Lariuss Zago, A. Kawano, A. Simos, Rodolfo T. Gonçalves
The continuous monitoring of sea states is important for many activities, from gathering oceanographic data to the planning of ship operations. There are several means to infer sea conditions, with variable levels of accuracy. Among these, the methods based on on-board measurements of vessel motions have been addressed by many researchers, attracted mainly by its practicality regarding installation and maintenance issues. However, the idea of using vessels as wave sensor also brings restrictions, mainly associated with the filtering of short waves that causes no significant motions of the hull, and, furthermore, the vessel speed introduces considerable complexity in the mathematical inference procedure. A significant part of this complexity is associated with the triple-value problem related to stern wave conditions. In the context of a research that addresses an alternative method for the parametric estimation of sea waves based on vessels with forward speed, this article deals with the problem of devising a proper parametric representation of the wave energy distribution as seen in the ship’s reference frame, i.e., the encounter wave spectrum. A Weibull-distribution parametrization is proposed, for its ability to handle the significant variations of encounter wave spectrum shapes. Analyses performed for several combinations of wave directions, peak frequencies and vessel’s speed show that this approach is indeed capable of providing proper representation of the spectral shapes based on few parameters, both for bow and stern waves.
{"title":"A Weibull Distribution-Based Parametrization for Encounter Wave Spectra","authors":"Lariuss Zago, A. Kawano, A. Simos, Rodolfo T. Gonçalves","doi":"10.1115/omae2022-79264","DOIUrl":"https://doi.org/10.1115/omae2022-79264","url":null,"abstract":"\u0000 The continuous monitoring of sea states is important for many activities, from gathering oceanographic data to the planning of ship operations. There are several means to infer sea conditions, with variable levels of accuracy. Among these, the methods based on on-board measurements of vessel motions have been addressed by many researchers, attracted mainly by its practicality regarding installation and maintenance issues. However, the idea of using vessels as wave sensor also brings restrictions, mainly associated with the filtering of short waves that causes no significant motions of the hull, and, furthermore, the vessel speed introduces considerable complexity in the mathematical inference procedure. A significant part of this complexity is associated with the triple-value problem related to stern wave conditions. In the context of a research that addresses an alternative method for the parametric estimation of sea waves based on vessels with forward speed, this article deals with the problem of devising a proper parametric representation of the wave energy distribution as seen in the ship’s reference frame, i.e., the encounter wave spectrum. A Weibull-distribution parametrization is proposed, for its ability to handle the significant variations of encounter wave spectrum shapes. Analyses performed for several combinations of wave directions, peak frequencies and vessel’s speed show that this approach is indeed capable of providing proper representation of the spectral shapes based on few parameters, both for bow and stern waves.","PeriodicalId":408227,"journal":{"name":"Volume 5A: Ocean Engineering","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133615872","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Nian-Qin Zhang, Longfei Xiao, Handi Wei, X. Teng, Yi-zhi Guo
Semi-submersible platforms have been widely used in offshore oil and gas exploitation due to their excellent performance, but wave impacts in extreme sea states remain a major concern. For the design of offshore structures with sufficient structural capacity, scholars have pointed out the wave pressure impulse obtained by time integration is more crucial compared with the peak impact pressure. In this study, wave basin experiments were carried out under a series of irregular waves to study the spatial variations of pressure impulse on a semi-submersible. To capture more wave impact events and get more accurate local impact pressures, a large number of impact load measurement units were compactly installed on two adjacent surfaces at the corner of test model. The probability statistical method is adopted to analyze the nonlinear features and spatial variations. The results show that the pressure impulse on a semi-submersible in irregular waves has strong variability and its spatial distribution presents local concentration features. It is found that wave impacts on the column are more serious and the variations of pressure impulse on the column are greater than that on the side of deck box under head sea state. Spatial variations of pressure impulse on a semi-submersible are severely affected by significant wave height Hs and spectral peak period Tp of irregular waves. Meanwhile, the number of wave seeds used in model tests have a decisive influence on the estimation and spatial variation of wave pressure impulses. The perspectives given in this study may provide references for the structure design of semi-submersible platforms and lay a foundation for improving the laboratory experiment of wave impacts.
{"title":"Spatial Distribution of Impact Pressure Impulse on a Semi-Submersible in Irregular Waves","authors":"Nian-Qin Zhang, Longfei Xiao, Handi Wei, X. Teng, Yi-zhi Guo","doi":"10.1115/omae2022-80037","DOIUrl":"https://doi.org/10.1115/omae2022-80037","url":null,"abstract":"\u0000 Semi-submersible platforms have been widely used in offshore oil and gas exploitation due to their excellent performance, but wave impacts in extreme sea states remain a major concern. For the design of offshore structures with sufficient structural capacity, scholars have pointed out the wave pressure impulse obtained by time integration is more crucial compared with the peak impact pressure. In this study, wave basin experiments were carried out under a series of irregular waves to study the spatial variations of pressure impulse on a semi-submersible. To capture more wave impact events and get more accurate local impact pressures, a large number of impact load measurement units were compactly installed on two adjacent surfaces at the corner of test model. The probability statistical method is adopted to analyze the nonlinear features and spatial variations. The results show that the pressure impulse on a semi-submersible in irregular waves has strong variability and its spatial distribution presents local concentration features. It is found that wave impacts on the column are more serious and the variations of pressure impulse on the column are greater than that on the side of deck box under head sea state. Spatial variations of pressure impulse on a semi-submersible are severely affected by significant wave height Hs and spectral peak period Tp of irregular waves. Meanwhile, the number of wave seeds used in model tests have a decisive influence on the estimation and spatial variation of wave pressure impulses. The perspectives given in this study may provide references for the structure design of semi-submersible platforms and lay a foundation for improving the laboratory experiment of wave impacts.","PeriodicalId":408227,"journal":{"name":"Volume 5A: Ocean Engineering","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123507967","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The addition of a trailing edge flap is an effective way to enhance the lift generated by marine rudders. This is achieved through camber being introduced into the foil section when the flap is deflected. But the strong curvature in the flow around the flap’s leading edge makes it prone to early flow separation and increased drag. Leading-edge tubercles offer a means to control flow separation whilst improving lifting performance at post-stall angles of attack (AOA). Therefore, this study aims to investigate the tubercle leading edge’s (TLE) ability to improve the hydrodynamic performance of a flapped rudder. A finite-span reference rudder with a 20% trailing-edge flap and its TLE modification were numerically analysed using Detached Eddy Simulations (DES) for fully turbulent flow at a Reynolds number of 1.15 × 106. Flow separation severity and progression were controlled and minimised through the TLE modifications. As a result, the TLE rudder produced up to 15% higher maximum lift and up to 25% more post-stall lift. The rudder efficiency also improved for various rudder and flap angle combinations.
{"title":"Leading-Edge Tubercles Applied Onto a Flapped Rudder","authors":"Moritz Troll, Weichao Shi, Callum Stark","doi":"10.1115/omae2022-80807","DOIUrl":"https://doi.org/10.1115/omae2022-80807","url":null,"abstract":"\u0000 The addition of a trailing edge flap is an effective way to enhance the lift generated by marine rudders. This is achieved through camber being introduced into the foil section when the flap is deflected. But the strong curvature in the flow around the flap’s leading edge makes it prone to early flow separation and increased drag. Leading-edge tubercles offer a means to control flow separation whilst improving lifting performance at post-stall angles of attack (AOA). Therefore, this study aims to investigate the tubercle leading edge’s (TLE) ability to improve the hydrodynamic performance of a flapped rudder. A finite-span reference rudder with a 20% trailing-edge flap and its TLE modification were numerically analysed using Detached Eddy Simulations (DES) for fully turbulent flow at a Reynolds number of 1.15 × 106.\u0000 Flow separation severity and progression were controlled and minimised through the TLE modifications. As a result, the TLE rudder produced up to 15% higher maximum lift and up to 25% more post-stall lift. The rudder efficiency also improved for various rudder and flap angle combinations.","PeriodicalId":408227,"journal":{"name":"Volume 5A: Ocean Engineering","volume":"108 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125238361","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Seunghyun Kim, S. Kinnas, Ray Thomas Grebstad, Jahn Terje Johannessen
In this paper, a boundary element method (BEM) is used to predict the unsteady performance of ducted propellers in open water and ship behind conditions. The model propeller adopted includes the non-axisymmetric duct appendages (e.g., gearbox, brackets, and vertical structure connected to the hub), which induce severe shedding vortices on the propeller plane. This study thus investigates the effects of separation from the duct appendages as well as the upstream hull on the unsteady ducted propeller performance under different loading conditions. To improve the accuracy of a potential flow solver for highly viscous problems with separated flow near a blunt body, the present method is coupled with a viscous Reynolds-Averaged Navier-Stokes (RANS) solver. The former solves the ducted propeller problem to produce the propeller-induced flow field and body forces, with which the latter solves the total flow field based on a finite volume method. This approach is implemented in an iterative manner until the predicted 3D effective wake on the propeller surface becomes fully converged. An automated interface is developed to facilitate this process. A complete analysis of the propeller performance (i.e., predicted effective wake, flow-field, unsteady forces, and circulations on the blade) is presented at various operating conditions to investigate how the flow field inside and outside the nozzle is influenced by the viscous interaction among the incoming flow, propeller, its appendages, and upstream hull. For the sake of validation, the predicted results are compared with experimental measurements and results from unsteady full-blown RANS simulations. The presented results show satisfactory agreement among the results from different approaches, which makes the BEM/RANS coupling scheme adequate and computationally efficient for practical applications.
本文采用边界元法(BEM)对导管式螺旋桨在开阔水域和船后工况下的非定常性能进行了预测。所采用的模型螺旋桨包括非轴对称风道附件(如齿轮箱、托架、与轮毂连接的垂直结构)，这些附件在螺旋桨平面上产生严重的脱落涡。因此，本文研究了不同载荷条件下，与管道附属物分离以及上游船体分离对非定常导管螺旋桨性能的影响。为了提高钝体附近具有分离流的高粘性问题的势流求解器的精度，将该方法与粘性reynolds - average Navier-Stokes (RANS)求解器相结合。前者解决了导管式螺旋桨问题，产生了螺旋桨诱导的流场和体力，后者基于有限体积法求解了总流场。该方法以迭代的方式实现，直到预测的螺旋桨表面三维有效尾迹完全收敛。开发了一个自动化界面来促进这一过程。对不同工况下的螺旋桨性能(即预测的有效尾迹、流场、非定常力和叶片上的循环)进行了完整的分析，以研究来流、螺旋桨及其附属物和上游船体之间的粘性相互作用对喷管内外流场的影响。为了验证预测结果，将预测结果与实验测量结果和非定常全面RANS模拟结果进行了比较。结果表明，不同方法的计算结果具有较好的一致性，表明BEM/RANS耦合方案具有较好的计算效率。
{"title":"Hydrodynamic Analysis of a Triple Thruster Unit Via a BEM/RANS Interactive Method","authors":"Seunghyun Kim, S. Kinnas, Ray Thomas Grebstad, Jahn Terje Johannessen","doi":"10.1115/omae2022-81026","DOIUrl":"https://doi.org/10.1115/omae2022-81026","url":null,"abstract":"\u0000 In this paper, a boundary element method (BEM) is used to predict the unsteady performance of ducted propellers in open water and ship behind conditions. The model propeller adopted includes the non-axisymmetric duct appendages (e.g., gearbox, brackets, and vertical structure connected to the hub), which induce severe shedding vortices on the propeller plane. This study thus investigates the effects of separation from the duct appendages as well as the upstream hull on the unsteady ducted propeller performance under different loading conditions. To improve the accuracy of a potential flow solver for highly viscous problems with separated flow near a blunt body, the present method is coupled with a viscous Reynolds-Averaged Navier-Stokes (RANS) solver. The former solves the ducted propeller problem to produce the propeller-induced flow field and body forces, with which the latter solves the total flow field based on a finite volume method. This approach is implemented in an iterative manner until the predicted 3D effective wake on the propeller surface becomes fully converged. An automated interface is developed to facilitate this process. A complete analysis of the propeller performance (i.e., predicted effective wake, flow-field, unsteady forces, and circulations on the blade) is presented at various operating conditions to investigate how the flow field inside and outside the nozzle is influenced by the viscous interaction among the incoming flow, propeller, its appendages, and upstream hull. For the sake of validation, the predicted results are compared with experimental measurements and results from unsteady full-blown RANS simulations. The presented results show satisfactory agreement among the results from different approaches, which makes the BEM/RANS coupling scheme adequate and computationally efficient for practical applications.","PeriodicalId":408227,"journal":{"name":"Volume 5A: Ocean Engineering","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126101477","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The oil and gas companies extended their activities in the offshore area of the North Seas. The presence of extreme environmental waves imparts extra risks to the operations of the offshore fixed and floating structures in these areas. The operation and safety of these offshore structures are considerably disturbed during the propagation of large waves over the region. The Newfoundland coast experienced very high waves during an intense ever storm in 2018 that brought waves with very large wave heights at various locations. This paper reports the loadings of such high waves on the shaft of a Gravity-Based Structure (GBS). A 3D non-linear dispersive mass, momentum, and energy model (MME) with second-order in wave amplitudes, and OrcaFlex™, a commercial numerical tool are used for the simulation of loads on the structure. The 3D numerical model describes the characteristics of the wavefield in terms of mass, momentum, and energy flux conservation equations. OrcaFlex™ is a 3D non-linear time-domain finite element implicit and explicit software that uses lumped mass elements to simplify equations, has diffraction capability, and makes the computation efficient. In the simulations, parameters for incident wave conditions are varied systematically to study various cases and data comparisons between the two numerical simulators are made. The geometry of the GBS was kept constant. The water depth is assumed to be 80m and the shaft length is 95m with a diameter of 30m. The simulation is carried out for 3 hours in each case. New data and information that would be produced from this work are important for possible use in the design method of a GBS and thus increase structural and operational safety exclusively in the harsh environment or in the existence of freak waves.
{"title":"Evaluation of Hydrodynamic Loads on a Concrete Gravity-Based Offshore Structure in Extreme Waves","authors":"M. Zaman, A. Akinturk","doi":"10.1115/omae2022-78578","DOIUrl":"https://doi.org/10.1115/omae2022-78578","url":null,"abstract":"\u0000 The oil and gas companies extended their activities in the offshore area of the North Seas. The presence of extreme environmental waves imparts extra risks to the operations of the offshore fixed and floating structures in these areas. The operation and safety of these offshore structures are considerably disturbed during the propagation of large waves over the region. The Newfoundland coast experienced very high waves during an intense ever storm in 2018 that brought waves with very large wave heights at various locations. This paper reports the loadings of such high waves on the shaft of a Gravity-Based Structure (GBS). A 3D non-linear dispersive mass, momentum, and energy model (MME) with second-order in wave amplitudes, and OrcaFlex™, a commercial numerical tool are used for the simulation of loads on the structure. The 3D numerical model describes the characteristics of the wavefield in terms of mass, momentum, and energy flux conservation equations. OrcaFlex™ is a 3D non-linear time-domain finite element implicit and explicit software that uses lumped mass elements to simplify equations, has diffraction capability, and makes the computation efficient. In the simulations, parameters for incident wave conditions are varied systematically to study various cases and data comparisons between the two numerical simulators are made. The geometry of the GBS was kept constant. The water depth is assumed to be 80m and the shaft length is 95m with a diameter of 30m. The simulation is carried out for 3 hours in each case.\u0000 New data and information that would be produced from this work are important for possible use in the design method of a GBS and thus increase structural and operational safety exclusively in the harsh environment or in the existence of freak waves.","PeriodicalId":408227,"journal":{"name":"Volume 5A: Ocean Engineering","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129445670","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The accurate prediction of ship maneuvering characteristics requires accurate representation of the forces on the propellers and rudders. Computational Fluid Dynamics (CFD) can accurately predict the maneuvering characteristics of a vessel, but the expense is dominated by the discretization of the propellers, and long-time simulations are too expensive for practical use. Propeller and rudder models can reduce the computational cost, but can also reduce the accuracy. The objective of this work is to accurately model the Office of Naval Research (ONR) Tumblehome performing both turning circle and zig-zag maneuvers with high-fidelity data-driven propeller and rudder models. The use of the data-driven propeller and rudder models significantly reduces the computational cost of performing a maneuver. The forces of the propeller and rudder are calculated as a function of the propeller revolution rate, the rigid body velocity of the vessel, and the rudder angle. The propeller and rudder models are trained with a select number of CFD simulations with the discretized propeller and rudder operating in the behind condition. The propeller and rudder models maintain the accuracy of using a discretized propeller and rudder with respect to CFD simulations used for validation. The models calculate the multi-degree of freedom force acting on the propellers and rudders of the vessel. For comparison, the maneuvering characteristics of the vessel are also analyzed with a simplified body-force propeller and a Whicker and Fehlner rudder model.
{"title":"Data-Driven Propeller and Rudder Modeling for Maneuvering Analysis of the ONR Tumblehome","authors":"Bradford G. Knight, K. Silva, K. Maki","doi":"10.1115/omae2022-79139","DOIUrl":"https://doi.org/10.1115/omae2022-79139","url":null,"abstract":"\u0000 The accurate prediction of ship maneuvering characteristics requires accurate representation of the forces on the propellers and rudders. Computational Fluid Dynamics (CFD) can accurately predict the maneuvering characteristics of a vessel, but the expense is dominated by the discretization of the propellers, and long-time simulations are too expensive for practical use. Propeller and rudder models can reduce the computational cost, but can also reduce the accuracy. The objective of this work is to accurately model the Office of Naval Research (ONR) Tumblehome performing both turning circle and zig-zag maneuvers with high-fidelity data-driven propeller and rudder models. The use of the data-driven propeller and rudder models significantly reduces the computational cost of performing a maneuver. The forces of the propeller and rudder are calculated as a function of the propeller revolution rate, the rigid body velocity of the vessel, and the rudder angle. The propeller and rudder models are trained with a select number of CFD simulations with the discretized propeller and rudder operating in the behind condition. The propeller and rudder models maintain the accuracy of using a discretized propeller and rudder with respect to CFD simulations used for validation. The models calculate the multi-degree of freedom force acting on the propellers and rudders of the vessel. For comparison, the maneuvering characteristics of the vessel are also analyzed with a simplified body-force propeller and a Whicker and Fehlner rudder model.","PeriodicalId":408227,"journal":{"name":"Volume 5A: Ocean Engineering","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131135248","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Khanh Q. Bui, L. Perera, J. Emblemsvåg, Halvor Schøyen
Stricter regulations and ambitious targets regarding air emissions from ships have led the shipping industry to a tipping point necessitating disruptive technologies for green and ecological operation. This study introduces a dual-fuel engine innovation with ultra-high energy conversion efficiency, thereby reducing exhaust gas emissions. However, the total cost performance of such an innovation throughout its long lifespan can be a matter of concern for decision makers (i.e. ship owners) if they decide to retrofit their existing fleet. The purpose of this study is to provide insights into the economic performance of such an innovative dual-fuel engine when it is utilized as the main propulsion system. From a cradle-to-grave perspective ranging from construction, operation, maintenance to end-of-life, the life-cycle costing (LCC) framework is proposed to evaluate the long-term cost performance of the dual-fuel engine with that of a conventional diesel engine. By using the net present cost (NPC) as an evaluation indicator, the research results reveal that the dual-fuel engine is considered as a cost-effective option except for the high fuel price differential scenario, meaning that fuel prices are the most critical factor for ship owners. In addition, the environmental impact of these engines is included in the evaluation to show that 33% reduction in emissions of carbon dioxide (CO2) can be achieved when running the dual-fuel engine, compared to the diesel engine. The proposed framework could conceivably be beneficial in selecting marine engine innovation that takes not only the environmental impact but also the economic performance into consideration.
{"title":"Life-Cycle Cost Analysis on a Marine Engine Innovation for Retrofit: A Comparative Study","authors":"Khanh Q. Bui, L. Perera, J. Emblemsvåg, Halvor Schøyen","doi":"10.1115/omae2022-79488","DOIUrl":"https://doi.org/10.1115/omae2022-79488","url":null,"abstract":"\u0000 Stricter regulations and ambitious targets regarding air emissions from ships have led the shipping industry to a tipping point necessitating disruptive technologies for green and ecological operation. This study introduces a dual-fuel engine innovation with ultra-high energy conversion efficiency, thereby reducing exhaust gas emissions. However, the total cost performance of such an innovation throughout its long lifespan can be a matter of concern for decision makers (i.e. ship owners) if they decide to retrofit their existing fleet. The purpose of this study is to provide insights into the economic performance of such an innovative dual-fuel engine when it is utilized as the main propulsion system. From a cradle-to-grave perspective ranging from construction, operation, maintenance to end-of-life, the life-cycle costing (LCC) framework is proposed to evaluate the long-term cost performance of the dual-fuel engine with that of a conventional diesel engine. By using the net present cost (NPC) as an evaluation indicator, the research results reveal that the dual-fuel engine is considered as a cost-effective option except for the high fuel price differential scenario, meaning that fuel prices are the most critical factor for ship owners. In addition, the environmental impact of these engines is included in the evaluation to show that 33% reduction in emissions of carbon dioxide (CO2) can be achieved when running the dual-fuel engine, compared to the diesel engine. The proposed framework could conceivably be beneficial in selecting marine engine innovation that takes not only the environmental impact but also the economic performance into consideration.","PeriodicalId":408227,"journal":{"name":"Volume 5A: Ocean Engineering","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124584343","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The fuel type selection according to optimal pathway from extraction of a raw material (feedstock) to its processing to transportation and finally its use in marine engines (well to wheel) based on the cost and emission criteria is the main motivation factor to conduct the current investigation. The undertaken procedure has been customized based on the available data (ship/bunker route and mileage, the ship powertrain system, etc.) of the shipping industry under the SeaTech H2020 project (seatech2020.eu). The selected modeling platform is utilized for the life cycle assessment of three potential fuels of diesel, methanol, and liquefied natural gas (LNG). Different fuel production pathways and powertrain dual-fuel technologies have been taken into account as the main variables, while the subsidiary factors such as transportation parameters (fuel economy and Avg. speed) are included in the calculations. The economic aspect and emission reduction trade-off for various scenarios are conducted to introduce the optimal solution based on the stakeholder interest in the shipping industry. The study also considers the fuel transport to the respective ports for a selected vessel from diverse fuel export locations and travelled routes according to datasets available for the same project. The results provide a guideline to the shipping industry on selecting possible conventional/renewable fuel resources to use in marine engines with emission content during each adopted pathway, where the respective subsequent expenditure per 1 MJ of each fuel sample as the functional unit has been evaluated.
{"title":"Life Cycle Assessment of Different Marine Fuel Types and Powertrain Configurations for Financial and Environmental Impact Assessment in Shipping","authors":"H. Taghavifar, L. Perera","doi":"10.1115/omae2022-78774","DOIUrl":"https://doi.org/10.1115/omae2022-78774","url":null,"abstract":"\u0000 The fuel type selection according to optimal pathway from extraction of a raw material (feedstock) to its processing to transportation and finally its use in marine engines (well to wheel) based on the cost and emission criteria is the main motivation factor to conduct the current investigation. The undertaken procedure has been customized based on the available data (ship/bunker route and mileage, the ship powertrain system, etc.) of the shipping industry under the SeaTech H2020 project (seatech2020.eu). The selected modeling platform is utilized for the life cycle assessment of three potential fuels of diesel, methanol, and liquefied natural gas (LNG). Different fuel production pathways and powertrain dual-fuel technologies have been taken into account as the main variables, while the subsidiary factors such as transportation parameters (fuel economy and Avg. speed) are included in the calculations. The economic aspect and emission reduction trade-off for various scenarios are conducted to introduce the optimal solution based on the stakeholder interest in the shipping industry. The study also considers the fuel transport to the respective ports for a selected vessel from diverse fuel export locations and travelled routes according to datasets available for the same project. The results provide a guideline to the shipping industry on selecting possible conventional/renewable fuel resources to use in marine engines with emission content during each adopted pathway, where the respective subsequent expenditure per 1 MJ of each fuel sample as the functional unit has been evaluated.","PeriodicalId":408227,"journal":{"name":"Volume 5A: Ocean Engineering","volume":"97 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122781881","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
L. Perera, K. Belibassakis, E. Filippas, M. Premasiri
Ship owners should comply with the forthcoming IMO legislations that mandates a reduction of ship emissions of at least 40% by 2030 compared with the 2008 baseline. However, it is unlikely that the shipping industry will be able to achieve its 2030 and 2050 emission reduction targets relying only on existing vessel technologies. Hence, the required green ship technologies that relate to industrial digitalization and AI applications should be utilized onboard vessels to achieve these emission reduction targets. This study proposes to analyze a hybrid engine-propeller combinator diagram from both theoretical calculations, i.e. from the vessel hull design, as well as data driven calculations, i.e. from ship performance and navigation data sets, to compare their performance in a single model framework. That would consist of various machine learning applications to create AI. It is expected that such combinations will support to understand the variations among system-model uncertainties in vessels and ship systems as a system of systems and that can also support industrial digitalization in shipping. Furthermore, the hybrid engine-propeller combinator diagram can be utilized to establish the basis for advanced data analytics that will be used to identify optimal vessel navigation and ship system operational conditions.
{"title":"Advanced Data Analytics Based Hybrid Engine-Propeller Combinator Diagram for Green Ship Operations","authors":"L. Perera, K. Belibassakis, E. Filippas, M. Premasiri","doi":"10.1115/omae2022-79490","DOIUrl":"https://doi.org/10.1115/omae2022-79490","url":null,"abstract":"\u0000 Ship owners should comply with the forthcoming IMO legislations that mandates a reduction of ship emissions of at least 40% by 2030 compared with the 2008 baseline. However, it is unlikely that the shipping industry will be able to achieve its 2030 and 2050 emission reduction targets relying only on existing vessel technologies. Hence, the required green ship technologies that relate to industrial digitalization and AI applications should be utilized onboard vessels to achieve these emission reduction targets. This study proposes to analyze a hybrid engine-propeller combinator diagram from both theoretical calculations, i.e. from the vessel hull design, as well as data driven calculations, i.e. from ship performance and navigation data sets, to compare their performance in a single model framework. That would consist of various machine learning applications to create AI. It is expected that such combinations will support to understand the variations among system-model uncertainties in vessels and ship systems as a system of systems and that can also support industrial digitalization in shipping. Furthermore, the hybrid engine-propeller combinator diagram can be utilized to establish the basis for advanced data analytics that will be used to identify optimal vessel navigation and ship system operational conditions.","PeriodicalId":408227,"journal":{"name":"Volume 5A: Ocean Engineering","volume":"191 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132156481","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
“Waiting on weather” is a costly restraint on offshore vessel operability. Vessel operating windows are determined based on the relationships between the weather and vessel movement, and uncertainties in these predictions may result in vessel operations being ceased prematurely. To improve the efficiency of offshore operations, existing assumptions and calculations based on conventional response amplitude operators (RAOs) should be challenged and improved. A machine learning approach is presented as a means of enriching these conventional RAOs with data. The machine learning model uses sea state forecasts to predict vessel response spectra. The model is cleverly formulated to use any existing RAO as a fallback solution in the absence of sufficient data. When applied to a comprehensive real-world scenario, the model predominantly outperforms the “best” available existing RAO. The results can be used not only to improve wave-vessel response predictions, but also to improve our understanding of existing RAOs and their shortcomings. Ultimately, the work can contribute to reducing overconservatism in weather-based restrictions on offshore vessel operability.
{"title":"Machine Learning Based Prediction of Wave-Induced Vessel Response","authors":"A. Cetin, Vegard R. Solum, Cristina M. Evans","doi":"10.1115/omae2022-78261","DOIUrl":"https://doi.org/10.1115/omae2022-78261","url":null,"abstract":"\u0000 “Waiting on weather” is a costly restraint on offshore vessel operability. Vessel operating windows are determined based on the relationships between the weather and vessel movement, and uncertainties in these predictions may result in vessel operations being ceased prematurely. To improve the efficiency of offshore operations, existing assumptions and calculations based on conventional response amplitude operators (RAOs) should be challenged and improved. A machine learning approach is presented as a means of enriching these conventional RAOs with data.\u0000 The machine learning model uses sea state forecasts to predict vessel response spectra. The model is cleverly formulated to use any existing RAO as a fallback solution in the absence of sufficient data. When applied to a comprehensive real-world scenario, the model predominantly outperforms the “best” available existing RAO. The results can be used not only to improve wave-vessel response predictions, but also to improve our understanding of existing RAOs and their shortcomings. Ultimately, the work can contribute to reducing overconservatism in weather-based restrictions on offshore vessel operability.","PeriodicalId":408227,"journal":{"name":"Volume 5A: Ocean Engineering","volume":"216 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122387071","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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