Installation of jacket platforms requires simultaneous and combined operations of multiple assets. Once the whole process has to be planned, it is necessary to predict in a fast and reliable way the possible weather limitations that may occur during the operations. The paper will present the major challenges of this unusual and innovative Dynamic Positioning analysis which has been carried out for Ana Jacket installation. The obtained results show that the Dynamic Positioning system of the core vessel in intact configuration is capable to hold the position for the investigated vessels' arrangements and design operative weather conditions. Lifting, upending and installation of Ana Jacket were carried out successfully in 2021.
{"title":"DP CHALLENGES IN ANA PLATFORM JACKET INSTALLATION","authors":"K. Ardavanis, R. Nabergoj, F. Mauro","doi":"10.21278/brod73401","DOIUrl":"https://doi.org/10.21278/brod73401","url":null,"abstract":"Installation of jacket platforms requires simultaneous and combined operations of multiple assets. Once the whole process has to be planned, it is necessary to predict in a fast and reliable way the possible weather limitations that may occur during the operations. The paper will present the major challenges of this unusual and innovative Dynamic Positioning analysis which has been carried out for Ana Jacket installation. The obtained results show that the Dynamic Positioning system of the core vessel in intact configuration is capable to hold the position for the investigated vessels' arrangements and design operative weather conditions. Lifting, upending and installation of Ana Jacket were carried out successfully in 2021.","PeriodicalId":55594,"journal":{"name":"Brodogradnja","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2022-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49422509","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
As it is known, to provide fire protection for any type of surface vessel, external fire-fighting (EFF) systems have been commonly used for decades as well as in coastal regions. These types of systems exist on several types of vessels such as fire-fighting ships, tugboats, supply vessels and naval vessels. Flow conditioners can be used in the EFF systems to provide better performance by regulating the flow inside the fi-fi monitor. In the present study, a fire-fighting (fi-fi) monitor was designed and different flow conditioners were implemented into the fi-fi monitor. A unique flow conditioner was designed in addition to the recommended ones by ISO 5167-3 in order to improve the performance of the flow conditioner in terms of head ratio and flow rate. A commercial computational fluid dynamics (CFD) solver was used to investigate the performance of the different flow conditioners. Before comparing the numerical results of different flow conditioners, the numerical model was validated with the experimental data and verified with appropriate methods. The results showed that the unique flow conditioner successfully regulates the streamlines and it has better performance than the recommended ones by ISO 5167-3 in terms of flow rate and head ratio. As the last part of the study, the effect of unique flow conditioner length was investigated and the best length was determined.
{"title":"AN EXTENSIVE INVESTIGATION OF FLOW CONDITIONERS INSIDE A FI-FI MONITOR","authors":"Ahmet Bilir, Ali Doğrul, N. Vardar","doi":"10.21278/brod73408","DOIUrl":"https://doi.org/10.21278/brod73408","url":null,"abstract":"As it is known, to provide fire protection for any type of surface vessel, external fire-fighting (EFF) systems have been commonly used for decades as well as in coastal regions. These types of systems exist on several types of vessels such as fire-fighting ships, tugboats, supply vessels and naval vessels. Flow conditioners can be used in the EFF systems to provide better performance by regulating the flow inside the fi-fi monitor. In the present study, a fire-fighting (fi-fi) monitor was designed and different flow conditioners were implemented into the fi-fi monitor. A unique flow conditioner was designed in addition to the recommended ones by ISO 5167-3 in order to improve the performance of the flow conditioner in terms of head ratio and flow rate. A commercial computational fluid dynamics (CFD) solver was used to investigate the performance of the different flow conditioners. Before comparing the numerical results of different flow conditioners, the numerical model was validated with the experimental data and verified with appropriate methods. The results showed that the unique flow conditioner successfully regulates the streamlines and it has better performance than the recommended ones by ISO 5167-3 in terms of flow rate and head ratio. As the last part of the study, the effect of unique flow conditioner length was investigated and the best length was determined.","PeriodicalId":55594,"journal":{"name":"Brodogradnja","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2022-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46136460","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Cheng Chen, Chen Peng, Hong Xiao, Tingyu Wang, Minjian Wei
As new energy technologies boom in recent years, marine renewable energy, especially wave power is one potential trend. However, few relevant studies focus on extreme sea conditions. In this paper, a numerical model of typhoon waves in the Taiwan Strait is established based on the third-generation ocean wave model SWAN and then calculated by the wave energy empirical equation. Typhoon No. 200808 Fung-wong, strong typhoon No. 200815 Jangmi and strong typhoon No. 201808 Maria are used for verification and analysis. Finally, the results show that most concentrated wave energy values are more than 300 kW/m for typhoon and more than 900 kW/m for strong typhoons, over 60 times and 180 times the annual average (5 kW/m) in the Chinese sea area, respectively. In terms of other locations, corresponding values are more than 50 kW/m and over 100 kW/m. Therefore, typhoons’ wave energy is certainly a huge asset if fully utilized.
{"title":"NUMERICAL DISTRIBUTION SIMULATION OF TYPHOONS’ WAVE ENERGY IN THE TAIWAN STRAIT AND ITS ADJACENT WATERS","authors":"Cheng Chen, Chen Peng, Hong Xiao, Tingyu Wang, Minjian Wei","doi":"10.21278/brod73403","DOIUrl":"https://doi.org/10.21278/brod73403","url":null,"abstract":"As new energy technologies boom in recent years, marine renewable energy, especially wave power is one potential trend. However, few relevant studies focus on extreme sea conditions. In this paper, a numerical model of typhoon waves in the Taiwan Strait is established based on the third-generation ocean wave model SWAN and then calculated by the wave energy empirical equation. Typhoon No. 200808 Fung-wong, strong typhoon No. 200815 Jangmi and strong typhoon No. 201808 Maria are used for verification and analysis. Finally, the results show that most concentrated wave energy values are more than 300 kW/m for typhoon and more than 900 kW/m for strong typhoons, over 60 times and 180 times the annual average (5 kW/m) in the Chinese sea area, respectively. In terms of other locations, corresponding values are more than 50 kW/m and over 100 kW/m. Therefore, typhoons’ wave energy is certainly a huge asset if fully utilized.","PeriodicalId":55594,"journal":{"name":"Brodogradnja","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2022-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43242164","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Inland waterways are presented both as a need and an opportunity for developing an intermodal transport system to boost Colombian economic growth. Riverine transportation as part of an intermodal system represents conveying a significant amount of cargo at a low cost and therefore reducing greenhouse gas emissions. To competitively include this cargo transportation alternative in an intermodal context, the development of effective container vessels is required. Most of the Colombian rivers present sedimentary, high flow, and low depth nature. Then, the design of riverine cargo vessels capable of navigating in shallow waters with less brake power requirements is needed. A synthesis model: an automatic and integrated design procedure, has been programmed to generate and evaluate feasible vessel dimensions at a conceptual design stage. Through systematic variations of the main dimensions, this procedure allows evaluating a design space in which the most effective concept-vessel solution is selected. At the end of this procedure, the main characteristics for container vessels in the Magdalena River at a conceptual design stage, are defined. Validation of the synthesis model with a riverine logistic support ship is provided.
{"title":"SYNTHESIS MODEL FOR THE CONCEPTUAL DESIGN OF INLAND CARGO VESSELS TO OPERATE ON THE MAGDALENA RIVER","authors":"David Ricardo Alvarado, L. Paternina, E. Paipa","doi":"10.21278/brod73402","DOIUrl":"https://doi.org/10.21278/brod73402","url":null,"abstract":"Inland waterways are presented both as a need and an opportunity for developing an intermodal transport system to boost Colombian economic growth. Riverine transportation as part of an intermodal system represents conveying a significant amount of cargo at a low cost and therefore reducing greenhouse gas emissions. To competitively include this cargo transportation alternative in an intermodal context, the development of effective container vessels is required. Most of the Colombian rivers present sedimentary, high flow, and low depth nature. Then, the design of riverine cargo vessels capable of navigating in shallow waters with less brake power requirements is needed. A synthesis model: an automatic and integrated design procedure, has been programmed to generate and evaluate feasible vessel dimensions at a conceptual design stage. Through systematic variations of the main dimensions, this procedure allows evaluating a design space in which the most effective concept-vessel solution is selected. At the end of this procedure, the main characteristics for container vessels in the Magdalena River at a conceptual design stage, are defined. Validation of the synthesis model with a riverine logistic support ship is provided.","PeriodicalId":55594,"journal":{"name":"Brodogradnja","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2022-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42242820","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Z. Saydam, Gözde Nur Küçüksu, M. Insel, Serhan Gökçay
RANS-CFD is a well-established tool with widespread use in maritime industry and research. Valuable information might be extracted from the results of such simulations in terms of ship resistance and flow field variables. With recent advancements in computational power, it became possible to investigate the performance of ships in self-propulsion conditions with RANS method. This paper presents the results of a study in which self-propulsion analyses of a small size product/oil tanker has been carried out at ship scale. The methodology proposed in this study makes use of open water propeller performance predictions, resistance analyses at model scale and self-propulsion computations at ship scale for a minimum of 2 different propeller loadings to obtain the self-propulsion point and respective performance parameters. In order to speed up the time-consuming self-propulsion computations, these cases have been solved with a single-phase approach. Resistance predictions have been compared with experimental findings. Uncertainty associated with prediction of resistance and thrust has been quantified. Additionally, sea trials have been conducted on the subject vessel and its two sisters and measured delivered power data have been used for evaluating the capability of the numerical method in self-propulsion predictions. Comparison of results indicate that the proposed self-propulsion computation methodology with RANS CFD at ship scale is capable of predicting delivered power with sufficient accuracy at an acceptable computational cost.
{"title":"UNCERTAINTY QUANTIFICATION OF SELF-PROPULSION ANALYSES WITH RANS-CFD AND COMPARISON WITH FULL-SCALE SHIP TRIALS","authors":"A. Z. Saydam, Gözde Nur Küçüksu, M. Insel, Serhan Gökçay","doi":"10.21278/brod73406","DOIUrl":"https://doi.org/10.21278/brod73406","url":null,"abstract":"RANS-CFD is a well-established tool with widespread use in maritime industry and research. Valuable information might be extracted from the results of such simulations in terms of ship resistance and flow field variables. With recent advancements in computational power, it became possible to investigate the performance of ships in self-propulsion conditions with RANS method. This paper presents the results of a study in which self-propulsion analyses of a small size product/oil tanker has been carried out at ship scale. The methodology proposed in this study makes use of open water propeller performance predictions, resistance analyses at model scale and self-propulsion computations at ship scale for a minimum of 2 different propeller loadings to obtain the self-propulsion point and respective performance parameters. In order to speed up the time-consuming self-propulsion computations, these cases have been solved with a single-phase approach. Resistance predictions have been compared with experimental findings. Uncertainty associated with prediction of resistance and thrust has been quantified. Additionally, sea trials have been conducted on the subject vessel and its two sisters and measured delivered power data have been used for evaluating the capability of the numerical method in self-propulsion predictions. Comparison of results indicate that the proposed self-propulsion computation methodology with RANS CFD at ship scale is capable of predicting delivered power with sufficient accuracy at an acceptable computational cost.","PeriodicalId":55594,"journal":{"name":"Brodogradnja","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2022-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45561970","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
K. Li, Z. Zhao, S. Chang, J. Bao, Zhijiang Yuan, Xiaogang Jiang
The focus of this paper is to investigate the damage characteristics and protective structure design of pontoons as an important barrier for the protection of ports. Two types of protective measures of pontoons are investigated：filling tanks with water and installing springs in tanks. In this paper, the damage characteristics of two types of pontoon side structures under the action of near-field explosion loads are simulated by using LS-DYNA explicit dynamic analysis software and the ALE algorithm. According to the numerical experiment results for filling different volumes of water in the side tanks, the volume of water for the minimum deformation of the shell plate is 100%, and for the first longitudinal bulkhead, it is 30-40%. Moreover, by applying weights to their deformations based on the actual explosion-proof performance requirements of the shell plate and the first longitudinal bulkhead, the pontoon side structure with the best explosion-proof performance can be obtained. The plastic deformation of the pontoon structure equipped with different types of springs is an order of magnitude smaller than that of the ordinary structure and of the pontoon structure filled with a water medium in the positive tanks. The explosive shock wave energy absorbed by the pontoon is effectively reduced by the addition of water or springs to the protective tanks. The minimum energy absorbed by the pontoon structure with water added in the protective tanks is 18.31% of the energy absorbed by the ordinary structure, and the corresponding volume ratio of water added in the protective tanks is 100%. The pontoon structure with springs in the side protection tanks absorbs only 7.2% of the energy absorbed by the ordinary structure. Both new side protection structures have demonstrated excellent explosion-proof performance.
{"title":"RESEARCH ON DAMAGE CHARACTERISTICS AND PROTECTIVE STRUCTURE DESIGN OF STEEL PONTOONS UNDER NEAR-FIELD EXPLOSION LOAD","authors":"K. Li, Z. Zhao, S. Chang, J. Bao, Zhijiang Yuan, Xiaogang Jiang","doi":"10.21278/brod73404","DOIUrl":"https://doi.org/10.21278/brod73404","url":null,"abstract":"The focus of this paper is to investigate the damage characteristics and protective structure design of pontoons as an important barrier for the protection of ports. Two types of protective measures of pontoons are investigated：filling tanks with water and installing springs in tanks. In this paper, the damage characteristics of two types of pontoon side structures under the action of near-field explosion loads are simulated by using LS-DYNA explicit dynamic analysis software and the ALE algorithm. According to the numerical experiment results for filling different volumes of water in the side tanks, the volume of water for the minimum deformation of the shell plate is 100%, and for the first longitudinal bulkhead, it is 30-40%. Moreover, by applying weights to their deformations based on the actual explosion-proof performance requirements of the shell plate and the first longitudinal bulkhead, the pontoon side structure with the best explosion-proof performance can be obtained. The plastic deformation of the pontoon structure equipped with different types of springs is an order of magnitude smaller than that of the ordinary structure and of the pontoon structure filled with a water medium in the positive tanks. The explosive shock wave energy absorbed by the pontoon is effectively reduced by the addition of water or springs to the protective tanks. The minimum energy absorbed by the pontoon structure with water added in the protective tanks is 18.31% of the energy absorbed by the ordinary structure, and the corresponding volume ratio of water added in the protective tanks is 100%. The pontoon structure with springs in the side protection tanks absorbs only 7.2% of the energy absorbed by the ordinary structure. Both new side protection structures have demonstrated excellent explosion-proof performance.","PeriodicalId":55594,"journal":{"name":"Brodogradnja","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2022-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48817932","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The safety of mooring systems and accessories is one of the most critical issues in the structural integrity of floating oil/gas and renewable offshore structures. Mooring chains and accessories operate under dynamic conditions in harsh marine environments. They are subject to severe wear and corrosion between their links due to relative movement from waves, wind, and ocean currents that disrupt structural integrity. To cope with this problem, the pack-aluminizing process was applied on the R4 grade offshore mooring chain steel for 2 h at 850 °C to improve corrosion and wear-corrosion (tribocorrosion) resistance in 3.5% NaCl. The tribocorrosion behaviour of untreated and aluminized samples was investigated by a tribo-electrochemical setup that simultaneously allows for collecting the wear and corrosion data. Potentiodynamic and potentiostatic corrosion and tribocorrosion tests were carried out to understand corrosion kinetics. Optical, SEM, XRD and EDS analyses were performed to characterize the aluminide layer and surface morphologies before and after tribocorrosion investigations. In polarization scans under corrosion and tribocorrosion conditions, the current showed a significant activation stretch of several orders of magnitude, with minor potential changes in the anodic region. Due to the galvanic effects of sliding under natural electrochemical conditions, the untreated R4 alloy exhibited cathodic properties in the wear track, while the aluminium coating was out of the wear track due to its oxide-forming ability. At the cathodic potential, two hard Al2O3 materials under pure mechanical effects and third bodies emerging from cracks on the coating surface increase the friction coefficient (COF), while the oxide product film, which has a lubricating ability and pits which reduces the contact area, caused a decrease in COF at the high anodic potential. The study revealed that while the aluminide layer improved the corrosion and tribological character of R4 alloy, material loss from wear track increased due to micro fractures and cracks in the coating layer during sliding tribocorrosion conditions.
{"title":"ENHANCEMENT OF MARINE CORROSION AND TRIBOCORROSION RESISTANCE OF OFFSHORE MOORING CHAIN STEEL BY ALUMINIZING PROCESS","authors":"S. Alkan","doi":"10.21278/brod73407","DOIUrl":"https://doi.org/10.21278/brod73407","url":null,"abstract":"The safety of mooring systems and accessories is one of the most critical issues in the structural integrity of floating oil/gas and renewable offshore structures. Mooring chains and accessories operate under dynamic conditions in harsh marine environments. They are subject to severe wear and corrosion between their links due to relative movement from waves, wind, and ocean currents that disrupt structural integrity. To cope with this problem, the pack-aluminizing process was applied on the R4 grade offshore mooring chain steel for 2 h at 850 °C to improve corrosion and wear-corrosion (tribocorrosion) resistance in 3.5% NaCl. The tribocorrosion behaviour of untreated and aluminized samples was investigated by a tribo-electrochemical setup that simultaneously allows for collecting the wear and corrosion data. Potentiodynamic and potentiostatic corrosion and tribocorrosion tests were carried out to understand corrosion kinetics. Optical, SEM, XRD and EDS analyses were performed to characterize the aluminide layer and surface morphologies before and after tribocorrosion investigations. In polarization scans under corrosion and tribocorrosion conditions, the current showed a significant activation stretch of several orders of magnitude, with minor potential changes in the anodic region. Due to the galvanic effects of sliding under natural electrochemical conditions, the untreated R4 alloy exhibited cathodic properties in the wear track, while the aluminium coating was out of the wear track due to its oxide-forming ability. At the cathodic potential, two hard Al2O3 materials under pure mechanical effects and third bodies emerging from cracks on the coating surface increase the friction coefficient (COF), while the oxide product film, which has a lubricating ability and pits which reduces the contact area, caused a decrease in COF at the high anodic potential. The study revealed that while the aluminide layer improved the corrosion and tribological character of R4 alloy, material loss from wear track increased due to micro fractures and cracks in the coating layer during sliding tribocorrosion conditions.","PeriodicalId":55594,"journal":{"name":"Brodogradnja","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2022-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48942629","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A numerical study is conducted to determine the hydrodynamic coupling characteristics of a contra-rotating azimuth propulsor (CRAP) in open-water conditions. The detached-eddy simulation (DES) method is utilized to run simulations. A grid verification is conducted and the numerical results are validated based on a puller-type podded propeller. The hydrodynamic forces (i.e., thrusts and torques) are in accordance with the experimental data. The validated numerical method is utilized for subsequent CRAP simulations. The hydrodynamic performance and hydrodynamic coupling characteristics of CRAP are quantitatively analyzed according to forward propeller (FP), rear propeller (RP), and pod unit (PU) indicators with special focus on the hydrodynamic forces and the corresponding unsteadiness. PU appears to have essentially the same effect on the hydrodynamic performance of FP and RP. RP has a weak effect on the hydrodynamic performance of FP, while FP intensely affects that of RP. In general, the CRAP unsteadiness is dominated by RP, especially under heavy loading conditions.
{"title":"INVESTIGATION ABOUT THE HYDRODYNAMIC COUPLING CHARACTERISTICS OF CONTRA-ROTATING AZIMUTH PROPULSOR","authors":"L. Hou, Qingcai Wang","doi":"10.21278/brod73405","DOIUrl":"https://doi.org/10.21278/brod73405","url":null,"abstract":"A numerical study is conducted to determine the hydrodynamic coupling characteristics of a contra-rotating azimuth propulsor (CRAP) in open-water conditions. The detached-eddy simulation (DES) method is utilized to run simulations. A grid verification is conducted and the numerical results are validated based on a puller-type podded propeller. The hydrodynamic forces (i.e., thrusts and torques) are in accordance with the experimental data. The validated numerical method is utilized for subsequent CRAP simulations. The hydrodynamic performance and hydrodynamic coupling characteristics of CRAP are quantitatively analyzed according to forward propeller (FP), rear propeller (RP), and pod unit (PU) indicators with special focus on the hydrodynamic forces and the corresponding unsteadiness. PU appears to have essentially the same effect on the hydrodynamic performance of FP and RP. RP has a weak effect on the hydrodynamic performance of FP, while FP intensely affects that of RP. In general, the CRAP unsteadiness is dominated by RP, especially under heavy loading conditions.","PeriodicalId":55594,"journal":{"name":"Brodogradnja","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2022-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47930404","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xingkun Zhou, Jinghao Chen, Zhengguang Ge, Tong Zhao, Wenhua Li
Deepwater subsea wellheads may be significantly threatened under extreme sea conditions and operations, especially when the seabed is composed of very soft clay properties. A numerical model of a deepwater wellhead system is established using the classic ocean pipe element and nonlinear spring element of ANSYS to examine the behaviors of subsea wellheads in diverse seabed soil. Nonlinear spring elements coded in the APDL language are used to model three types of seabed soils: very soft soil, soft soil, and firm soil. The dynamic and quasi-static behaviors of the wellhead system in the typical coupled and decoupled models of the drilling riser system are particularly investigated in depth. The effects of the nonlinear seabed soil properties on the detailed wellhead are realistically simulated using time domain and extremum analysis. The results show that the softer the seabed soil, the greater the displacement, rotation angle, curvature, and bending moment of deepwater subsea wellheads. When the seabed soil reaches a particular depth, the mechanical characteristics of the wellheads under the three types of seabed soil conditions are almost simultaneously close to zero. Overall, several conclusions reached in this study may provide some useful references for design and stability analysis.
{"title":"NUMERICAL INVESTIGATIONS ON THE EFFECTS OF SEABED SHALLOW SOILS ON A TYPICAL DEEPWATER SUBSEA WELLHEAD SYSTEM","authors":"Xingkun Zhou, Jinghao Chen, Zhengguang Ge, Tong Zhao, Wenhua Li","doi":"10.21278/brod73301","DOIUrl":"https://doi.org/10.21278/brod73301","url":null,"abstract":"Deepwater subsea wellheads may be significantly threatened under extreme sea conditions and operations, especially when the seabed is composed of very soft clay properties. A numerical model of a deepwater wellhead system is established using the classic ocean pipe element and nonlinear spring element of ANSYS to examine the behaviors of subsea wellheads in diverse seabed soil. Nonlinear spring elements coded in the APDL language are used to model three types of seabed soils: very soft soil, soft soil, and firm soil. The dynamic and quasi-static behaviors of the wellhead system in the typical coupled and decoupled models of the drilling riser system are particularly investigated in depth. The effects of the nonlinear seabed soil properties on the detailed wellhead are realistically simulated using time domain and extremum analysis. The results show that the softer the seabed soil, the greater the displacement, rotation angle, curvature, and bending moment of deepwater subsea wellheads. When the seabed soil reaches a particular depth, the mechanical characteristics of the wellheads under the three types of seabed soil conditions are almost simultaneously close to zero. Overall, several conclusions reached in this study may provide some useful references for design and stability analysis.","PeriodicalId":55594,"journal":{"name":"Brodogradnja","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2022-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43525163","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Small underwater vehicles have unique advantages in ocean exploration. The resistance and volume of a vehicle are key factors affecting its operation time underwater. This paper aims to develop an effective method to obtain the optimal hull shape of a small underwater vehicle using Kriging-based response surface method (RSM) and multi-objective optimization algorithm. Firstly, the hydrodynamic performance of a small underwater vehicle is numerically investigated using computational fluid dynamics (CFD) method and the value range of related design variables is determined. The mesh convergence is verified to ensure the accuracy of the calculation results. Then, by means of the Latin hypercube sampling (LHS) design of simulation, the Kriging-based RSM model is developed according to the relation between each design variable of the vehicle and the output parameters applied to the vehicle. Based on the Kriging-based RSM model, the optimal hull shape of the vehicle is determined by using Screening and MOGA. As results, the vehicle resistance reduces and volume increases obviously.
{"title":"HULL SHAPE OPTIMIZATION OF SMALL UNDERWATER VEHICLE BASED ON KRIGING-BASED RESPONSE SURFACE METHOD AND MULTI-OBJECTIVE OPTIMIZATION ALGORITHM","authors":"Shuping Hou, Zejiang Zhang, Hongtai Lian, X. Xing, Haixia Gong, Xiujun Xu","doi":"10.21278/brod73307","DOIUrl":"https://doi.org/10.21278/brod73307","url":null,"abstract":"Small underwater vehicles have unique advantages in ocean exploration. The resistance and volume of a vehicle are key factors affecting its operation time underwater. This paper aims to develop an effective method to obtain the optimal hull shape of a small underwater vehicle using Kriging-based response surface method (RSM) and multi-objective optimization algorithm. Firstly, the hydrodynamic performance of a small underwater vehicle is numerically investigated using computational fluid dynamics (CFD) method and the value range of related design variables is determined. The mesh convergence is verified to ensure the accuracy of the calculation results. Then, by means of the Latin hypercube sampling (LHS) design of simulation, the Kriging-based RSM model is developed according to the relation between each design variable of the vehicle and the output parameters applied to the vehicle. Based on the Kriging-based RSM model, the optimal hull shape of the vehicle is determined by using Screening and MOGA. As results, the vehicle resistance reduces and volume increases obviously.","PeriodicalId":55594,"journal":{"name":"Brodogradnja","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2022-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42640124","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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