During the early design stage, it is essential to produce quick and reliable results. Regarding the calculation of forces acting on a rudder in the propeller slipstream, potential flow solvers are often used for this purpose due to their low computational effort. The drawback of these solvers is that viscous effects as drag or flow separation cannot be calculated. To overcome this drawback, the coupling of an inviscid three dimensional boundary element method with a viscous two dimensional boundary layer method is presented. The inflow from the propeller and the propeller rudder interaction is calculated using a lifting line approach. The inviscid calculation of the rudder forces is done with a boundary element method and the viscous rudder forces are calculated with the boundary layer method. Two different approaches are presented for the coupling. The results calculated with the implemented methods are compared to reverse open water model tests.
{"title":"Coupling of a Boundary Element Method With a Boundary Layer Method for Accurate Rudder Force Calculation Within the Early Design Stage","authors":"Björn Carstensen, S. Krüger","doi":"10.1115/omae2021-62363","DOIUrl":"https://doi.org/10.1115/omae2021-62363","url":null,"abstract":"\u0000 During the early design stage, it is essential to produce quick and reliable results. Regarding the calculation of forces acting on a rudder in the propeller slipstream, potential flow solvers are often used for this purpose due to their low computational effort. The drawback of these solvers is that viscous effects as drag or flow separation cannot be calculated. To overcome this drawback, the coupling of an inviscid three dimensional boundary element method with a viscous two dimensional boundary layer method is presented. The inflow from the propeller and the propeller rudder interaction is calculated using a lifting line approach. The inviscid calculation of the rudder forces is done with a boundary element method and the viscous rudder forces are calculated with the boundary layer method. Two different approaches are presented for the coupling. The results calculated with the implemented methods are compared to reverse open water model tests.","PeriodicalId":23784,"journal":{"name":"Volume 6: Ocean Engineering","volume":"26 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74058177","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}
Helene Lünser, M. Hartmann, N. Desmars, J. Behrendt, N. Hoffmann, Marco Klein
The accurate description of the complex genesis and evolution of ocean waves as well as the associated kinematics and dynamics is indispensable for the design of offshore structures and assessment of marine operations. In the majority of cases, the water wave problem is reduced to potential flow theory on a somehow simplified level. However, the non-linear terms in the surface boundary conditions and the fact that they must be fulfilled on the unknown water surface make the boundary value problem considerably complex. On the one hand, the use of complex methods for solving the boundary value problem may give, at the expense of computational time, a very accurate representation of reality. On the other hand, simplified methods are numerically efficient but may only provide sufficient accuracy for a limited range of applications. This paper investigates the influence of different characteristic sea state parameters on the accuracy of irregular wave field simulations (based on a JONSWAP spectrum) by applying the high-order spectral method. Hereby, the underlying Taylor series expansion is truncated at different orders so that numerical simulations of different complexity can be investigated. The wave steepness, spectral-peak enhancement factor as well as directional spreading are systematically varied and truncation at fourth order serves as reference. It is shown that, for specific parameters in terms of wave steepness, enhancement factor and simulation time, the boundary value problem can be significantly reduced while providing sufficient accuracy.
{"title":"Influence of Sea State Parameters on the Accuracy of Wave Simulations of Different Complexity","authors":"Helene Lünser, M. Hartmann, N. Desmars, J. Behrendt, N. Hoffmann, Marco Klein","doi":"10.1115/omae2021-62631","DOIUrl":"https://doi.org/10.1115/omae2021-62631","url":null,"abstract":"\u0000 The accurate description of the complex genesis and evolution of ocean waves as well as the associated kinematics and dynamics is indispensable for the design of offshore structures and assessment of marine operations. In the majority of cases, the water wave problem is reduced to potential flow theory on a somehow simplified level. However, the non-linear terms in the surface boundary conditions and the fact that they must be fulfilled on the unknown water surface make the boundary value problem considerably complex. On the one hand, the use of complex methods for solving the boundary value problem may give, at the expense of computational time, a very accurate representation of reality. On the other hand, simplified methods are numerically efficient but may only provide sufficient accuracy for a limited range of applications.\u0000 This paper investigates the influence of different characteristic sea state parameters on the accuracy of irregular wave field simulations (based on a JONSWAP spectrum) by applying the high-order spectral method. Hereby, the underlying Taylor series expansion is truncated at different orders so that numerical simulations of different complexity can be investigated. The wave steepness, spectral-peak enhancement factor as well as directional spreading are systematically varied and truncation at fourth order serves as reference.\u0000 It is shown that, for specific parameters in terms of wave steepness, enhancement factor and simulation time, the boundary value problem can be significantly reduced while providing sufficient accuracy.","PeriodicalId":23784,"journal":{"name":"Volume 6: Ocean Engineering","volume":"7 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78837155","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}
This paper presents the results of wind load computational fluid dynamics (CFD) calculations performed on the topside structures of a self-propelled wind turbine installation jack-up. The CFD calculations were performed for the jack-up topside structures with and without the deck load. An atmospheric boundary layer profile was applied for the model-scale calculations. The full range of heading angles was considered. The CFD results were validated through comparison with the wind tunnel tests which were carried out at the German-Dutch wind tunnels (DNW) in Marknesse, The Netherlands. Moreover, a comparison is presented between the applied boundary layer profiles throughout the CFD computational domain with those profiles measured in the wind tunnel. The CFD results were found to be in good agreement with the wind tunnel tests for the considered cases, verifying the feasibility of the CFD method as an important design tool for the prediction of wind loads during the design processes of these types of jack-ups.
{"title":"Predicting Wind Loads on the Topside of a Self-Propelled Wind Turbine Installation Jack-Up Using CFD","authors":"Z. Sulaiman","doi":"10.1115/omae2021-63445","DOIUrl":"https://doi.org/10.1115/omae2021-63445","url":null,"abstract":"\u0000 This paper presents the results of wind load computational fluid dynamics (CFD) calculations performed on the topside structures of a self-propelled wind turbine installation jack-up. The CFD calculations were performed for the jack-up topside structures with and without the deck load. An atmospheric boundary layer profile was applied for the model-scale calculations. The full range of heading angles was considered. The CFD results were validated through comparison with the wind tunnel tests which were carried out at the German-Dutch wind tunnels (DNW) in Marknesse, The Netherlands. Moreover, a comparison is presented between the applied boundary layer profiles throughout the CFD computational domain with those profiles measured in the wind tunnel. The CFD results were found to be in good agreement with the wind tunnel tests for the considered cases, verifying the feasibility of the CFD method as an important design tool for the prediction of wind loads during the design processes of these types of jack-ups.","PeriodicalId":23784,"journal":{"name":"Volume 6: Ocean Engineering","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87162112","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}
An integrated optimization model of EEDI and minimum propulsion power has been established in this paper. EEDI optimization needs to meet IMO requirements for minimum propulsion power. Installed power reduction is one of the most effective way to optimize EEDI, but it will make the installed power lower than IMO requirements. From the view of security, it is not allowed. In order to coordinate the contradiction between the reduction of EEDI and the minimum propulsion power of the ship, this paper is devoted to the development of an effective and efficient EEDI optimization method under the minimum propulsion power constraints of the ship. The evaluation method of the objective function EEDI is a digital pattern of hydrodynamics performance for tanker series developed by the China Ship Science Research Center. In order to illustrate the method, the VLCC is selected as the research object, and Non-dominated Sorting Genetic Algorithms II is selected to optimize the EEDI. The calculation results show that energy efficiency has been optimized about 4%, so the EEDI and minimum propulsion power integrated optimization model are reasonable and effective.
{"title":"Integrated Optimization of Principal Dimensions Based on EEDI and Minimum Propulsion Power","authors":"Yanxia Wang, Wenyu Sun, Qiang Zhao","doi":"10.1115/omae2021-63526","DOIUrl":"https://doi.org/10.1115/omae2021-63526","url":null,"abstract":"\u0000 An integrated optimization model of EEDI and minimum propulsion power has been established in this paper. EEDI optimization needs to meet IMO requirements for minimum propulsion power. Installed power reduction is one of the most effective way to optimize EEDI, but it will make the installed power lower than IMO requirements. From the view of security, it is not allowed. In order to coordinate the contradiction between the reduction of EEDI and the minimum propulsion power of the ship, this paper is devoted to the development of an effective and efficient EEDI optimization method under the minimum propulsion power constraints of the ship. The evaluation method of the objective function EEDI is a digital pattern of hydrodynamics performance for tanker series developed by the China Ship Science Research Center. In order to illustrate the method, the VLCC is selected as the research object, and Non-dominated Sorting Genetic Algorithms II is selected to optimize the EEDI. The calculation results show that energy efficiency has been optimized about 4%, so the EEDI and minimum propulsion power integrated optimization model are reasonable and effective.","PeriodicalId":23784,"journal":{"name":"Volume 6: Ocean Engineering","volume":"87 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81061802","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}
Despite of numbers of method to estimate and predict the nonlinear roll damping, it is the mode least understood and the most difficult to determine so far. Reviewing the existing methods reveals that the coupling effects of other modes on roll motion are ignored by assuming just one degree of freedom (1DOF) roll in experiments. The new concept of Most Often Instantaneous Rotation Center - MOIRC proposed by Fernandes and Asgari has brough other parameters, which can help us to improve the roll damping analysis by including the coupling (roll-sway) that results in asymmetric roll responses. This paper, by describing experiments, aims to confirm this roll-sway effect on roll damping coefficient by taking a well posed 3DOF, which allows to follow the instantaneous rotation centers - IRCs. The regular beam-waves experiments were conducted for different frequencies and wave amplitudes. A 3DOF (sway, heave and roll) system identification is used to extract roll damping from the model test. It is shown that the locus of the IRCs follows a straight line and it has a statistical behavior whose probability density function of IRCs with a Cauchy probability density function. For the first time this characteristic is provided experimentally, well matching with the analytical Cauchy distribution.
{"title":"Nonlinear Roll Damping With Coupling Effect in Regular Beam-Wave","authors":"Peyman Asgari, A. C. Fernandes","doi":"10.1115/omae2021-63596","DOIUrl":"https://doi.org/10.1115/omae2021-63596","url":null,"abstract":"\u0000 Despite of numbers of method to estimate and predict the nonlinear roll damping, it is the mode least understood and the most difficult to determine so far. Reviewing the existing methods reveals that the coupling effects of other modes on roll motion are ignored by assuming just one degree of freedom (1DOF) roll in experiments. The new concept of Most Often Instantaneous Rotation Center - MOIRC proposed by Fernandes and Asgari has brough other parameters, which can help us to improve the roll damping analysis by including the coupling (roll-sway) that results in asymmetric roll responses. This paper, by describing experiments, aims to confirm this roll-sway effect on roll damping coefficient by taking a well posed 3DOF, which allows to follow the instantaneous rotation centers - IRCs. The regular beam-waves experiments were conducted for different frequencies and wave amplitudes. A 3DOF (sway, heave and roll) system identification is used to extract roll damping from the model test. It is shown that the locus of the IRCs follows a straight line and it has a statistical behavior whose probability density function of IRCs with a Cauchy probability density function. For the first time this characteristic is provided experimentally, well matching with the analytical Cauchy distribution.","PeriodicalId":23784,"journal":{"name":"Volume 6: Ocean Engineering","volume":"45 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83611409","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}
We develop a fully-coupled time-domain hydro-elasticity model for the Submerged Floating Tunnel (SFT) based on the Discrete-Module-Beam (DMB) method. Frequency-domain simulation based on 3D potential theory results in multibody’s hydrodynamic coefficients and excitation forces for tunnel sections. Subsequently, we build the time-domain model with the multibody Cummins equation and external stiffness matrix from the Euler-Bernoulli and Saint-Venant torsion theories. We establish the mooring line model with rod theory and couple components with translational springs at their respective connection locations. We then compare the dynamic motions, wave forces, and mooring tensions between the present and Morison-equation-based elastic models under regular wave excitations at different submergence depths. The present model is especially important for the shallowly submerged tunnel in which the Morison model shows exaggerated motions, especially at high-frequency range.
{"title":"Coupled Time-Domain Hydro-Elastic Simulation for Submerged Floating Tunnel Under Wave Excitations","authors":"Chungkuk Jin, Sung-Jae Kim, Moo-Hyun Kim","doi":"10.1115/omae2021-62969","DOIUrl":"https://doi.org/10.1115/omae2021-62969","url":null,"abstract":"\u0000 We develop a fully-coupled time-domain hydro-elasticity model for the Submerged Floating Tunnel (SFT) based on the Discrete-Module-Beam (DMB) method. Frequency-domain simulation based on 3D potential theory results in multibody’s hydrodynamic coefficients and excitation forces for tunnel sections. Subsequently, we build the time-domain model with the multibody Cummins equation and external stiffness matrix from the Euler-Bernoulli and Saint-Venant torsion theories. We establish the mooring line model with rod theory and couple components with translational springs at their respective connection locations. We then compare the dynamic motions, wave forces, and mooring tensions between the present and Morison-equation-based elastic models under regular wave excitations at different submergence depths. The present model is especially important for the shallowly submerged tunnel in which the Morison model shows exaggerated motions, especially at high-frequency range.","PeriodicalId":23784,"journal":{"name":"Volume 6: Ocean Engineering","volume":"17 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90764028","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}
Air gap is pivotal to the hydrodynamic performance for the semi-submersible platform as a key characteristic for the strength assessment and safety evaluation. Considering the metocean conditions of the Norse Sea, the hydrodynamic performance of a semi-submersible platform has been analyzed. Based on the three-dimensional potential flow theory, and combined with the full QTF matrix and the second-order difference frequency loads, the nonlinear motion characteristics and the prediction for air gap have been simulated. The wave frequency motion response, the second-order nonlinear air gap response and nonlinear motion response of the platform have been analyzed. By comparing the simulation results, the air gap response of the platform considering the nonlinear motion is more intense than the results simulated by the first-order motion without considering the second-order difference frequency loads. Under the heavy metocean conditions, for the heave and pitch motion of the platform, the non-linear simulation values for some air gap points and areas are negative which means the wave slam has been occurred, but the calculation results of linear motion response indicate that the air gap above has not appeared the wave slamming areas. The simulation results present that the influence of the second-order wave loads is a critical part in the air gap prediction for the semi-submersible platform.
{"title":"A Numerical Simulation of Non-Linear Air-Gap for Deepwater Semi-Submersible Platform","authors":"Zhuang Kang, Yan-shuai Zhang, Haibo Sui, Rui Chang","doi":"10.1115/omae2021-62553","DOIUrl":"https://doi.org/10.1115/omae2021-62553","url":null,"abstract":"\u0000 Air gap is pivotal to the hydrodynamic performance for the semi-submersible platform as a key characteristic for the strength assessment and safety evaluation. Considering the metocean conditions of the Norse Sea, the hydrodynamic performance of a semi-submersible platform has been analyzed. Based on the three-dimensional potential flow theory, and combined with the full QTF matrix and the second-order difference frequency loads, the nonlinear motion characteristics and the prediction for air gap have been simulated. The wave frequency motion response, the second-order nonlinear air gap response and nonlinear motion response of the platform have been analyzed. By comparing the simulation results, the air gap response of the platform considering the nonlinear motion is more intense than the results simulated by the first-order motion without considering the second-order difference frequency loads. Under the heavy metocean conditions, for the heave and pitch motion of the platform, the non-linear simulation values for some air gap points and areas are negative which means the wave slam has been occurred, but the calculation results of linear motion response indicate that the air gap above has not appeared the wave slamming areas. The simulation results present that the influence of the second-order wave loads is a critical part in the air gap prediction for the semi-submersible platform.","PeriodicalId":23784,"journal":{"name":"Volume 6: Ocean Engineering","volume":"11 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90829430","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}
Cavitation is an undesirable phenomenon in the maritime industry as it causes damage to the propeller, degrading hydrodynamic performance and increasing the subsequent underwater radiated noise (URN). Therefore, mitigating cavitation on marine propellers is an important area of research in order to reduce carbon emissions emitted from the shipping industry and reduce the rate at which ocean ambient noise levels are increasing. The Humpback whale has provided inspiration to research in the fluid-structure interaction field due to the presence of leading-edge (LE) tubercles on the pectoral fins that allow it to perform acrobatic maneuvers to catch prey. This paper assesses the cavitation containment capability of the LE tubercles on a benchmark marine propeller in both heavy and light cavitating conditions using commercial code STAR-CCM+, unsteady incompressible Reynolds-averaged Navier Stokes (RANS) solver and the Schnerr-Sauer cavitation model to quantify the sheet cavitation present over a range of operating conditions. In summary, in heavy-cavitating conditions, a reduction in sheet cavitation with the inclusion of LE tubercles was observed to a maximum value of 2.75% in all operating conditions considered. A maximum improvement of 3.51% and 1.07% was predicted in propulsive thrust and hydrodynamic efficiency, respectively. In light cavitating conditions, although in some conditions a reduction in cavity volume was observed, this did not result in an improvement in hydrodynamic performance.
{"title":"The Influence of Leading-Edge Tubercles on the Sheet Cavitation Development of a Benchmark Marine Propeller","authors":"Callum Stark, Weichao Shi","doi":"10.1115/omae2021-62292","DOIUrl":"https://doi.org/10.1115/omae2021-62292","url":null,"abstract":"\u0000 Cavitation is an undesirable phenomenon in the maritime industry as it causes damage to the propeller, degrading hydrodynamic performance and increasing the subsequent underwater radiated noise (URN). Therefore, mitigating cavitation on marine propellers is an important area of research in order to reduce carbon emissions emitted from the shipping industry and reduce the rate at which ocean ambient noise levels are increasing. The Humpback whale has provided inspiration to research in the fluid-structure interaction field due to the presence of leading-edge (LE) tubercles on the pectoral fins that allow it to perform acrobatic maneuvers to catch prey. This paper assesses the cavitation containment capability of the LE tubercles on a benchmark marine propeller in both heavy and light cavitating conditions using commercial code STAR-CCM+, unsteady incompressible Reynolds-averaged Navier Stokes (RANS) solver and the Schnerr-Sauer cavitation model to quantify the sheet cavitation present over a range of operating conditions. In summary, in heavy-cavitating conditions, a reduction in sheet cavitation with the inclusion of LE tubercles was observed to a maximum value of 2.75% in all operating conditions considered. A maximum improvement of 3.51% and 1.07% was predicted in propulsive thrust and hydrodynamic efficiency, respectively. In light cavitating conditions, although in some conditions a reduction in cavity volume was observed, this did not result in an improvement in hydrodynamic performance.","PeriodicalId":23784,"journal":{"name":"Volume 6: Ocean Engineering","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90303743","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}
Humberto A. Uehara Sasaki, A. Ianagui, Pedro Cardozo de Mello, E. Tannuri
Retrieving certain hydrodynamics coefficients from a marine craft during a maneuver can be useful for various reasons, such as the validation of project specifications or the rapid verification of structural changes that could impact the vessel movement. Intended to estimate some of these parameters, the present work proposes a method purely based on traditional Extended Kalman Filter (EKF) focused for limited drift angles. Albeit not posing as a replacement to conventional estimations, such as from Computer Fluid Dynamics (CFD) — which solve equations in order of millions — and experimental tests — with its time-consuming preparation setups and post-analyses — the method can possibly present itself as a convenient and quicky technique to estimate the hydrodynamics coefficients in real time, as each iteration resorts only into a few dozen of equations. Preliminary results in the simulated environment called pyDyna — a python version of the Numerical Offshore Tank ship maneuvering simulator — indicate this procedure is faster along with an acceptable margin of accuracy, possibly pointing as a feature for future digital twin applications.
{"title":"Digital Twin of a Maneuvering Ship: Real-Time Estimation of Derivatives and Resistance Coefficient Based on Motion Sensor","authors":"Humberto A. Uehara Sasaki, A. Ianagui, Pedro Cardozo de Mello, E. Tannuri","doi":"10.1115/omae2021-62899","DOIUrl":"https://doi.org/10.1115/omae2021-62899","url":null,"abstract":"Retrieving certain hydrodynamics coefficients from a marine craft during a maneuver can be useful for various reasons, such as the validation of project specifications or the rapid verification of structural changes that could impact the vessel movement. Intended to estimate some of these parameters, the present work proposes a method purely based on traditional Extended Kalman Filter (EKF) focused for limited drift angles.\u0000 Albeit not posing as a replacement to conventional estimations, such as from Computer Fluid Dynamics (CFD) — which solve equations in order of millions — and experimental tests — with its time-consuming preparation setups and post-analyses — the method can possibly present itself as a convenient and quicky technique to estimate the hydrodynamics coefficients in real time, as each iteration resorts only into a few dozen of equations.\u0000 Preliminary results in the simulated environment called pyDyna — a python version of the Numerical Offshore Tank ship maneuvering simulator — indicate this procedure is faster along with an acceptable margin of accuracy, possibly pointing as a feature for future digital twin applications.","PeriodicalId":23784,"journal":{"name":"Volume 6: Ocean Engineering","volume":"42 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81618970","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}
Energy Efficiency Design Index (EEDI) entered Phase 2 in 2020. In this situation, ship performance in actual seas is more important than ever. As an energy saving bow shape in actual seas, the authors are developing a bow shape named “COVE (Concave shape optimized in waves)”. The aim of COVE is to improve performance in waves without deteriorating performance in a calm sea by transformation above the static swell up at the target speed. Since the bow shape is concave above the static swell up, COVE reduces waves reflected forward because the most concave line has a fine triangular shape instead of the blunt shape of the original. In this paper, COVE is applied to a Capesize bulk carrier, the JBC (Japan Bulk Carrier). The parameters of COVE are examined and the shape is optimized for the JBC. The effect of COVE is validated by tank tests in terms of wave lengths, wave angles, wave heights and ship speeds. The results clarified the fact that COVE reduces added resistance in waves by approximately 30 % in head waves compared with the original shape. Validity was verified by the radiating wave shape and the side wall wave form recorded by a video camera in the tests.
{"title":"Application of Energy Saving Bow Shape in Actual Seas to JBC","authors":"A. Sakurada, M. Tsujimoto, Saori Yokota","doi":"10.1115/omae2021-62246","DOIUrl":"https://doi.org/10.1115/omae2021-62246","url":null,"abstract":"\u0000 Energy Efficiency Design Index (EEDI) entered Phase 2 in 2020. In this situation, ship performance in actual seas is more important than ever.\u0000 As an energy saving bow shape in actual seas, the authors are developing a bow shape named “COVE (Concave shape optimized in waves)”. The aim of COVE is to improve performance in waves without deteriorating performance in a calm sea by transformation above the static swell up at the target speed. Since the bow shape is concave above the static swell up, COVE reduces waves reflected forward because the most concave line has a fine triangular shape instead of the blunt shape of the original.\u0000 In this paper, COVE is applied to a Capesize bulk carrier, the JBC (Japan Bulk Carrier). The parameters of COVE are examined and the shape is optimized for the JBC. The effect of COVE is validated by tank tests in terms of wave lengths, wave angles, wave heights and ship speeds.\u0000 The results clarified the fact that COVE reduces added resistance in waves by approximately 30 % in head waves compared with the original shape. Validity was verified by the radiating wave shape and the side wall wave form recorded by a video camera in the tests.","PeriodicalId":23784,"journal":{"name":"Volume 6: Ocean Engineering","volume":"11 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82525063","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：