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":null,"pages":null},"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":null,"pages":null},"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":null,"pages":null},"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":null,"pages":null},"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}
Maritime industries are constantly searching for a method to enhance ship efficiency, with increasing concern about the environmental impact and rising fuel prices. Marine biofouling is one of the factors that increase ship fuel consumption. However, removing the fouling of the ship requires effort for hull maintenance. Due to the trade-off between conducting maintenance and performance degradation, this study presents the development of a Model-Driven Decision Support System (MD-DSS) to predict the optimum time for underwater hull cleaning for biofouling management. Five stages (sub-models) are employed to develop a DSS, namely: ship resistance estimation, estimation of additional resistance due to biofouling, an iterative-based method for determining the best time to conduct the hull cleaning, and an analysis report. The implemented algorithm was validated by comparing its result with a manually scheduled maintenance date. The DSS is able to determine the best time (date) for maintenance in all given scenarios. By giving two scenarios of different maintenance costs and different fuel prices, the optimisation results produce the same number of maintenances. Within 60 months, four to five hull cleanings are required. It is also found that when the optimal number of maintenances is known, then increasing this number will not have any impact on reducing the hull cleaning costs because the reduction in fouling does not significantly reduce the costs incurred for maintenance. During several trials of the DSS, it is shown that the system can generate maintenance schedules for different time intervals of ship operation within an acceptable time. It takes approximately 52 minutes, 12 minutes, and 5 minutes consecutively to determine the maintenance schedules for ship operation intervals of 5 years, 2.5 years, and 1 year.
{"title":"DEVELOPMENT OF MODEL-DRIVEN DECISION SUPPORT SYSTEM TO SCHEDULE UNDERWATER HULL CLEANING","authors":"A. Dinariyana, Pande Pramudya Deva, I. Ariana","doi":"10.21278/brod73302","DOIUrl":"https://doi.org/10.21278/brod73302","url":null,"abstract":"Maritime industries are constantly searching for a method to enhance ship efficiency, with increasing concern about the environmental impact and rising fuel prices. Marine biofouling is one of the factors that increase ship fuel consumption. However, removing the fouling of the ship requires effort for hull maintenance. Due to the trade-off between conducting maintenance and performance degradation, this study presents the development of a Model-Driven Decision Support System (MD-DSS) to predict the optimum time for underwater hull cleaning for biofouling management. Five stages (sub-models) are employed to develop a DSS, namely: ship resistance estimation, estimation of additional resistance due to biofouling, an iterative-based method for determining the best time to conduct the hull cleaning, and an analysis report. The implemented algorithm was validated by comparing its result with a manually scheduled maintenance date. The DSS is able to determine the best time (date) for maintenance in all given scenarios. By giving two scenarios of different maintenance costs and different fuel prices, the optimisation results produce the same number of maintenances. Within 60 months, four to five hull cleanings are required. It is also found that when the optimal number of maintenances is known, then increasing this number will not have any impact on reducing the hull cleaning costs because the reduction in fouling does not significantly reduce the costs incurred for maintenance. During several trials of the DSS, it is shown that the system can generate maintenance schedules for different time intervals of ship operation within an acceptable time. It takes approximately 52 minutes, 12 minutes, and 5 minutes consecutively to determine the maintenance schedules for ship operation intervals of 5 years, 2.5 years, and 1 year.","PeriodicalId":55594,"journal":{"name":"Brodogradnja","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2022-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47165575","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":null,"pages":null},"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}
S. Samuel, O. Mursid, S. Yulianti, Kiryanto, Muhammad Iqbal
A planing hull is a high-speed craft with relatively complex hydrodynamic characteristics. An increase in speed can induce a significant change in trim angle with an increment in ship drag. One solution to reduce ship resistance is to use an interceptor. This research aimed to analyze the hydrodynamics of a planing hull vessel by applying an interceptor. The fundamental aspects reviewed included the analysis of drag, trim, heave, and lift force. The interceptor would be investigated on the basis of its integrated position at its height. This research also used the computational fluid dynamic (CFD) method in calm water conditions. All simulations were conducted with the same mesh structure, which allowed the performance evaluation of the interceptor in calculating turbulent air–water flow around the ship. Numerical calculations used the Reynolds-averaged Navier–Stokes (RANS) equation with the k–ε turbulence model to predict the turbulent flow. The vertical motion of the ship was modeled using dynamic fluid–body interaction (DFBI) in the fluid domain through an overset mesh technique. The numerical approach was compared with the experimental test results of Park et al. to ensure the accuracy of the test results. The interceptor was designed at the transition phase, which showed the highest trim angle followed by high drag. The interceptor would experience negative trim at high speeds; thus, it was not recommended. The research results indicated that the most effective use of the interceptor was at Froude number 0.87 close to the chine position with a height of 100%. This interceptor could reduce a maximum of 57% drag, 17% heave, 8.48% trim, and 0.12% lift force. The interceptor could increase excessive drag and trim at Froude numbers over 1.16. The interceptor proved to be remarkably useful in trim control and ship drag reduction, but selecting the wrong dimensions and positions of the interceptor could endanger the ship. This simulation was performed on Aragon-2; thus, the interceptor performance may possibly change if a different hull geometry is used.
{"title":"EVALUATION OF INTERCEPTOR DESIGN TO REDUCE DRAG ON PLANING HULL","authors":"S. Samuel, O. Mursid, S. Yulianti, Kiryanto, Muhammad Iqbal","doi":"10.21278/brod73306","DOIUrl":"https://doi.org/10.21278/brod73306","url":null,"abstract":"A planing hull is a high-speed craft with relatively complex hydrodynamic characteristics. An increase in speed can induce a significant change in trim angle with an increment in ship drag. One solution to reduce ship resistance is to use an interceptor. This research aimed to analyze the hydrodynamics of a planing hull vessel by applying an interceptor. The fundamental aspects reviewed included the analysis of drag, trim, heave, and lift force. The interceptor would be investigated on the basis of its integrated position at its height. This research also used the computational fluid dynamic (CFD) method in calm water conditions. All simulations were conducted with the same mesh structure, which allowed the performance evaluation of the interceptor in calculating turbulent air–water flow around the ship. Numerical calculations used the Reynolds-averaged Navier–Stokes (RANS) equation with the k–ε turbulence model to predict the turbulent flow. The vertical motion of the ship was modeled using dynamic fluid–body interaction (DFBI) in the fluid domain through an overset mesh technique. The numerical approach was compared with the experimental test results of Park et al. to ensure the accuracy of the test results. The interceptor was designed at the transition phase, which showed the highest trim angle followed by high drag. The interceptor would experience negative trim at high speeds; thus, it was not recommended. The research results indicated that the most effective use of the interceptor was at Froude number 0.87 close to the chine position with a height of 100%. This interceptor could reduce a maximum of 57% drag, 17% heave, 8.48% trim, and 0.12% lift force. The interceptor could increase excessive drag and trim at Froude numbers over 1.16. The interceptor proved to be remarkably useful in trim control and ship drag reduction, but selecting the wrong dimensions and positions of the interceptor could endanger the ship. This simulation was performed on Aragon-2; thus, the interceptor performance may possibly change if a different hull geometry is used.","PeriodicalId":55594,"journal":{"name":"Brodogradnja","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2022-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48219673","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}
R. Hantoro, E. Septyaningrum, Yusuf Rifqi Hudaya, I. Utama
Ocean waves are a renewable energy source with abundant reserves in Indonesia. With the vast waters of Indonesia, the development of a sea wave power plant needs to be developed. This research focuses on the development of easy-operated and maintained ocean wave converter–pendulum system (OWC – PS). The numerical simulation and experimental analysis were conducted to obtain the relation between the motion response of the pontoon array and its pendulum. The pontoon used is the trimaran type, which consists of a cylindrical pontoon as the main hull and two outriggers on its side. This study analyses the most stable array arrangement that produces maximum pitching motion and pendulum deviation. The simulation results show that the largest pitching value is in array 1, i.e., 27.91° for pontoon 1 and 38.92° for pontoon 2, which results in a maximum pendulum deviation of 100 ° for pendulums 1 and 56.2 ° for pendulum 2 over a wave period of 9 seconds. The backward motion of the pendulum in both array configurations tends to have a greater deviation than that of the forward motion. The pendulums of array 1 have different motion characteristics, represented by different deviation values in both pendulums. This phenomenon does not occur in array 2, since both pendulums in array 2 have the same deviation (with only a small discrepancy).
{"title":"STABILITY ANALYSIS FOR TRIMARAN PONTOON ARRAY IN WAVE ENERGY CONVERTER – PENDULUM SYSTEM (WEC - PS)","authors":"R. Hantoro, E. Septyaningrum, Yusuf Rifqi Hudaya, I. Utama","doi":"10.21278/brod73304","DOIUrl":"https://doi.org/10.21278/brod73304","url":null,"abstract":"Ocean waves are a renewable energy source with abundant reserves in Indonesia. With the vast waters of Indonesia, the development of a sea wave power plant needs to be developed. This research focuses on the development of easy-operated and maintained ocean wave converter–pendulum system (OWC – PS). The numerical simulation and experimental analysis were conducted to obtain the relation between the motion response of the pontoon array and its pendulum. The pontoon used is the trimaran type, which consists of a cylindrical pontoon as the main hull and two outriggers on its side. This study analyses the most stable array arrangement that produces maximum pitching motion and pendulum deviation. The simulation results show that the largest pitching value is in array 1, i.e., 27.91° for pontoon 1 and 38.92° for pontoon 2, which results in a maximum pendulum deviation of 100 ° for pendulums 1 and 56.2 ° for pendulum 2 over a wave period of 9 seconds. The backward motion of the pendulum in both array configurations tends to have a greater deviation than that of the forward motion. The pendulums of array 1 have different motion characteristics, represented by different deviation values in both pendulums. This phenomenon does not occur in array 2, since both pendulums in array 2 have the same deviation (with only a small discrepancy).","PeriodicalId":55594,"journal":{"name":"Brodogradnja","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2022-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42337361","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 emphasis of this paper is on challenges in simulation of cavitating flows, especially flows around propeller and rudder. First the sources of errors in predictions based on Computational Fluid Dynamics (CFD) are highlighted: the accuracy of geometry, grid quality and fineness, turbulence modeling and cavitation modeling. The interaction between errors from different sources is also discussed. The importance of turbulence in the flow upstream of propeller and the difficulty of accounting for it is described next. Special attention is paid to the prediction of tip-vortex cavitation and to scale effects. Results from simulations are compared to experimental data from SVA Potsdam, except for the full-scale analysis of flow around hull, propeller and rudder, for which no experimental data is available. It is concluded that cavitation can be predicted to a degree which makes simulation an indispensable tool for design and optimization of maritime vessels.
{"title":"PREDICTION OF CAVITATION ON SHIPS","authors":"M. Peric","doi":"10.21278/brod73303","DOIUrl":"https://doi.org/10.21278/brod73303","url":null,"abstract":"The emphasis of this paper is on challenges in simulation of cavitating flows, especially flows around propeller and rudder. First the sources of errors in predictions based on Computational Fluid Dynamics (CFD) are highlighted: the accuracy of geometry, grid quality and fineness, turbulence modeling and cavitation modeling. The interaction between errors from different sources is also discussed. The importance of turbulence in the flow upstream of propeller and the difficulty of accounting for it is described next. Special attention is paid to the prediction of tip-vortex cavitation and to scale effects. Results from simulations are compared to experimental data from SVA Potsdam, except for the full-scale analysis of flow around hull, propeller and rudder, for which no experimental data is available. It is concluded that cavitation can be predicted to a degree which makes simulation an indispensable tool for design and optimization of maritime vessels.","PeriodicalId":55594,"journal":{"name":"Brodogradnja","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2022-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49112269","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper presents an unmanned surface vehicle Tritor that was developed, constructed, and tested within an innovative, multi-purpose, multidisciplinary, low-budget and environmentally friendly solution. The idea behind this work was trying to invent a new concept of a miniature surface vehicle that will be unmanned, remotely controlled and autonomous, with electric propulsion, and with an innovative Three Slender Cylinders Hull (3SCH) form gaining advantages in comparison to existing surface vehicles. This initial work is focused on vehicle prototype design, propulsion system development and optimization, control design, and trials, while research related to advantages of the vehicle in terms of naval architecture criteria such as drag and power, stability, seakeeping, and maneuverability will be investigated in further work. In addition, the paper intends to contribute to a new trend in developing vehicles with electrical propulsion that could use renewable sources of energy such as wind and solar energy. The potential usage of the vehicle can be civilian or military, and further work will be focused on larger models, improved based on the experience got during the development of the vehicle. Tritor vehicle was successfully designed, constructed, and tested in real environmental conditions. The preliminary results show that the vehicle has required performances and potential for improvements in the future. The main scientific contribution of this work is advanced surface vehicle development with a focus on a new hull form and the integration of electric propulsion in it.
{"title":"UNMANNED SURFACE VEHICLE – TRITOR","authors":"Andrija Ljulj, V. Slapničar, Juraj Brigić","doi":"10.21278/brod73308","DOIUrl":"https://doi.org/10.21278/brod73308","url":null,"abstract":"This paper presents an unmanned surface vehicle Tritor that was developed, constructed, and tested within an innovative, multi-purpose, multidisciplinary, low-budget and environmentally friendly solution. The idea behind this work was trying to invent a new concept of a miniature surface vehicle that will be unmanned, remotely controlled and autonomous, with electric propulsion, and with an innovative Three Slender Cylinders Hull (3SCH) form gaining advantages in comparison to existing surface vehicles. This initial work is focused on vehicle prototype design, propulsion system development and optimization, control design, and trials, while research related to advantages of the vehicle in terms of naval architecture criteria such as drag and power, stability, seakeeping, and maneuverability will be investigated in further work. In addition, the paper intends to contribute to a new trend in developing vehicles with electrical propulsion that could use renewable sources of energy such as wind and solar energy. The potential usage of the vehicle can be civilian or military, and further work will be focused on larger models, improved based on the experience got during the development of the vehicle. Tritor vehicle was successfully designed, constructed, and tested in real environmental conditions. The preliminary results show that the vehicle has required performances and potential for improvements in the future. The main scientific contribution of this work is advanced surface vehicle development with a focus on a new hull form and the integration of electric propulsion in it.","PeriodicalId":55594,"journal":{"name":"Brodogradnja","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2022-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47250225","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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