Volume 5A: Ocean Engineering最新文献

{"title":"Design of the Propulsion System for the Autonomous XLUUV MUM","authors":"Martin Greve, M. Kurowski, Sebastian Ritz, M. Golz, Lakshmi Narasiman Vijayasarathi, Nursen Bayazit, Erik Rentzow","doi":"10.1115/omae2022-78583","DOIUrl":"https://doi.org/10.1115/omae2022-78583","url":null,"abstract":"\u0000 The paper reports on one aspect in the design of the extra-large unmanned underwater vehicle (XLUUV) MUM, referring to a large Modifiable Underwater Mothership. The vessel will be highly modular and has unique features, such as hydrogen fuel cell and lithium-ion batteries. Modules can be added and rearranged to fulfill different operations. The envisaged operation scenarios pose a challenge to the design of the propulsion and maneuvering system. Due to the limited power and energy storage, it must be efficient during submerged transit, capable of safe surfaced operation in public sea routes and of dynamic positioning. A design study is presented based on an initial design of two variants. The basic hull forms are compared in terms of required forces and moments for vessel motions. Simulations of hull forces are conducted using Reynolds-averaged Navier-Stokes (RANS) equations and vessel motions are determined with an actuator force model. Different arrangements of propulsors and thrusters are investigated and compared concerning their propulsion efficiency and their agility in translatory and rotary directions. The results are presented as tabulated data and in capability plots. A final design is presented and discussed and a conclusion is presented.","PeriodicalId":408227,"journal":{"name":"Volume 5A: Ocean Engineering","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126921094","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"On Some Nonlinear Wave Diffraction and Refraction Solutions in Shallow Waters","authors":"M. Hayatdavoodi, R. Ertekin","doi":"10.1115/omae2022-79413","DOIUrl":"https://doi.org/10.1115/omae2022-79413","url":null,"abstract":"\u0000 Diffraction and refraction of nonlinear shallow water waves due to uneven bathymetry is studied numerically in two and three dimensions. The numerical tank consists of a wavemaker at the upwave side of the domain, the submerged obstacles in the middle of the domain, and a numerical wave absorber on the downwave of the domain. The numerical wavemaker is capable of generating solitary and cnoidal waves as solutions of the Green-Naghdi (GN) equations. The nonlinear wave refraction and diffraction is studied by use of the Level I GN equations. The system of equations are solved numerically in time domain by use of a second-order finite difference approach, and in a boundary-fitted coordinate system. Various forms of three-dimensional bathymetry with large slopes, including flat and curved ramps from deep to shallow regions are considered. Results include solitary and cnoidal wave surface elevation and particle velocities and are compared with the existing solutions where possible. Overall very good agreement is observed. Discussion is provided on the nonlinearity and dispersion effects on the wave diffraction and refraction, as well as on the performance of the GN equations in solving these problems.","PeriodicalId":408227,"journal":{"name":"Volume 5A: Ocean Engineering","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128649120","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Stress Analysis for Three-Dimensional Structures Considering the Global Hydroelasticity by Beam Connected Discrete Modules Method","authors":"Shenmin Zhang, Shuai Li, Shixiao Fu, T. Moan, Z. Pan, Yuwang Xu, Bin Song","doi":"10.1115/omae2022-81325","DOIUrl":"https://doi.org/10.1115/omae2022-81325","url":null,"abstract":"\u0000 This paper proposes a stress analysis method for three-dimensional structures, with the consideration of the global hydroelasticity which is calculated through the beam connected discrete modules method. First, the continuous structure is discretized into rigid modules connected by elastically equivalent beams. The hydroelastic responses are solved by the coupling of the hydrodynamics of rigid modules and the structural stiffness of elastic beams. Then, according to six degrees of freedom motions of each module extracted from the hydroelasticity, the pressure distributions of rigid modules can be obtained based on the three-dimensional potential theory. Finally, the inertia force and the pressure distributions are statically loaded on three-dimensional finite element model. The process is applied to a barge under the regular wave. In rigid condition, the local stress using the proposed method is verified against the result from the Quasi-static method. Furthermore, the springing effect on the local stress is investigated. In the test model, the result shows that the springing effect induces an obvious difference.","PeriodicalId":408227,"journal":{"name":"Volume 5A: Ocean Engineering","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131469092","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"2D Discrete Module Beam (DMB) Method Formulation to Simulate Hydro-Elastic Structures With Two Horizontal Bending Axes","authors":"Farid P. Bakti, Chungkuk Jin, Moo-Hyun Kim","doi":"10.1115/omae2022-79802","DOIUrl":"https://doi.org/10.1115/omae2022-79802","url":null,"abstract":"\u0000 The 1D Discrete Module Beam (DMB) discretize hydro-elastic body into multiple independent rigid bodies (modules) connected by beam elements. The technique has proven accurate in representing structures with a large length-to-breadth ratio (L/B), such as floating bridge, barge, and ship structures. Only one horizontal bending axes are typically considered for such structures. Bending stiffness in the other horizontal axis is considered stiff and consequently treated as rigid. However, this assumption is not satisfied for structures with L/B closer to one. This study aims to extend the 1D DMB method into the 2D DMB method in the frequency domain to simulate hydro-elastic structures with two horizontal bending axes by arranging the beam elements into grid-like configurations in both horizontal axes (x and y). The method is then validated through comparisons with published experimental results and other numerical methods for various sea states. The method’s versatility is then demonstrated by incorporating linearized mooring stiffness in the frequency domain, which consequently changes the structures’ hydrodynamic response. It is found that for freely floating bodies, the centerline deformation of both the 1D and 2D DMB methods is the same. However, the 1D DMB method cannot properly capture the breadth-wise elastic-deformation in oblique waves and the moored case. In those cases, the 2D DMB formulation becomes particularly important. The presented 2D DMB method is projected to be a practical tool to simulate floating structures with unconventional configurations such as floating solar panels and other very large floating structures.","PeriodicalId":408227,"journal":{"name":"Volume 5A: Ocean Engineering","volume":"424 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131769392","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hydrodynamic Analysis in Marine Operations: A Preprocessing and Postprocessing Tool","authors":"J. Gullaksen","doi":"10.1115/omae2022-80153","DOIUrl":"https://doi.org/10.1115/omae2022-80153","url":null,"abstract":"\u0000 A pre- & post-processor for modelling and analysis of marine operations to support hydrodynamic subsea installation analysis is presented in this paper. The pre-processor is automating the input model for static analysis, that also includes preliminary estimates of load effects as basis for product configuration and input parameters to dynamic analysis models, including product specific capacities and limit state criteria directly related to installation operation. Subsea installation operations will normally be weather restricted operations demanding a thorough evaluation of relevant environmental conditions. Short-term wave conditions are described by a stochastic method using wave spectra, or the deterministic design wave method. Statistical distributions are used to describe long-term and extreme value conditions, or scatter diagrams for governing sea state parameters. Joint wave-current distributions of parameters and corresponding surfaces for given exceedance probability levels are considered. The analyses establish relevant installation parameters required in order to carry out the installation operations in a safe manner. Static analysis is also used for curve stability analysis, on-bottom stability analysis, recovery analysis, J-tube pull-in analysis, tie-in analysis and sensitivity analysis. The post-processor is used to display and review the static and dynamic analysis results, including compliance with the given limit state criteria under the relevant limiting weather conditions of each operation. This also includes easy comprehension of data supported by tools that provides the ability to easily view appropriate results quantities on all model objects. Important for a fast analysis turnaround is the ability to process the data and support the user in getting the necessary information to understand the model’s hydrodynamic behaviour.","PeriodicalId":408227,"journal":{"name":"Volume 5A: Ocean Engineering","volume":"208 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131401218","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Second Order Difference- and Sum-Frequency Wave Loads in the Open-Source Potential Flow Solver NEMOH","authors":"R. Kurnia, G. Ducrozet, J. Gilloteaux","doi":"10.1115/omae2022-79163","DOIUrl":"https://doi.org/10.1115/omae2022-79163","url":null,"abstract":"\u0000 Theoretical and numerical aspects of the open-source potential flow boundary element solver, NEMOH, for the first order hydrodynamic coefficients computations in the frequency domain are described in [Babarit, A. and Delhommeau, G., 2015]. [Philippe, M. et al., 2015] described the implementation and verifications of the second order difference-frequency quadratic transfer functions (QTFs) in the NEMOH code. In the latter paper, the QTFs are verified for standard cases, a bottom-mounted cylinder and a hemisphere. The present study reports the implementation and verification of the complete QTFs, for difference- and sum-frequency loads. The QTFs are composed of quadratic and potential parts. The quadratic part depending on the first order hydrodynamic quantities, is implemented using the near-field approach. The potential part, which depends on the second order potential, is solved using the indirect method. Verification is achieved by comparing the NEMOH result with a commercial software HYDROSTAR for a hemisphere and the OC5-DeepCwind semisubmersible.","PeriodicalId":408227,"journal":{"name":"Volume 5A: Ocean Engineering","volume":"681 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122976867","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Probabilistic Design of Thin-Walled Cylindrical Structures for Application In Large Cargo Submarines","authors":"Philip Lundberg Jamissen, Y. Xing, Yucong Ma","doi":"10.1115/omae2022-79485","DOIUrl":"https://doi.org/10.1115/omae2022-79485","url":null,"abstract":"\u0000 Collapse failure is the dominating failure mode of submarine pressure hulls due to the large hydrostatic pressure, which brings about a low collapse pressure capacity unless thick plates with closely spaced stiffeners are used. However, because cargo submarines require a high payload capacity to be economically attractive, an optimal design with low structural weight is vitally important. This makes thin-walled structures with a high strength-over-weight ratio favourable. Therefore, one crucial challenge relates to the research of large underwater cargo submarine concepts is to propose a cost-effective design for the collapse of the submarine pressure hulls. From experience, the collapse pressure capacity of thin-walled structures is susceptible to the geometric imperfections generated during manufacturing. For a safe design, a common practice used by the design-by-rule approach is introducing a very conservative safety factor. However, such an approach is not structurally efficient. This paper proposes a probabilistic design approach for cylindrical thin-walled structures for application in cargo submarine hulls. The initial imperfections are represented by the Fourier series. Stochastic realisations of the imperfections are made using the Monte Carlo method, and the corresponding collapse pressures are calculated using finite element analysis. The collapse pressures are then collected to plot the cumulative distribution function (CDF). Finally, the collapse pressure capacity can be defined from the CDF based on the desired failure probability. The results show that axial buckling of the thin-walled cylinder is sensitive to the initial imperfection and the distribution of critical buckling force follows Gumbel distribution. In contrast, SST structures subjected to external pressure load are not sensitive to initial imperfections. Gumbel distribution would overpredict the buckling pressure in this case. Also, it is shown that the collapse pressure capacities calculated using probabilistic design are significantly higher than the design-by-rule method.","PeriodicalId":408227,"journal":{"name":"Volume 5A: Ocean Engineering","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132241610","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"On the Calibration of Metocean Time Series Using Machine Learning","authors":"F. Enet, Olga Podrażka, L. Renac","doi":"10.1115/omae2022-80274","DOIUrl":"https://doi.org/10.1115/omae2022-80274","url":null,"abstract":"\u0000 Nowadays, numerical model data is one of the primary inputs to all metocean studies, whether for deep-water locations or coastal applications. This paper presents the use of machine learning to calibrate long term metocean time series of wind and wave parameters obtained from numerical models against measurement records, usually covering shorter periods. We present the added value of machine learning compared to standard calibration methods to improve data used as primary input to both operability studies and engineering design studies. Time series of wind and wave parameters obtained from global numerical hindcast data sets are compared to oceanographic buoy measurements. We investigate the improvement brought by machine learning methods on the quality of the calibrated populations for the bulk of the distributions, but also the agreement between the calibrated data and the measurements for extreme events, not only for peak values but also for storm profiles. We evaluate the reliability of the method by comparing the results over different periods at 1 location and with varying length of training, validation and test sets.","PeriodicalId":408227,"journal":{"name":"Volume 5A: Ocean Engineering","volume":"137 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127396021","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigating Hull Blockage and Thruster-Hull Effects on an ASD Tug","authors":"L. Yiew, B. Taskar, Y. Zheng, A. Magee","doi":"10.1115/omae2022-80816","DOIUrl":"https://doi.org/10.1115/omae2022-80816","url":null,"abstract":"\u0000 Interactions between a vessel’s hull and its propulsor are important design and engineering considerations. For vessels equipped with azimuthing propulsors, these interactions are compounded due to the ability of propulsors to direct thrust over a wider arc, even into its own hull. In this study, we examine the interactions between a pair of thrusters and the hull of an azimuthing stern drive (ASD) tug. Specifically, we analyse thruster-on-hull effects, which can materialise as increases in hull drag when flow around the hull is altered by a thruster, or when thrust is vectored towards the hull and impeded by hull surfaces. A series of captive model tests were conducted to evaluate these effects using static and dynamic planar motion mechanism (PMM) tests, in both bare hull and appended hull configurations. Results from this study identify the conditions contributing to thruster-on-hull interactions, and provide further insights into physical mechanisms affecting thruster and hull performances in different flow regimes.","PeriodicalId":408227,"journal":{"name":"Volume 5A: Ocean Engineering","volume":"56 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121546618","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}