During the design phase of an offshore unit, estimating the station-keeping capabilities of the dynamic positioning (DP) system is mandatory. This means, in conventional offshore applications, to determine the maximum sustainable wind speed as a function of the encounter heading, which the unit may counteract by employing the onboard actuators or mooring lines only. Besides the deterministic estimation of DP capability, it is possible to assess the operability of the DP system following a non-deterministic probabilistic process by employing the site-specific joint wind-wave distributions to model the environment. In such a case, the operability results from a Monte Carlo integration process. Here it is proposed to enhance the applicability of the probabilistic analysis of DP operability, investigating the application of a Quasi-Monte Carlo method. In this sense, the procedure uses quasi-random samplings following a Sobol sequence instead of employing random samples of the joint distributions. In this paper, the Quasi-Monte Carlo process is tested and compared on a reference ship, highlighting the improvements to the established probabilistic DP prediction concerning the number of calculations needed to estimate operability. The significant reduction of computational time makes the newly implemented method suitable for the early design stage applications.
{"title":"Probabilistic evaluation of dynamic positioning operability with a Quasi-Monte Carlo approach","authors":"Francesco Mauro","doi":"10.21278/brod75105","DOIUrl":"https://doi.org/10.21278/brod75105","url":null,"abstract":"During the design phase of an offshore unit, estimating the station-keeping capabilities of the dynamic positioning (DP) system is mandatory. This means, in conventional offshore applications, to determine the maximum sustainable wind speed as a function of the encounter heading, which the unit may counteract by employing the onboard actuators or mooring lines only. Besides the deterministic estimation of DP capability, it is possible to assess the operability of the DP system following a non-deterministic probabilistic process by employing the site-specific joint wind-wave distributions to model the environment. In such a case, the operability results from a Monte Carlo integration process. Here it is proposed to enhance the applicability of the probabilistic analysis of DP operability, investigating the application of a Quasi-Monte Carlo method. In this sense, the procedure uses quasi-random samplings following a Sobol sequence instead of employing random samples of the joint distributions. In this paper, the Quasi-Monte Carlo process is tested and compared on a reference ship, highlighting the improvements to the established probabilistic DP prediction concerning the number of calculations needed to estimate operability. The significant reduction of computational time makes the newly implemented method suitable for the early design stage applications.","PeriodicalId":55594,"journal":{"name":"Brodogradnja","volume":"55 46","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139125376","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}
With the frequent occurrence of ship explosion accidents at sea, the safety of ships and crews has attracted much attention. At present, the research on crew injury is relatively weak. Consequently, the current study constructs a numerical model of the ship structure-crew-blast flow field to investigate the discrepancies in injury response of crew members across different sitting postures. LS-DYNA software is used for simulation and direct analysis to evaluate the damage of crew members in different positions under 100 kg TNT equivalent and 2 m blast distance conditions, and the relationship between different explosive equivalents and crew damage is analyzed. The results demonstrate that for crew members situated in working compartment, the injuries incurred across different sitting postures also differed. The lower leg and foot sections were at greater injury risks, while the head area was associated with minimal damage risks. Altering upper body postures of the crew human body had only a very small impact on lower extremity injuries. Moreover, positive correlations were exhibited between explosive equivalents and crew injury values. The research findings may offer references for injury analysis and protective device design of naval personnel.
随着海上船舶爆炸事故的频繁发生，船舶和船员的安全问题备受关注。目前，对船员伤害的研究相对薄弱。因此，本研究构建了一个船舶结构-船员-爆炸流场的数值模型，以研究船员在不同坐姿下的伤害反应差异。采用 LS-DYNA 软件进行模拟和直接分析，评估了 100 kg TNT 当量和 2 m 爆炸距离条件下不同坐姿船员的损伤情况，并分析了不同爆炸当量与船员损伤之间的关系。结果表明，对于工作舱内的乘员，不同坐姿造成的伤害也不同。小腿和脚部受到伤害的风险更大，而头部受到伤害的风险最小。改变船员的上半身姿势对下肢受伤的影响很小。此外，爆炸当量与船员受伤值之间呈正相关。研究结果可为海军人员的伤害分析和防护装置设计提供参考。
{"title":"Analysis of damage to ship personnel in different seated postures by near-field underwater explosions","authors":"Kai Li","doi":"10.21278/brod75107","DOIUrl":"https://doi.org/10.21278/brod75107","url":null,"abstract":"With the frequent occurrence of ship explosion accidents at sea, the safety of ships and crews has attracted much attention. At present, the research on crew injury is relatively weak. Consequently, the current study constructs a numerical model of the ship structure-crew-blast flow field to investigate the discrepancies in injury response of crew members across different sitting postures. LS-DYNA software is used for simulation and direct analysis to evaluate the damage of crew members in different positions under 100 kg TNT equivalent and 2 m blast distance conditions, and the relationship between different explosive equivalents and crew damage is analyzed. The results demonstrate that for crew members situated in working compartment, the injuries incurred across different sitting postures also differed. The lower leg and foot sections were at greater injury risks, while the head area was associated with minimal damage risks. Altering upper body postures of the crew human body had only a very small impact on lower extremity injuries. Moreover, positive correlations were exhibited between explosive equivalents and crew injury values. The research findings may offer references for injury analysis and protective device design of naval personnel.","PeriodicalId":55594,"journal":{"name":"Brodogradnja","volume":"8 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139128099","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}
In this paper, the slamming loads and structural response of an aluminium flat stiffened-plate structure during calm water entry considering the hydroelasticity effects are studied by a partitioned CFD-FEM two-way coupled method. The target structure is simplified as one segment of an idealized ship grillage structure, comprising flat plate and stiffeners. The typical numerical results are analyzed such as vertical displacement, velocity, acceleration, impact loads, and structural stress of the flexible flat bottom grillage structure considering the hydroelasticity effect and air cushion effect in different free fall height conditions. Drop test results of the same structure and other existing numerical simulation data by both coupled and uncoupled solutions in the literature are used for comparison with the present numerical simulation results. This study provides a practical means to simulate the slamming behaviour and structural response of ship structures, which is useful for predicting ship hull stiffened panel loads and related structural design.
{"title":"CFD-FEM simulation of water entry of aluminium flat stiffened plate structure considering the effects of hydroelasticity","authors":"Jialong Jiao","doi":"10.21278/brod75108","DOIUrl":"https://doi.org/10.21278/brod75108","url":null,"abstract":"In this paper, the slamming loads and structural response of an aluminium flat stiffened-plate structure during calm water entry considering the hydroelasticity effects are studied by a partitioned CFD-FEM two-way coupled method. The target structure is simplified as one segment of an idealized ship grillage structure, comprising flat plate and stiffeners. The typical numerical results are analyzed such as vertical displacement, velocity, acceleration, impact loads, and structural stress of the flexible flat bottom grillage structure considering the hydroelasticity effect and air cushion effect in different free fall height conditions. Drop test results of the same structure and other existing numerical simulation data by both coupled and uncoupled solutions in the literature are used for comparison with the present numerical simulation results. This study provides a practical means to simulate the slamming behaviour and structural response of ship structures, which is useful for predicting ship hull stiffened panel loads and related structural design.","PeriodicalId":55594,"journal":{"name":"Brodogradnja","volume":"17 5","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139129587","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 general cargo ships (GCSs) hold certain advantages over more mainstream shipping services, GCSs have a considerable degree of importance in the shipping market. This paper focuses on the use of risk evaluation procedures to perform empirical analysis of the operational risk faced by GCS operators, which is a subject that has garnered relatively little academic attention. After identifying risk factors, four risk aspects and 16 operational risk factors are determined and used to construct an Analytic Hierarchy Process (AHP)-based risk matrix evaluation model. An expert questionnaire addressing both subjective and objective facets is then used to perform evaluation of the model, enabling conversion of the relative weights to risk scales. Lastly, the determination of each risk factor’s risk areas allows the proposal of risk management strategies. The results indicate that four of the risk factors are in the high risk area; these consisted of the loading stage factor “delays at port of loading,” the laden voyage stage factor “poor stowage and securing,” the laden voyage stage factor “perils of the sea,” and the discharging stage factor “delays at port of discharge.” This paper also proposes risk management strategies on the basis of the experts’ recommendations, and its findings can provide shipowners and charterers with a reference for the drafting of risk clauses when entering into a charter party.
{"title":"An evaluation of operational risks for general cargo ship operators","authors":"Ji-Feng Ding","doi":"10.21278/brod75101","DOIUrl":"https://doi.org/10.21278/brod75101","url":null,"abstract":"As general cargo ships (GCSs) hold certain advantages over more mainstream shipping services, GCSs have a considerable degree of importance in the shipping market. This paper focuses on the use of risk evaluation procedures to perform empirical analysis of the operational risk faced by GCS operators, which is a subject that has garnered relatively little academic attention. After identifying risk factors, four risk aspects and 16 operational risk factors are determined and used to construct an Analytic Hierarchy Process (AHP)-based risk matrix evaluation model. An expert questionnaire addressing both subjective and objective facets is then used to perform evaluation of the model, enabling conversion of the relative weights to risk scales. Lastly, the determination of each risk factor’s risk areas allows the proposal of risk management strategies. The results indicate that four of the risk factors are in the high risk area; these consisted of the loading stage factor “delays at port of loading,” the laden voyage stage factor “poor stowage and securing,” the laden voyage stage factor “perils of the sea,” and the discharging stage factor “delays at port of discharge.” This paper also proposes risk management strategies on the basis of the experts’ recommendations, and its findings can provide shipowners and charterers with a reference for the drafting of risk clauses when entering into a charter party.","PeriodicalId":55594,"journal":{"name":"Brodogradnja","volume":"31 23","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139130005","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 study proposes a robust optimization method for waterborne emergency resource allocation in inland waterways that addresses the uncertainties and mismatches between supply and demand. To accomplish this, we integrate the risk evaluation of maritime with a robust optimization model and employ the Entropy Weighted Method (EWM)-Technique for Order Preference by Similarity to Ideal Solution (TOPSIS)-Analytic Hierarchy Process (AHP) method to evaluate the risk of various areas. The approach enables exploration of the relationship between maritime risk and emergency resource allocation strategy. The robust optimization method is used to deal with uncertainty and derive the robust counterpart of the proposed model. We establish an emergency resource allocation model that considers both the economy and timeliness of emergency resource allocation. We construct an optimization model and transform it into an easily solvable robust counterpart model. The results demonstrate that the proposed method can adapt to real-world scenarios, and effectively optimize the configuration effect while improving rescue efficiency under reasonable resource allocation. Specifically, the proportion of rescue time saved ranges from 28.52% to 92.60%, and the proportion of total cost saved is 95.82%. Our approach has significant potential to provide a valuable reference for decision-making related to emergency resource allocation in maritime management.
{"title":"Robust optimization method of emergency resource allocation for risk management in inland waterways","authors":"Quandang Ma","doi":"10.21278/brod75103","DOIUrl":"https://doi.org/10.21278/brod75103","url":null,"abstract":"This study proposes a robust optimization method for waterborne emergency resource allocation in inland waterways that addresses the uncertainties and mismatches between supply and demand. To accomplish this, we integrate the risk evaluation of maritime with a robust optimization model and employ the Entropy Weighted Method (EWM)-Technique for Order Preference by Similarity to Ideal Solution (TOPSIS)-Analytic Hierarchy Process (AHP) method to evaluate the risk of various areas. The approach enables exploration of the relationship between maritime risk and emergency resource allocation strategy. The robust optimization method is used to deal with uncertainty and derive the robust counterpart of the proposed model. We establish an emergency resource allocation model that considers both the economy and timeliness of emergency resource allocation. We construct an optimization model and transform it into an easily solvable robust counterpart model. The results demonstrate that the proposed method can adapt to real-world scenarios, and effectively optimize the configuration effect while improving rescue efficiency under reasonable resource allocation. Specifically, the proportion of rescue time saved ranges from 28.52% to 92.60%, and the proportion of total cost saved is 95.82%. Our approach has significant potential to provide a valuable reference for decision-making related to emergency resource allocation in maritime management.","PeriodicalId":55594,"journal":{"name":"Brodogradnja","volume":"30 2","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139130012","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 novel modal analysis methodology, denoted as the physics informed sparsity-promoting dynamic mode decomposition (pi-SPDMD) model, was introduced for the reduction and reconstruction analysis of intricate propeller wake flows, aiming to provide insight into the inherent flow structures spanning diverse temporal and spatial scales. Large-Eddy Simulation (LES) was employed to numerically model the wake dynamics of a four-bladed propeller, providing a comprehensive resolution from the proximate to the distant wake regions. The findings indicate that the pi-SPDMD model enhances the efficiency of the sparse-promoting algorithm, producing modes that gravitate towards stability, and the resulting decomposition maintains commendable physical fidelity. Integrating the results from the LES solution and the modal decomposition of pi-SPDMD, the tip vortex exhibits a uniform topological configuration with notable coherence in the proximate domain. In this region, the large-scale vortex is the dominant feature of the propeller wake, and there is a marked intermittency in the turbulence. In the mid-field, the tip vortex system transitions into fine-scale vortices, rapidly diminishing in coherence due to the onset of elliptic instability and subsequent secondary vortex generation. As the tip vortex structures related to physical quantities become fully discretized, the small-scale turbulent patterns quickly intermingle, leading to a more homogeneous distribution in the distant wake.
为对复杂的螺旋桨尾流进行还原和重构分析，引入了一种新的模态分析方法，称为物理信息稀疏性促进动态模态分解（pi-SPDMD）模型，旨在深入了解跨越不同时空尺度的固有流动结构。研究采用大型埃迪模拟（LES）对四叶螺旋桨的尾流动力学进行数值建模，提供了从近尾流区域到远尾流区域的全面分辨率。研究结果表明，pi-SPDMD 模型提高了稀疏促进算法的效率，产生了趋于稳定的模式，由此产生的分解保持了值得称道的物理保真度。综合 LES 解算结果和 pi-SPDMD 的模态分解结果，尖端漩涡呈现出均匀的拓扑结构，在近域具有显著的一致性。在该区域，大尺度涡是螺旋桨尾流的主要特征，湍流具有明显的间歇性。在中场，尖端涡旋系统过渡到细尺度涡旋，由于椭圆不稳定性的出现和随后次级涡旋的产生，相干性迅速减弱。随着与物理量相关的尖端涡旋结构完全离散化，小尺度湍流模式迅速交融，导致远处尾流的分布更加均匀。
{"title":"On the propeller wake evolution using large eddy simulations and physics-informed space-time decomposition","authors":"Zhan Zhang","doi":"10.21278/brod75102","DOIUrl":"https://doi.org/10.21278/brod75102","url":null,"abstract":"A novel modal analysis methodology, denoted as the physics informed sparsity-promoting dynamic mode decomposition (pi-SPDMD) model, was introduced for the reduction and reconstruction analysis of intricate propeller wake flows, aiming to provide insight into the inherent flow structures spanning diverse temporal and spatial scales. Large-Eddy Simulation (LES) was employed to numerically model the wake dynamics of a four-bladed propeller, providing a comprehensive resolution from the proximate to the distant wake regions. The findings indicate that the pi-SPDMD model enhances the efficiency of the sparse-promoting algorithm, producing modes that gravitate towards stability, and the resulting decomposition maintains commendable physical fidelity. Integrating the results from the LES solution and the modal decomposition of pi-SPDMD, the tip vortex exhibits a uniform topological configuration with notable coherence in the proximate domain. In this region, the large-scale vortex is the dominant feature of the propeller wake, and there is a marked intermittency in the turbulence. In the mid-field, the tip vortex system transitions into fine-scale vortices, rapidly diminishing in coherence due to the onset of elliptic instability and subsequent secondary vortex generation. As the tip vortex structures related to physical quantities become fully discretized, the small-scale turbulent patterns quickly intermingle, leading to a more homogeneous distribution in the distant wake.","PeriodicalId":55594,"journal":{"name":"Brodogradnja","volume":"23 12","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139127185","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}
To investigate the flow field characteristics of full-scale ships advancing through confined waters, the international standard container ship (KRISO Container Ship) was considered as a research object in this study. Using the RANS equation, the volume of fluid method and the body force method were selected to investigate the hydrodynamic characteristics of a model-scale ship (the model-scale ratio λ=31.6) and a full-scale ship advancing through confined waters at low speed. A virtual disk was used in the full-scale model to determine the influence of the propeller on the ship’s flow field. First, the feasibility of the numerical calculations was verified. This proves the feasibility of the numerical and grid division methods. The self-propulsion point of the full-scale ship at Fr=0.108 is determined. The calculation cases of model-scale and full-scale ships (with or without virtual disks) at different water depths and distances between the ship and the shore were calculated, and the changes in the hull surface pressure, the flow field around the ship, and the wake fraction near the ship propeller disk in different calculation cases were determined and compared. The variations in the surge force, sway force, and yaw moment between the model- scale and full-scale ships were generally consistent. In very shallow water (H/T=1.3), the non-dimensional force and moment coefficients for model-scale ships increase more rapidly with decreasing distance from shore, suggesting that using model-scale ships to investigate the wall effect in very shallow water will result in predictions that are biased towards safety. By comparing full-scale ships with and without propellers, it was discovered that the surge force, sway force, and yaw moment were marginally greater in the propeller-equipped ship due to the suction effect, and the accompanying flow before and after the propeller was slightly smaller, with less asymmetry.
{"title":"Influence of scale effect on flow field offset for ships in confined waters","authors":"ZhongXin Ma","doi":"10.21278/brod75106","DOIUrl":"https://doi.org/10.21278/brod75106","url":null,"abstract":"To investigate the flow field characteristics of full-scale ships advancing through confined waters, the international standard container ship (KRISO Container Ship) was considered as a research object in this study. Using the RANS equation, the volume of fluid method and the body force method were selected to investigate the hydrodynamic characteristics of a model-scale ship (the model-scale ratio λ=31.6) and a full-scale ship advancing through confined waters at low speed. A virtual disk was used in the full-scale model to determine the influence of the propeller on the ship’s flow field. First, the feasibility of the numerical calculations was verified. This proves the feasibility of the numerical and grid division methods. The self-propulsion point of the full-scale ship at Fr=0.108 is determined. The calculation cases of model-scale and full-scale ships (with or without virtual disks) at different water depths and distances between the ship and the shore were calculated, and the changes in the hull surface pressure, the flow field around the ship, and the wake fraction near the ship propeller disk in different calculation cases were determined and compared. The variations in the surge force, sway force, and yaw moment between the model- scale and full-scale ships were generally consistent. In very shallow water (H/T=1.3), the non-dimensional force and moment coefficients for model-scale ships increase more rapidly with decreasing distance from shore, suggesting that using model-scale ships to investigate the wall effect in very shallow water will result in predictions that are biased towards safety. By comparing full-scale ships with and without propellers, it was discovered that the surge force, sway force, and yaw moment were marginally greater in the propeller-equipped ship due to the suction effect, and the accompanying flow before and after the propeller was slightly smaller, with less asymmetry.","PeriodicalId":55594,"journal":{"name":"Brodogradnja","volume":"48 18","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139126829","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 small modular autonomous underwater vehicle (AUV) offers several benefits including enhanced mobility, cost-effectiveness, compact and portable structure, and small size. This paper proposes a comprehensive design and implementation approach for a small modular AUV, named as ARMs1.0, utilizing cutting-edge 3D printing technology. The main cabin shell of the AUV features a modular design and is manufactured using 3D printing technology. The control module and sensing equipment are installed in a sealed compartment. To achieve forward, pitching, and yawing motions, the AUV is equipped with ducted propeller and four independent rudders. The modular approach in AUV design has been implemented, considering both the main cabin shell as well as the subsections and segments of the AUV. Additionally, a centralized control system architecture design is developed based on the specific tasks of the AUV. The composition and functions of key units are described in detail, and an autonomous depth-tracking control strategy is formulated. Based on the experimental results for AUV motion in horizontal and vertical planes, including autonomous depth tracking tests, the ARMs1.0 AUV demonstrates the capability to successfully perform required maneuvering tasks. The designed small modular AUV has achieved accurate depth tracking, precise heading following and exhibits excellent maneuverability.
{"title":"Small Modular AUV Based on 3D Printing Technology: Design, Implementation and Experimental Validation","authors":"Lichun Yang","doi":"10.21278/brod75104","DOIUrl":"https://doi.org/10.21278/brod75104","url":null,"abstract":"A small modular autonomous underwater vehicle (AUV) offers several benefits including enhanced mobility, cost-effectiveness, compact and portable structure, and small size. This paper proposes a comprehensive design and implementation approach for a small modular AUV, named as ARMs1.0, utilizing cutting-edge 3D printing technology. The main cabin shell of the AUV features a modular design and is manufactured using 3D printing technology. The control module and sensing equipment are installed in a sealed compartment. To achieve forward, pitching, and yawing motions, the AUV is equipped with ducted propeller and four independent rudders. The modular approach in AUV design has been implemented, considering both the main cabin shell as well as the subsections and segments of the AUV. Additionally, a centralized control system architecture design is developed based on the specific tasks of the AUV. The composition and functions of key units are described in detail, and an autonomous depth-tracking control strategy is formulated. Based on the experimental results for AUV motion in horizontal and vertical planes, including autonomous depth tracking tests, the ARMs1.0 AUV demonstrates the capability to successfully perform required maneuvering tasks. The designed small modular AUV has achieved accurate depth tracking, precise heading following and exhibits excellent maneuverability.","PeriodicalId":55594,"journal":{"name":"Brodogradnja","volume":"63 29","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139127214","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. Trimulyono, M. L. Hakim, Chairizal Ardhan, Syaiful Tambah Putra Ahmad, T. Tuswan, A. W. B. Santosa
Along with developing high-speed craft technology, the planing hull is growing with modifications for better performance. One such technology is stepped hull, both single and double. Planing hull with steps allows the boat to run at a relatively low drag-lift ratio with lower frictional resistance due to reduced wetted area. In this study, the hull was modified with variations in the position of the double steps, which aimed to determine the effect of the first and second step positions on the total resistance, dynamic trim, and dynamic sinkage generated by computational fluid dynamics (CFD). Based on the analysis results, variations in the position of the stepped can change the hull performance. Shortening the distance between the two steps and moving both rearwards toward the transom can lower the total resistance. The dynamic trim and dynamic sinkage decreased as the position of the two steps was shifted further forward. An equation created in a non-dimensional form relates the positions of two steps to the desired results of total resistance, dynamic trim, and dynamic sinkage, namely: {(x1-x2)/L + (x1x2)/(LB)} × Fr∇, where x1 is distance the first step from transom, x2 is the distance of the second step, L is the length of the boat, B is the beam of the boat, and Fr∇ is the volume Froude number.
{"title":"Analysis of the double steps position effect on planing hull performances","authors":"A. Trimulyono, M. L. Hakim, Chairizal Ardhan, Syaiful Tambah Putra Ahmad, T. Tuswan, A. W. B. Santosa","doi":"10.21278/brod74403","DOIUrl":"https://doi.org/10.21278/brod74403","url":null,"abstract":"Along with developing high-speed craft technology, the planing hull is growing with modifications for better performance. One such technology is stepped hull, both single and double. Planing hull with steps allows the boat to run at a relatively low drag-lift ratio with lower frictional resistance due to reduced wetted area. In this study, the hull was modified with variations in the position of the double steps, which aimed to determine the effect of the first and second step positions on the total resistance, dynamic trim, and dynamic sinkage generated by computational fluid dynamics (CFD). Based on the analysis results, variations in the position of the stepped can change the hull performance. Shortening the distance between the two steps and moving both rearwards toward the transom can lower the total resistance. The dynamic trim and dynamic sinkage decreased as the position of the two steps was shifted further forward. An equation created in a non-dimensional form relates the positions of two steps to the desired results of total resistance, dynamic trim, and dynamic sinkage, namely: {(x1-x2)/L + (x1x2)/(LB)} × Fr∇, where x1 is distance the first step from transom, x2 is the distance of the second step, L is the length of the boat, B is the beam of the boat, and Fr∇ is the volume Froude number.","PeriodicalId":55594,"journal":{"name":"Brodogradnja","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43710193","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}
Tsunami wave characteristics are greatly influenced by the initial water level when they attack structures. In this study, experimental and numerical investigations were conducted to investigated the relationship between tsunami wave characteristics and initial water levels. Results showed that, the wave height, wave velocity, and Froude number increase with the increase of tsunami wave intensity; the time history of water levels were influenced by the different initial water level conditions; the analytical solution proposed by Chanson (2005) may be extended to wet-bed conditions (for initial water level < 0.36 tsunami bore height in our experimental set-up). Due to the limitations of experimental ranges in the laboratory, the validated numerical model can provide more results for wider experimental ranges for tsunami bore investigations. It was observed from numerical results that, tsunami bore height increases with the increase of reservoir water level; tsunami bore velocity decreases with the increased initial water level on the bed; as the initial water level on the bed gradually increases, the mean tsunami bore Froude number shows a downward trend.
{"title":"Study on the relationship between tsunami waves in dam break state and initial water levels","authors":"Xiaohe Lai, Xin Deng, Cheng Chen, Chen Peng, Zixuan Li, Haoyan Chen","doi":"10.21278/brod74405","DOIUrl":"https://doi.org/10.21278/brod74405","url":null,"abstract":"Tsunami wave characteristics are greatly influenced by the initial water level when they attack structures. In this study, experimental and numerical investigations were conducted to investigated the relationship between tsunami wave characteristics and initial water levels. Results showed that, the wave height, wave velocity, and Froude number increase with the increase of tsunami wave intensity; the time history of water levels were influenced by the different initial water level conditions; the analytical solution proposed by Chanson (2005) may be extended to wet-bed conditions (for initial water level < 0.36 tsunami bore height in our experimental set-up). Due to the limitations of experimental ranges in the laboratory, the validated numerical model can provide more results for wider experimental ranges for tsunami bore investigations. It was observed from numerical results that, tsunami bore height increases with the increase of reservoir water level; tsunami bore velocity decreases with the increased initial water level on the bed; as the initial water level on the bed gradually increases, the mean tsunami bore Froude number shows a downward trend.","PeriodicalId":55594,"journal":{"name":"Brodogradnja","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42753237","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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