
Abstract:
2022, 36(4): 511-531.
doi: 10.1007/s13344-022-0044-5
Abstract:
Offshore oil and gas development plays an important part in the global energy sector. Offshore platforms and flexible pipes are the key equipments in the whole offshore oil and gas development system. Because of the randomness and uncertainty of wave and current loads in the ocean environment, the structural design and mechanical analysis of the marine equipment can be highly complicated. Therefore, this paper reviews the recent works of the theoretical model, numerical simulation, and experimental test in three research areas: hydrodynamic analysis of offshore platforms, structural mechanics analysis of flexible pipe and cable, and monitoring technology of offshore floating structures under marine loads. By analyzing their main research methods and key technical difficulties, this paper provides theoretical basis and technical support for the reliability engineering application of offshore platforms and flexible pipelines. Also, China is relatively backward in the design of marine floating platform, the design, analysis and testing of flexible pipeline and cable, as well as the marine equipment prototype monitoring technology research. Calling for breakthroughs at the earliest possible stage in the above fields, prime research should be focused on and strategic planning should be made to deal with “key areas and stranglehold problems”. It is of great significance for the development of China’s deep-sea energy and resource development of independent technology and on time to achieve the “carbon peak” national strategic objectives.
Offshore oil and gas development plays an important part in the global energy sector. Offshore platforms and flexible pipes are the key equipments in the whole offshore oil and gas development system. Because of the randomness and uncertainty of wave and current loads in the ocean environment, the structural design and mechanical analysis of the marine equipment can be highly complicated. Therefore, this paper reviews the recent works of the theoretical model, numerical simulation, and experimental test in three research areas: hydrodynamic analysis of offshore platforms, structural mechanics analysis of flexible pipe and cable, and monitoring technology of offshore floating structures under marine loads. By analyzing their main research methods and key technical difficulties, this paper provides theoretical basis and technical support for the reliability engineering application of offshore platforms and flexible pipelines. Also, China is relatively backward in the design of marine floating platform, the design, analysis and testing of flexible pipeline and cable, as well as the marine equipment prototype monitoring technology research. Calling for breakthroughs at the earliest possible stage in the above fields, prime research should be focused on and strategic planning should be made to deal with “key areas and stranglehold problems”. It is of great significance for the development of China’s deep-sea energy and resource development of independent technology and on time to achieve the “carbon peak” national strategic objectives.
2022, 36(4): 532-541.
doi: 10.1007/s13344-022-0046-3
Abstract:
The purpose of the present study is to investigate the extreme values of the ice drift speed, which are also considered in the light of the magnitude of the simultaneous wind speed. The relationship between wind speed and ice drift speed is studied. The long-term ice drift data is collected by using local subsurface measurements based on acoustic Doppler current profilers (ADCP) in the Beaufort Sea during the period of 2006?2017. Upward-looking sonars (ULS) are deployed in order to observe the ice thickness as well as to identify events that correspond to open water conditions. The relationship between the ice drift speed and the wind speed is also investigated. It is found that the magnitude of the average ice drift speed is approximately 2.5% of the wind speed during the winter season. Estimation of the extreme values of the ice drift speed is studied by application of the average conditional exceedance rate (ACER) method. It is found that the extreme ice drift speed during the ice melt season (i.e. the summer season) is approximately 20%?30% higher than that during the ice growth season (i.e. the winter season). The extreme ice drift speed can be effectively estimated based on the 2.5% wind speed. Moreover, the extreme ice drift speed can be obtained based on the extreme values of 2.5% of the wind speed based on multiplying with an amplification factor which varies in the range from 1.7 to 2.0 during the growth season, corresponding to increasing return periods of 10, 25, 50 and 100 years.
The purpose of the present study is to investigate the extreme values of the ice drift speed, which are also considered in the light of the magnitude of the simultaneous wind speed. The relationship between wind speed and ice drift speed is studied. The long-term ice drift data is collected by using local subsurface measurements based on acoustic Doppler current profilers (ADCP) in the Beaufort Sea during the period of 2006?2017. Upward-looking sonars (ULS) are deployed in order to observe the ice thickness as well as to identify events that correspond to open water conditions. The relationship between the ice drift speed and the wind speed is also investigated. It is found that the magnitude of the average ice drift speed is approximately 2.5% of the wind speed during the winter season. Estimation of the extreme values of the ice drift speed is studied by application of the average conditional exceedance rate (ACER) method. It is found that the extreme ice drift speed during the ice melt season (i.e. the summer season) is approximately 20%?30% higher than that during the ice growth season (i.e. the winter season). The extreme ice drift speed can be effectively estimated based on the 2.5% wind speed. Moreover, the extreme ice drift speed can be obtained based on the extreme values of 2.5% of the wind speed based on multiplying with an amplification factor which varies in the range from 1.7 to 2.0 during the growth season, corresponding to increasing return periods of 10, 25, 50 and 100 years.
2022, 36(4): 542-552.
doi: 10.1007/s13344-022-0048-1
Abstract:
In the process of deep-sea mining, the liquid-solid flows in the vertical transportation pipeline are very complex. In the present work, an in-house solver MPSDEM-SJTU based on the improved MPS and DEM is developed for the simulation of hydraulic conveying. Firstly, three examples including the multilayer cylinder collapse, the Poiseuille flow and two-phase dam-break are used to validate the precision of the DEM model, the pipe flow model and MPS?DEM coupling model, respectively. Then, the hydraulic conveying with coarse particles in a vertical pipe is simulated. The solid particle distribution is presented and investigated in detail. Finally, the coupling method is successfully applied for the simulation of the liquid?solid flows in a vertical pipe with rotating blades, which shows the stability of the solver under rotating boundary conditions. This fully Lagrangian model is expected to be a new approach for analyzing hydraulic conveying.
In the process of deep-sea mining, the liquid-solid flows in the vertical transportation pipeline are very complex. In the present work, an in-house solver MPSDEM-SJTU based on the improved MPS and DEM is developed for the simulation of hydraulic conveying. Firstly, three examples including the multilayer cylinder collapse, the Poiseuille flow and two-phase dam-break are used to validate the precision of the DEM model, the pipe flow model and MPS?DEM coupling model, respectively. Then, the hydraulic conveying with coarse particles in a vertical pipe is simulated. The solid particle distribution is presented and investigated in detail. Finally, the coupling method is successfully applied for the simulation of the liquid?solid flows in a vertical pipe with rotating blades, which shows the stability of the solver under rotating boundary conditions. This fully Lagrangian model is expected to be a new approach for analyzing hydraulic conveying.
2022, 36(4): 553-564.
doi: 10.1007/s13344-022-0047-2
Abstract:
The subsea suspended manifold designed to replace the traditional foundation structure with the buoys is a new generation subsea production system that can be suspended at a certain height from the seafloor and rapidly recycled by its own buoyancy. Due to complex environmental conditions, its hydrodynamic performance in the splash zone is extremely important for the safety of the whole installation process. In this paper, the mathematical model for the dynamic analysis of the seawater ingress process of the single-layer pre-set horizontal cabin is proposed based on the different center of gravity positions of the buoy. Meanwhile, the theoretical analysis of fiber cable is divided into infinite differential units by the discretization method, and the formulae of the horizontal displacement of the subsea suspended manifold are presented. In addition, the simulations are carried out to verify the rules of the dynamic responses on the subsea suspended manifold system with the consideration of the environmental conditions in the South China Sea. Comparing with the calculated value of the mathematical model of the cabin water ingress, the error of the simulation result by use of FLUENT is about 5.47%. Furthermore, the wave height is greater than the current impact on the lowering manifold system and the azimuth angle of the installation vessel is aligned with the direction of the environmental load.
The subsea suspended manifold designed to replace the traditional foundation structure with the buoys is a new generation subsea production system that can be suspended at a certain height from the seafloor and rapidly recycled by its own buoyancy. Due to complex environmental conditions, its hydrodynamic performance in the splash zone is extremely important for the safety of the whole installation process. In this paper, the mathematical model for the dynamic analysis of the seawater ingress process of the single-layer pre-set horizontal cabin is proposed based on the different center of gravity positions of the buoy. Meanwhile, the theoretical analysis of fiber cable is divided into infinite differential units by the discretization method, and the formulae of the horizontal displacement of the subsea suspended manifold are presented. In addition, the simulations are carried out to verify the rules of the dynamic responses on the subsea suspended manifold system with the consideration of the environmental conditions in the South China Sea. Comparing with the calculated value of the mathematical model of the cabin water ingress, the error of the simulation result by use of FLUENT is about 5.47%. Furthermore, the wave height is greater than the current impact on the lowering manifold system and the azimuth angle of the installation vessel is aligned with the direction of the environmental load.
2022, 36(4): 565-574.
doi: 10.1007/s13344-022-0049-0
Abstract:
Submarine pipelines play an important role in offshore oil and gas development. A touchy issue in pipeline design and application is how to avoid the local collapse of pipelines under external pressure. The pipe diameter-thickness ratio D/t is one of the key factors that determine the local critical collapse pressure of the submarine pipelines. Based on the pipeline collapse experiment and finite element simulation, this paper explores the pressure-bearing capacity of the pipeline under external pressure in a wide range of diameter-thickness ratio D/t. Some interesting and important phenomena have been observed and discussed. In the range of 16<D/t<80, both DNV specification and finite element simulation can predict the collapse pressure of pipeline quite well; in the range of 10<D/t<16, the DNV specification is conservative compared with the experimental results, while the finite element simulation results are slightly larger than the experimental results. Further parameter analysis shows that compared with thin-walled pipes, improving the material grade of thick-walled pipes has higher benefits, and for thin-walled pipes, the ovality f0 should be controlled even more. In addition, combining the results of finite element simulation and model experiment, an empirical formula of critical collapse pressure for thick-walled pipelines is proposed, which is used to correct the error of DNV specification in the range of 10<D/t<16.
Submarine pipelines play an important role in offshore oil and gas development. A touchy issue in pipeline design and application is how to avoid the local collapse of pipelines under external pressure. The pipe diameter-thickness ratio D/t is one of the key factors that determine the local critical collapse pressure of the submarine pipelines. Based on the pipeline collapse experiment and finite element simulation, this paper explores the pressure-bearing capacity of the pipeline under external pressure in a wide range of diameter-thickness ratio D/t. Some interesting and important phenomena have been observed and discussed. In the range of 16<D/t<80, both DNV specification and finite element simulation can predict the collapse pressure of pipeline quite well; in the range of 10<D/t<16, the DNV specification is conservative compared with the experimental results, while the finite element simulation results are slightly larger than the experimental results. Further parameter analysis shows that compared with thin-walled pipes, improving the material grade of thick-walled pipes has higher benefits, and for thin-walled pipes, the ovality f0 should be controlled even more. In addition, combining the results of finite element simulation and model experiment, an empirical formula of critical collapse pressure for thick-walled pipelines is proposed, which is used to correct the error of DNV specification in the range of 10<D/t<16.
2022, 36(4): 575-587.
doi: 10.1007/s13344-022-0051-6
Abstract:
Hydrodynamic numerical simulations are used to conduct structural analyses and inform the design of engineered marine structures. In this paper, a hydrodynamic numerical model of “Nanhai Tiaozhan” (NHTZ) FPS platform was established according to its design specifications. The model was assessed with two sets of field monitoring data representing harsh and conventional sea states. The motion responses of the platform according to the measured data and the hydrodynamic simulation were compared by reviewing their statistical characteristics, distributions, and spectrum characteristics. The comparison showed that the hydrodynamic model could correctly simulate the frequency domain characteristics of the motion responses of the platform. However, the simulation underestimated the reciprocating motions of the floating body and the influence of slow drift on the motion of the platform. Meanwhile, analysis of the monitoring data revealed that the translational degrees of freedom (DOF) and rotational DOF of the platform were coupled, but these coupled motion states were not apparent in the hydrodynamic simulation.
Hydrodynamic numerical simulations are used to conduct structural analyses and inform the design of engineered marine structures. In this paper, a hydrodynamic numerical model of “Nanhai Tiaozhan” (NHTZ) FPS platform was established according to its design specifications. The model was assessed with two sets of field monitoring data representing harsh and conventional sea states. The motion responses of the platform according to the measured data and the hydrodynamic simulation were compared by reviewing their statistical characteristics, distributions, and spectrum characteristics. The comparison showed that the hydrodynamic model could correctly simulate the frequency domain characteristics of the motion responses of the platform. However, the simulation underestimated the reciprocating motions of the floating body and the influence of slow drift on the motion of the platform. Meanwhile, analysis of the monitoring data revealed that the translational degrees of freedom (DOF) and rotational DOF of the platform were coupled, but these coupled motion states were not apparent in the hydrodynamic simulation.
2022, 36(4): 588-600.
doi: 10.1007/s13344-022-0056-1
Abstract:
The gradual advances of offshore oil and gas exploitation and the development tendency of equipment integration have prompted the design of a new type of the high-current composite umbilical to meet development needs. In order to study the mechanical behavior of the high-current composite umbilical (HCCU) and provide design suggestions, a theoretical analysis framework of the tension?torsion coupled behavior of the spirally wound structure is proposed, which focuses more on the radial mechanical behavior. Then, by considering the mechanical and thermal conditions during the operation of HCCU, a semi-analytical method of the tension and torsion stiffness of the high-current composite umbilical considering the temperature effect is established. Furthermore, a practical case of HCCU is given, and the thermal effect on the radial and axial mechanical behaviors are analyzed. It is found that the thermal effect has a significant influence on the radial stiffness, and shows non-linear variation characteristics. Finally, the sensitivity analysis is carried out to study the influence of the design parameter on the stiffness of tension and torsion. The results indicated that the equivalent radial stiffness and helical angle have obvious effect on the tension?torsion coupled stiffness, which can provide reasonable reference for the design of HCCU.
The gradual advances of offshore oil and gas exploitation and the development tendency of equipment integration have prompted the design of a new type of the high-current composite umbilical to meet development needs. In order to study the mechanical behavior of the high-current composite umbilical (HCCU) and provide design suggestions, a theoretical analysis framework of the tension?torsion coupled behavior of the spirally wound structure is proposed, which focuses more on the radial mechanical behavior. Then, by considering the mechanical and thermal conditions during the operation of HCCU, a semi-analytical method of the tension and torsion stiffness of the high-current composite umbilical considering the temperature effect is established. Furthermore, a practical case of HCCU is given, and the thermal effect on the radial and axial mechanical behaviors are analyzed. It is found that the thermal effect has a significant influence on the radial stiffness, and shows non-linear variation characteristics. Finally, the sensitivity analysis is carried out to study the influence of the design parameter on the stiffness of tension and torsion. The results indicated that the equivalent radial stiffness and helical angle have obvious effect on the tension?torsion coupled stiffness, which can provide reasonable reference for the design of HCCU.
2022, 36(4): 601-613.
doi: 10.1007/s13344-022-0052-5
Abstract:
The cross-flow (CF) vortex-induced vibration (VIV) of a deepwater steep wave riser (SWR) subjected to uniform or shear flow loads is investigated numerically. The model is based on a three-dimensional (3D) nonlinear elastic rod theory coupled with a wake oscillator model. In this numerical simulation, the nonlinear motion equations of the riser with large deformation features are established in a global coordinate system to avoid the transformation between global and local coordinate systems, and are discretized with the time-domain finite element method (FEM). A wake-oscillator model is employed to study the vortex shedding, and the lift force generated by the wake flow is described in a van der Pol equation. A Newmark-β iterative scheme is used to solve their coupling equation for the VIV response of the SWR. The developed model is validated against the existing experimental results for the VIV response of the top-tension riser (TTR). Then, the numerical simulations are executed to determine VIV characteristics of the SWR. The effects of both flow velocity and the spanwise length of the flow field on the drag coefficient in the inline (IL) direction and the lift coefficient in the CF direction are investigated systematically. The results indicate that compared with TTR, the low frequency and multi-modal vibration are the main components of the SWR due to the large deformation and flexible characteristics. For shear flow, the multi-frequency resonance dominates the VIV response of the SWR, especially at the hang-off segment.
The cross-flow (CF) vortex-induced vibration (VIV) of a deepwater steep wave riser (SWR) subjected to uniform or shear flow loads is investigated numerically. The model is based on a three-dimensional (3D) nonlinear elastic rod theory coupled with a wake oscillator model. In this numerical simulation, the nonlinear motion equations of the riser with large deformation features are established in a global coordinate system to avoid the transformation between global and local coordinate systems, and are discretized with the time-domain finite element method (FEM). A wake-oscillator model is employed to study the vortex shedding, and the lift force generated by the wake flow is described in a van der Pol equation. A Newmark-β iterative scheme is used to solve their coupling equation for the VIV response of the SWR. The developed model is validated against the existing experimental results for the VIV response of the top-tension riser (TTR). Then, the numerical simulations are executed to determine VIV characteristics of the SWR. The effects of both flow velocity and the spanwise length of the flow field on the drag coefficient in the inline (IL) direction and the lift coefficient in the CF direction are investigated systematically. The results indicate that compared with TTR, the low frequency and multi-modal vibration are the main components of the SWR due to the large deformation and flexible characteristics. For shear flow, the multi-frequency resonance dominates the VIV response of the SWR, especially at the hang-off segment.
2022, 36(4): 614-628.
doi: 10.1007/s13344-022-0054-3
Abstract:
This study explores how parametric uncertainties in the production affect failure tensile loads of reinforced thermoplastic pipes (RTPs) under combined loading conditions. The stress distributions in RTPs are examined with three-dimensional (3D) elasticity theory, and the analytical micromechanics of composites are evaluated. To evaluate the failure mechanisms for RTPs, 3D Hashin–Yeh failure criteria are combined with the damage evolution model to establish a progressive failure model. The theoretical model has been validated through numerical simulations and axial tensile tests data. To analyze how randomness of relevant parameters affects the first-ply failure (FPF) tensile load and final failure (FF) tensile load in RTPs, many samples are produced with the Monte–Carlo approach. The stochastic analysis results are statistically evaluated through the Weibull probability density distribution function. For the randomness of production parameters, the failure tensile load of RTPs fluctuates near the mean value. As the ply number at the reinforced layer increases, the dispersion of failure tensile load increases, with a high probability that the FPF tensile load of RTPs is lower than the mean value.
This study explores how parametric uncertainties in the production affect failure tensile loads of reinforced thermoplastic pipes (RTPs) under combined loading conditions. The stress distributions in RTPs are examined with three-dimensional (3D) elasticity theory, and the analytical micromechanics of composites are evaluated. To evaluate the failure mechanisms for RTPs, 3D Hashin–Yeh failure criteria are combined with the damage evolution model to establish a progressive failure model. The theoretical model has been validated through numerical simulations and axial tensile tests data. To analyze how randomness of relevant parameters affects the first-ply failure (FPF) tensile load and final failure (FF) tensile load in RTPs, many samples are produced with the Monte–Carlo approach. The stochastic analysis results are statistically evaluated through the Weibull probability density distribution function. For the randomness of production parameters, the failure tensile load of RTPs fluctuates near the mean value. As the ply number at the reinforced layer increases, the dispersion of failure tensile load increases, with a high probability that the FPF tensile load of RTPs is lower than the mean value.
2022, 36(4): 629-637.
doi: 10.1007/s13344-022-0053-4
Abstract:
Through the development of marine energy, marine cables are the key equipment for transmission of electrical energy between surface platforms and underwater facilities. Fatigue failure is a critical failure mode of marine cables. The bending performance of the cable conductor has a major influence on both bending and fatigue performances of the overall cable structure. To study the influence of different types of the conductor cross-section on the bending performances of marine cable conductors, three types of copper conductors with the same cross-sectional area, i.e., noncompressed round, compressed round, and shaped wire conductors, were selected. The experimental results demonstrated that the cross-section type significantly affects the bending performances of copper conductors. In particular, the bending stiffness of the shaped wire conductor is the highest among the three conductor types. Four key evaluation parameters, i.e., the bending stiffness, maximum bending moment, envelope area, and engineering critical slip point, were selected to compare and analyze the bending hysteresis curves of the three copper conductors. The differences in the key evaluation parameters were analyzed based on the structural dimensional parameters, processing methods, and classical bending stiffness theoretical models of the three copper conductor types. The results provide an important theoretical guidance for the structural design and engineering applications of marine cable conductors.
Through the development of marine energy, marine cables are the key equipment for transmission of electrical energy between surface platforms and underwater facilities. Fatigue failure is a critical failure mode of marine cables. The bending performance of the cable conductor has a major influence on both bending and fatigue performances of the overall cable structure. To study the influence of different types of the conductor cross-section on the bending performances of marine cable conductors, three types of copper conductors with the same cross-sectional area, i.e., noncompressed round, compressed round, and shaped wire conductors, were selected. The experimental results demonstrated that the cross-section type significantly affects the bending performances of copper conductors. In particular, the bending stiffness of the shaped wire conductor is the highest among the three conductor types. Four key evaluation parameters, i.e., the bending stiffness, maximum bending moment, envelope area, and engineering critical slip point, were selected to compare and analyze the bending hysteresis curves of the three copper conductors. The differences in the key evaluation parameters were analyzed based on the structural dimensional parameters, processing methods, and classical bending stiffness theoretical models of the three copper conductor types. The results provide an important theoretical guidance for the structural design and engineering applications of marine cable conductors.
2022, 36(4): 638-648.
doi: 10.1007/s13344-022-0057-0
Abstract:
Formation subsidence is inevitable during marine hydrate decomposition, and the consequent casing deformation seriously threatens the security of sustainable hydrate production. Owing to insufficient observed data of formation subsidence in field, displacement boundary condition of casing is undetermined. Thus the conventional static methods are inapplicable for the calculation of casing deformation in hydrate production well. The present work aims at proposing an approach to investigate dynamic deformation of the casing during hydrate production. In the proposed methodology, based on the movement theory of hydrate decomposition front, hydrate decomposition process can be simulated, in which hydrate reservoir strength formation subsidence showed time-dependent characteristics. By considering the actual interactions among casing, cement and formation, three models of hydrate production well are developed to reveal the static and dynamic deformation mechanisms of the casing. The application of the proposed methodology is demonstrated through a case study. Results show that buckling deformation and bending deformation of casing reduce the passing ability of downhole tools in deformed casing by 4.2% and 7.5%, respectively. With the progress of hydrate production, buckling deformation will increase obviously, while a little increase of bending deformation will occur, as the formation slippage induced by formation inclination is much larger than that caused by hydrate decomposition. The proposed approach can provide theoretical reference for improving casing integrity of marine hydrate production.
Formation subsidence is inevitable during marine hydrate decomposition, and the consequent casing deformation seriously threatens the security of sustainable hydrate production. Owing to insufficient observed data of formation subsidence in field, displacement boundary condition of casing is undetermined. Thus the conventional static methods are inapplicable for the calculation of casing deformation in hydrate production well. The present work aims at proposing an approach to investigate dynamic deformation of the casing during hydrate production. In the proposed methodology, based on the movement theory of hydrate decomposition front, hydrate decomposition process can be simulated, in which hydrate reservoir strength formation subsidence showed time-dependent characteristics. By considering the actual interactions among casing, cement and formation, three models of hydrate production well are developed to reveal the static and dynamic deformation mechanisms of the casing. The application of the proposed methodology is demonstrated through a case study. Results show that buckling deformation and bending deformation of casing reduce the passing ability of downhole tools in deformed casing by 4.2% and 7.5%, respectively. With the progress of hydrate production, buckling deformation will increase obviously, while a little increase of bending deformation will occur, as the formation slippage induced by formation inclination is much larger than that caused by hydrate decomposition. The proposed approach can provide theoretical reference for improving casing integrity of marine hydrate production.
2022, 36(4): 649-657.
doi: 10.1007/s13344-022-0045-4
Abstract:
Floating offshore wind turbines (FOWTs) are a promising offshore renewable energy harvesting facility but requesting multiple-disciplinary analysis for their dynamic performance predictions. However, engineering-fidelity level tools and the empirical parameters pose challenges due to the strong nonlinear coupling effects of FOWTs. A novel method, named SADA, was proposed by Chen and Hu (2021) for optimizing the design and dynamic performance prediction of FOWTs in combination with AI technology. In the SADA method, the concept of Key Disciplinary Parameters (KDPs) is also proposed, and it is of crucial importance in the SADA method. The purpose of this paper is to make an in-depth investigation of the characters of KDPs and the internal correlations between different KDPs in the dynamic performance prediction of FOWTs. Firstly, a brief description of SADA is given, and the basin experimental data are used to conduct the training process of SADA. Secondly, categories and boundary conditions of KDPs are introduced. Three types of KDPs are given, and different boundary conditions are used to analyze KDPs. The results show that the wind and current in Environmental KDPs are strongly correlated with the percentage difference of dynamic response rather than that by wave parameters. In general, the optimization results of SADA consider the specific basin environment and the coupling results between different KDPs help the designers further understand the factors that have a more significant impact on the FOWTs system in a specific domain.
Floating offshore wind turbines (FOWTs) are a promising offshore renewable energy harvesting facility but requesting multiple-disciplinary analysis for their dynamic performance predictions. However, engineering-fidelity level tools and the empirical parameters pose challenges due to the strong nonlinear coupling effects of FOWTs. A novel method, named SADA, was proposed by Chen and Hu (2021) for optimizing the design and dynamic performance prediction of FOWTs in combination with AI technology. In the SADA method, the concept of Key Disciplinary Parameters (KDPs) is also proposed, and it is of crucial importance in the SADA method. The purpose of this paper is to make an in-depth investigation of the characters of KDPs and the internal correlations between different KDPs in the dynamic performance prediction of FOWTs. Firstly, a brief description of SADA is given, and the basin experimental data are used to conduct the training process of SADA. Secondly, categories and boundary conditions of KDPs are introduced. Three types of KDPs are given, and different boundary conditions are used to analyze KDPs. The results show that the wind and current in Environmental KDPs are strongly correlated with the percentage difference of dynamic response rather than that by wave parameters. In general, the optimization results of SADA consider the specific basin environment and the coupling results between different KDPs help the designers further understand the factors that have a more significant impact on the FOWTs system in a specific domain.
Liang YANG,
Miao-er LIU,
Yun LIU,
Fang-qiu LI,
Jia-kun FAN,
Fu-peng LIU,
Zhao-kuan LU,
Jian-ye YANG,
Jun YAN
2022, 36(4): 658-665.
doi: 10.1007/s13344-022-0058-z
Abstract:
This work presents a numerical investigation of the thermal–fluid–structure coupling behavior of the liquid natural gas (LNG) transported in the flexible corrugated cryogenic hose. A three-dimensional model of the corrugated hose structure composed of multiple layers of different materials is established and coupled with turbulent LNG flow and heat transfer models in the commercial software ANSYS Workbench. The flow transport behavior, heat transfer across the hose layers, and structural response caused by the flow are analyzed. Parametric studies are performed to evaluate the impacts of inlet flow rate and thermal conductivity of insulation material on the temperature and structural stress of the corrugated hose. The study found that, compared with a regular operating condition, higher inlet flow velocities not only suppress the heat gain of the LNG but also lower the flow-induced structural stress. The insulation layer exhibits excellent performance in maintaining the temperature at the fluid–structure interface, showing little temperature change with respect to material thermal conductivity and ambient temperature. The simulation results may contribute to the research and design of the flexible corrugated cryogenic hoses and provide guidance for safer and more efficient field operations.
This work presents a numerical investigation of the thermal–fluid–structure coupling behavior of the liquid natural gas (LNG) transported in the flexible corrugated cryogenic hose. A three-dimensional model of the corrugated hose structure composed of multiple layers of different materials is established and coupled with turbulent LNG flow and heat transfer models in the commercial software ANSYS Workbench. The flow transport behavior, heat transfer across the hose layers, and structural response caused by the flow are analyzed. Parametric studies are performed to evaluate the impacts of inlet flow rate and thermal conductivity of insulation material on the temperature and structural stress of the corrugated hose. The study found that, compared with a regular operating condition, higher inlet flow velocities not only suppress the heat gain of the LNG but also lower the flow-induced structural stress. The insulation layer exhibits excellent performance in maintaining the temperature at the fluid–structure interface, showing little temperature change with respect to material thermal conductivity and ambient temperature. The simulation results may contribute to the research and design of the flexible corrugated cryogenic hoses and provide guidance for safer and more efficient field operations.
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