Journal of Marine Science and Technology最新文献

{"title":"Performance enhancement of a vortex ring thruster by adopting the Coanda effect","authors":"Woochan Seok, Young Min Heo, Shin Hyung Rhee","doi":"10.1007/s00773-024-01014-2","DOIUrl":"https://doi.org/10.1007/s00773-024-01014-2","url":null,"abstract":"<p>A vortex ring thruster (VRT) is a propulsion device in which a piston pushes fluid and thrusts it in reaction. As the fluid inside a VRT is moving, the boundary layer near the wall at the edge of the exit surface of a VRT separates and rolls up into a vortex ring. In this paper, we performed performance analysis on a regular VRT and a VRT enhanced by the Coanda effect (hereafter referred to as a CoVoRT) on axisymmetric geometry. A CoVoRT consists of two jets: a primary jet and a Coanda jet. The primary jet has a relatively large volume flow rate compared to the Coanda jet, and the Coanda jet attracts the surrounding fluid by flowing along the curved surface at a relatively small flow rate. The present study evaluates the propulsion performance in two ways using SNUFOAM. This software was developed based on OpenFOAM, which is an open-source computational fluid dynamics (CFD) toolkit and specialized for naval hydrodynamics. The first one quantifies the propulsion performance by calculating the ratio of energy input and energy output generated by two jets during a stroke of the piston motion. The second one is to observe the evolution and pinch-off process of a vortex ring with formation time, which is a non-dimensional time scale. The comparison of propulsion performance was conducted with changes in the curvature of the Coanda jet, changes in the length of the Coanda jet exit, and changes in the Coanda jet velocity and piston stroke ratio. For quantitative evaluation of propulsion performance, the propulsion performance evaluation index (PPEI) was introduced. The results showed that the PPEI of a CoVoRT was improved by about 50% compared to that of a VRT, and it was confirmed that the dynamic characteristics of a CoVoRT’s vortex ring were superior to those of a VRT in terms of propulsion performance.</p>","PeriodicalId":16334,"journal":{"name":"Journal of Marine Science and Technology","volume":"93 1","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141509809","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}

{"title":"Multi-ship collision avoidance decision-making method under complex encounter situations","authors":"Bo Xiang, Baofeng Pan, Guibing Zhu","doi":"10.1007/s00773-024-01009-z","DOIUrl":"https://doi.org/10.1007/s00773-024-01009-z","url":null,"abstract":"<p>This work addresses the issue of multi-ship collision avoidance decision-making complex encounter situations, and proposes a novel velocity varying-steering collision avoidance method based on an improved particle swarm optimization (IPSO) algorithm. The proposed method establishes a limited range based on the International Regulations for Preventing Collisions at Sea (COLREGs) and creates a multi-objective model, in which the collision risk of ships, the energy loss caused by velocity varying and the voyage loss caused by steering are taken into account. To obtain an optimal solution of the multi-objective model, an IPSO is introduced to determine the feasible solution domain for ship collision avoidance decision making(CADM). The proposed CADM is validated by numerical simulations and navigation simulator. The results indicate that the recommended velocity and course can effectively remove the risk of collision between the ship and target ships.</p>","PeriodicalId":16334,"journal":{"name":"Journal of Marine Science and Technology","volume":"4 1","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141253099","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}

{"title":"On the hydrodynamic derivatives with respect to heading angle for ship maneuvering in a canal","authors":"H. Yasukawa, M. Sano","doi":"10.1007/s00773-024-01004-4","DOIUrl":"https://doi.org/10.1007/s00773-024-01004-4","url":null,"abstract":"<p>This study focused on the equation of motion, hydrodynamic derivatives, and course stability with respect to ship maneuvering in a canal. Based on the potential theory, a consistent linearized equation of motion was derived when a ship maneuvers near the center line of a canal with a symmetrical cross-section and uniform length. In the new equation of motion, hydrodynamic derivatives for the lateral force and yaw moment with respect to ship heading angle <span>(psi)</span> (<span>(Y_psi)</span>, <span>(N_psi)</span>) appear, which have not been considered in existing studies. <span>(Y_psi)</span> and <span>(N_psi)</span> are measured by captive tests using a container ship model in a canal model, and they are significant. Furthermore, the course stability criterion for ships in the canal was derived by considering the <span>(Y_psi)</span> and <span>(N_psi)</span>, and the course stability was investigated. As a result, we found that the effect of <span>(Y_psi)</span> and <span>(N_psi)</span> on course stability cannot be neglected when the water depth becomes shallower. In case of the studied container ship, the consideration of <span>(Y_psi)</span> and <span>(N_psi)</span> causes the ship to shift to the course stable direction.</p>","PeriodicalId":16334,"journal":{"name":"Journal of Marine Science and Technology","volume":"138 1","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141198215","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}

{"title":"Submarine depth and pitch control based on closed-loop gain shaping algorithm","authors":"Daocheng Ma, Xianku Zhang, Jiaming Fan","doi":"10.1007/s00773-024-01002-6","DOIUrl":"https://doi.org/10.1007/s00773-024-01002-6","url":null,"abstract":"<p>In order to design a controller to control the pitch and depth of the submarine, this paper designs a submarine bow and stern rudder controller based on Closed-loop Gain Shaping Algorithm (CGSA) and nonlinear feedback and modification. The controller design considers the decoupling of the strong coupling of the submarine vertical surface motion model, the effect of wave disturbance and the optimization of the controller output. To verify the effectiveness and superiority of the proposed method, this research compares it with the Independent channel analysis and design (ICAD) method and introduces an evaluation index system to quantify the improvement effect. From the controller design process, the parameters of the CGSA are simple to solve and the engineering meaning is clear. From the simulation results, this controller can reach the setting depth quickly during the depth-changing maneuver. In the depth-keeping navigation stage, the control effect of depth and pitch angle is improved under wave disturbance, and the control energy evaluation index of the bow and stern rudder are reduced by 94.00% and 77.16% respectively, which proves that the controller has robust performance and energy saving effect. A new and efficient control algorithm is proposed for submarine motion control, which reduces the control energy while ensuring the control effect.</p>","PeriodicalId":16334,"journal":{"name":"Journal of Marine Science and Technology","volume":"62 1","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141172965","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}

{"title":"Air-borne stereo observation of ocean wave height using two independent cameras from a single unmanned aerial vehicle","authors":"Naoki Sawada, Daisuke Inazu, Lianhui Wu, Tsuyoshi Ikeya, Akio Okayasu","doi":"10.1007/s00773-024-01005-3","DOIUrl":"https://doi.org/10.1007/s00773-024-01005-3","url":null,"abstract":"<p>This study exploits a convenient, stable, accurate estimation of the spatio-temporal distribution of ocean wave heights by stereo observation using a single unmanned aerial vehicle (UAV) with two independent optical cameras fixed to it. To accurately estimate the spatio-temporal distribution of water levels, the photographing rate of each camera is set to 240 frames per second (fps), and luminescence captured during flight is used to realize the time synchronization within ~ 4 ms between the cameras. Based on the setting of the UAV and the cameras, we carry out aerial stereo observation of the spatio-temporal distribution of nearshore water levels. The estimated water levels showed good agreement with ground truth observation. We examine the dependence of the estimation accuracy on the photographing time difference between the cameras. Simulations were conducted to increase the time difference by decreasing the photographing rate. The estimation based on low photographing rates (e.g., 60 and 30 fps) likely failed when breaking wave crests prevailed in the optical images. This indicates that strict time synchronization (e.g., ~ 4 ms) between the cameras is an important, necessary condition to accomplish accurate stereo observation of ocean waves including wave breaking.</p>","PeriodicalId":16334,"journal":{"name":"Journal of Marine Science and Technology","volume":"25 1","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141147118","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}

{"title":"Flow field measurements around a marine propeller tip and vortex identification procedures","authors":"Daijiro Arakawa, Yuki Sawada, Koichiro Shiraishi, Takashi Kanemaru, Jun Ando","doi":"10.1007/s00773-024-00997-2","DOIUrl":"https://doi.org/10.1007/s00773-024-00997-2","url":null,"abstract":"<p>Propeller cavitation is one of the main causes of pressure fluctuation and noise around marine propellers, and tip vortex cavitation is one of the main causes of high-frequency underwater radiated noise. To predict tip vortex cavitation, it is necessary to correctly describe the radius of the vortex core and the vortex circulation of the tip vortex. Therefore, in this study, non-cavitating flow field measurements around the tip of model propellers were made for the 0.75 m diameter working section of the large cavitation tunnel at the National Maritime Research Institute, Japan (NMRI) using 2D-PIV. Identification procedures were investigated to develop a tip vortex model. The vortex properties (radius of vortex core and vortex circulation) of the tip vortex were obtained by applying by a Rankine vortex model and a Burgers vortex model. The measured velocity and vorticity values around the tip vortex as identified by the Burgers vortex model were in better agreement than those given by the Rankine vortex model. The Burgers vortex model was suitable for obtaining vortex properties from the measured flow field around the tip vortex. The vortex properties obtained from the identification using the Burgers vortex model showed the Reynolds number demonstrated a greater effect on the radius of the vortex core and vortex circulation. The higher the Reynolds numbers, the smaller the radius of the vortex core and the smaller vortex circulation tends to be. It is also shown that this Reynolds number effect differs depending on the blade shape of the propellers.</p>","PeriodicalId":16334,"journal":{"name":"Journal of Marine Science and Technology","volume":"17 1","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140884210","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}

{"title":"A simulator-based approach for testing and assessing human supervised autonomous ship navigation","authors":"Andreas Brandsæter, Andreas Madsen","doi":"10.1007/s00773-024-00998-1","DOIUrl":"https://doi.org/10.1007/s00773-024-00998-1","url":null,"abstract":"<p>This paper proposes and demonstrates a simulator-based approach for testing and assessing human operators’ ability and performance in supervising autonomous ships. In the autonomy concept studied here, it is assumed that the autonomous navigation system is capable of detecting and notifying the human operator prior to entering a challenging situation. The system will attempt to resolve the situation with a proposed evasive maneuver, but the system may occasionally make errors or select sub-optimal solutions. When the human operator is notified about a challenging situation, the operator should closely assess the situation, and intervene if (and only if) necessary. The proposed approach allows us to test and quantify the human operators’ abilities and performances in supervising an autonomously navigated ship. The approach is demonstrated on 56 simulator experiments, involving seven different navigators that perform eight different traffic scenarios. The scenarios are all based on real traffic data collected from a Norwegian ferry-crossing. The demonstration shows that the candidates are successful in supervising the autonomous ship in low-complexity traffic scenarios where it is easy for the operator to interpret the system’s decisions. The operators’ ability to intervene when and only when needed does, however, decline in more complex scenarios, and their performance is highly dependent on the traffic scenario and vary significantly between the candidates.</p>","PeriodicalId":16334,"journal":{"name":"Journal of Marine Science and Technology","volume":"150 1","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140840895","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}

{"title":"Study of effect of rotational axis configurations on the slosh dynamics of the ship-mounted tank under different combinations of rotational excitations","authors":"Khawaja Muhammad Abdullah, Muhammad Abdul Basit, Ajmal Shah","doi":"10.1007/s00773-024-00990-9","DOIUrl":"https://doi.org/10.1007/s00773-024-00990-9","url":null,"abstract":"<p>In maritime transportation systems, the stability and structural integrity of ship-mounted tanks subjected to sloshing phenomenon are critical due to economic considerations and to ensure ecological safety. During the voyage, the ships are subjected to external excitations, which induce sloshing in fluid in partially filled tanks mounted on the ship’s deck. This article investigates the effect of rotational axis configurations on the slosh dynamics of a 24,000 TEU water tank mounted on an Ever-Ace container ship. Sloshing phenomena caused by different combinations of piecewise sinusoidal rotational excitations have been compared. The fluid domain was simulated using ANSYS Fluent, coupled with transient structural analysis in ANSYS Mechanical, to analyze the structural integrity of the container. The fluid pressure loads were imported on the tank structure using a one-way FSI approach. The numerical results have been validated with the experimental data available in the literature. It has been found that the effects of viscous sub-layer are insignificant on the slosh dynamics of the tank. Moreover, the transient response of the air–water interface, impact pressure, and wall moment have been presented. Wave fluctuation is observed to be small when the axis of rotation is perpendicular to the free surface. Maximum impact pressure of 7 kPa has been observed for combination of roll and pitch motions. The range of amplitude of moment is maximum for combination of roll and pitch motions that varies from − 95.6 to 92.3 kN m. Furthermore, the frequency of the moment differed from the excitation frequency depending on the configuration of the rotational axis.</p>","PeriodicalId":16334,"journal":{"name":"Journal of Marine Science and Technology","volume":"51 1","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140006213","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}

{"title":"Basic design optimization of power and desalinated water for hybrid cycle ocean thermal energy conversion system integrated with desalination plant","authors":"Ahmad Aiman Azmi, Takeshi Yasunaga, Kevin Fontaine, Takafumi Morisaki, Tsutomu Nakaoka, Sathiabama T. Thirugnana, Abu Bakar Jaafar, Yasuyuki Ikegami","doi":"10.1007/s00773-024-00988-3","DOIUrl":"https://doi.org/10.1007/s00773-024-00988-3","url":null,"abstract":"<p>Ocean thermal energy conversion (OTEC) is a heat engine application that utilizes the Rankine cycle to extract energy from the thermal gradient between surface seawater and deep seawater. Hybrid cycle OTEC (H-OTEC) is a combination of an open cycle desalination system and a closed-cycle power generation system that leverages the features of both cycles. Unlike other desalination technologies that require extensive energy to operate, H-OTEC relies entirely on renewable energy. In addition, a desalination plant can be coupled with the H-OTEC system (H-OTEC + D) to improve its performance. Conventionally, the total heat transfer area of heat exchangers per net power is used as an objective function to achieve optimal performance with the lowest capital expenditure cost. The proposed objective function, unlike the conventional one, considers both power and water. In this study, the optimization of H-OTEC + D and H-OTEC is carried out by minimizing the proposed objective function, considering several independent variables. The performance of both systems is evaluated in terms of the objective function, power consumption, seawater flow rates, and desalination ratio. The findings also indicate the effectiveness of the proposed objective function over the conventional one as an effective tool for maximizing power and desalinated water generation.</p>","PeriodicalId":16334,"journal":{"name":"Journal of Marine Science and Technology","volume":"51 1","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139752270","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}

{"title":"An innovative EFD using FBG pressure sensors for ship seakeeping","authors":"Kantaro Suzuki, Hidetsugu Iwashita, Masashi Kashiwagi, Masahito Wakahara, Takahito Iida, Munehiko Minoura","doi":"10.1007/s00773-024-00986-5","DOIUrl":"https://doi.org/10.1007/s00773-024-00986-5","url":null,"abstract":"<p>This paper examines the acquisition of the measurement data of the spatial distribution of unsteady pressure on a ship advancing in waves. The purpose of the study is to investigate the reliability of the pressure data obtained by the unprecedented experiment and to provide experimental data of unsteady pressure which can be used for validation of arbitrary computation methods. The optical fiber sensing technology, so-called FBG (fiber Bragg gratings) sensing, is employed as the pressure sensors. In the experiment, 379 FBG pressure sensors (version 7; the latest version) in total are attached to the port side surface of ship model and also ordinary strain-type pressure sensors are embedded in the starboard side for validating reliability of FBG pressure sensors by comparing both results. In addition to the pressure distribution, measurement is made for unsteady hydrodynamic forces such as added mass, damping coefficients, and wave exciting forces, and also for ship motions and added resistance. Most of the measurement is repeated at least five times for each condition, and results of measured pressures are evaluated with mean value and standard deviation. Regarding the added resistance, the distribution for estimating added resistance is also extracted from obtained pressure distribution and its pressure contour is illustrated to show visually which hull region affects the added resistance significantly. Validation of the measured pressure with FBG pressure sensors is carried out also by integrating measured pressures over the ship model surface and comparing it with forces directly measured with load cells. The measured pressure distribution is compared with typical calculation results with the Rankine panel method in frequency domain to demonstrate usefulness of the spatial pressure data for validating the calculation method. Through these studies, it is confirmed that the measured unsteady pressures with FBG pressure sensors are accurate enough and valuable as the validation data for any calculation method.</p>","PeriodicalId":16334,"journal":{"name":"Journal of Marine Science and Technology","volume":"18 1","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139688574","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}