Micol Pucci, S. Zanforlin, D. Bellafiore, G. Umgiesser
A routine to predict the performance of cross-flow hydrokinetic turbines, based on the Blade Element Momentum theory, for site assessment purposes is here presented. The routine uses as input the flow data obtained with the open-source marine circulation code SHYFEM. The routine consists in a Double Multiple Stream Tube model making use of 1D flow simplifications for fast analyses. The dynamic stall sub-model and two original sub-models, implemented to include the effects of blade tip losses and the lateral deviation of streamlines approaching the turbine, have been validated versus results of 3D and 2D CFD simulations. As a case study, the tool is applied to an area of the northern Adriatic Sea in order to quickly identify locations with the highest hydrokinetic potential and, at the same time, to find the most efficient turbine aspect ratio and configuration (single or paired turbines) taking into account the bathymetric constraints. The results show that turbines, with short aspect ratio, and paired turbines (with the same overall frontal area of a single rotor) can give the best power outputs thanks to higher flow speeds available at the top of the water column and more favorable Reynolds number and distribution of tip speed ratios along the blade.
{"title":"A Double Multiple Stream Tube (DMST) routine to identify efficient geometries of cross-flow tidal turbines in site assessment analyses","authors":"Micol Pucci, S. Zanforlin, D. Bellafiore, G. Umgiesser","doi":"10.2218/marine2021.6848","DOIUrl":"https://doi.org/10.2218/marine2021.6848","url":null,"abstract":"A routine to predict the performance of cross-flow hydrokinetic turbines, based on the Blade Element Momentum theory, for site assessment purposes is here presented. The routine uses as input the flow data obtained with the open-source marine circulation code SHYFEM. The routine consists in a Double Multiple Stream Tube model making use of 1D flow simplifications for fast analyses. The dynamic stall sub-model and two original sub-models, implemented to include the effects of blade tip losses and the lateral deviation of streamlines approaching the turbine, have been validated versus results of 3D and 2D CFD simulations. As a case study, the tool is applied to an area of the northern Adriatic Sea in order to quickly identify locations with the highest hydrokinetic potential and, at the same time, to find the most efficient turbine aspect ratio and configuration (single or paired turbines) taking into account the bathymetric constraints. The results show that turbines, with short aspect ratio, and paired turbines (with the same overall frontal area of a single rotor) can give the best power outputs thanks to higher flow speeds available at the top of the water column and more favorable Reynolds number and distribution of tip speed ratios along the blade.","PeriodicalId":367395,"journal":{"name":"The 9th Conference on Computational Methods in Marine Engineering (Marine 2021)","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121052049","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}
. Accurate and efficient prediction of extreme ship responses continues to be an important and challenging problem in ship hydrodynamics. Probabilistic frameworks in con-junction with computationally efficient numerical hydrodynamic tools such as volume-based and potential flow methods have been developed that allow researchers and ship designers to better understand extreme events. However, the ability of these tools to represent the physics quantitatively during extreme events is limited and not robust to different problems. There-fore, model testing will continue to be important in analysis, and more emphasis will be placed on high fidelity computational fluid dynamics (CFD) simulations. Experiments and CFD both come at well documented costs and require a systematic approach to target extreme events. The critical wave groups method (CWG) has been implemented with CFD, and the integra-tion of high fidelity simulations with extreme event probabilistic methods has been previously showcased. The implementation of CWG with CFD is achieved by embedding deterministic wave groups into previously run irregular wave trains such that the motion state of the ship at the moment of encountering the wave group is known. Embedding the deterministic wave groups into an irregular wave train results in a composite wave train that can be evaluated with numerical hydrodynamic simulation tools such as CFD, or even a model test. Though the CWG method does allow for less simulation time than a Monte Carlo type approach, the large number of runs required may still be cost-prohibitive. The objective of the present work is to develop an approach where a limited set of expensive simulations or experiments build a time-accurate long short-term memory (LSTM) neural network model that rapidly identifies critical wave groups that lead to a response exceeding a specified threshold. This paper compares the LSTM modeling approach of building a single neural network for all wave groups to establishing an ensemble of neural networks, each responsible for wave groups with specific parameters. The ensemble approach showcases better accuracy, a higher convergence with respect to data quantity, and produces responses that are representative of the CFD simulations.
{"title":"Data-Driven Identification of Critical Wave Groups","authors":"K. Silva, K. Maki","doi":"10.2218/marine2021.6792","DOIUrl":"https://doi.org/10.2218/marine2021.6792","url":null,"abstract":". Accurate and efficient prediction of extreme ship responses continues to be an important and challenging problem in ship hydrodynamics. Probabilistic frameworks in con-junction with computationally efficient numerical hydrodynamic tools such as volume-based and potential flow methods have been developed that allow researchers and ship designers to better understand extreme events. However, the ability of these tools to represent the physics quantitatively during extreme events is limited and not robust to different problems. There-fore, model testing will continue to be important in analysis, and more emphasis will be placed on high fidelity computational fluid dynamics (CFD) simulations. Experiments and CFD both come at well documented costs and require a systematic approach to target extreme events. The critical wave groups method (CWG) has been implemented with CFD, and the integra-tion of high fidelity simulations with extreme event probabilistic methods has been previously showcased. The implementation of CWG with CFD is achieved by embedding deterministic wave groups into previously run irregular wave trains such that the motion state of the ship at the moment of encountering the wave group is known. Embedding the deterministic wave groups into an irregular wave train results in a composite wave train that can be evaluated with numerical hydrodynamic simulation tools such as CFD, or even a model test. Though the CWG method does allow for less simulation time than a Monte Carlo type approach, the large number of runs required may still be cost-prohibitive. The objective of the present work is to develop an approach where a limited set of expensive simulations or experiments build a time-accurate long short-term memory (LSTM) neural network model that rapidly identifies critical wave groups that lead to a response exceeding a specified threshold. This paper compares the LSTM modeling approach of building a single neural network for all wave groups to establishing an ensemble of neural networks, each responsible for wave groups with specific parameters. The ensemble approach showcases better accuracy, a higher convergence with respect to data quantity, and produces responses that are representative of the CFD simulations.","PeriodicalId":367395,"journal":{"name":"The 9th Conference on Computational Methods in Marine Engineering (Marine 2021)","volume":"59 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126412224","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}
. FINN is a dinghy boat used for the Olympics Games. Unlike most of the series involved in Olympics, which are one-design boats, the FINN offers class rules system which allow to propose design enhancements to target specific requirements from sailors. Structural design has been performed using the 3D EXPERIENCE Platform by Dassault-Syst`emes. Trade-off between structural design (composites) and fluid performance (external shape) have been performed over 10000 virtual models and imagine seven different masts to be manufactured by Heol Composites. Each manufactured mast was used for training and competition by the sailors of French National Federation in various conditions, in different sailing areas (France, Italy, Greece, Spain, ...). Advanced tests have been performed on one particular mast to mesure the strains and mast deformation from optical fibre measurements in collaboration with Pixel-Sur-Mer. Those experiments were then used to develop and validate accurate simulation with the mast, boom and sail all modeled in a single Fluid-structural simulation. All this engineering work has been performed from 2018 to 2021. This project leaded to enhancement the performance of sailors in various conditions and helped them to get a better
{"title":"STRUCTURAL AND FLUID DESIGN EXPLORATION TO ENHANCE THE PERFORMANCE OF A FINN MAST FOR THE OLYMPICS GAMES","authors":"PIERRE-YVE Mechin","doi":"10.2218/marine2021.6858","DOIUrl":"https://doi.org/10.2218/marine2021.6858","url":null,"abstract":". FINN is a dinghy boat used for the Olympics Games. Unlike most of the series involved in Olympics, which are one-design boats, the FINN offers class rules system which allow to propose design enhancements to target specific requirements from sailors. Structural design has been performed using the 3D EXPERIENCE Platform by Dassault-Syst`emes. Trade-off between structural design (composites) and fluid performance (external shape) have been performed over 10000 virtual models and imagine seven different masts to be manufactured by Heol Composites. Each manufactured mast was used for training and competition by the sailors of French National Federation in various conditions, in different sailing areas (France, Italy, Greece, Spain, ...). Advanced tests have been performed on one particular mast to mesure the strains and mast deformation from optical fibre measurements in collaboration with Pixel-Sur-Mer. Those experiments were then used to develop and validate accurate simulation with the mast, boom and sail all modeled in a single Fluid-structural simulation. All this engineering work has been performed from 2018 to 2021. This project leaded to enhancement the performance of sailors in various conditions and helped them to get a better","PeriodicalId":367395,"journal":{"name":"The 9th Conference on Computational Methods in Marine Engineering (Marine 2021)","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127967399","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}
. The design and analysis of vessels and wave energy converters requires an under-standing of the nonlinear loads and responses in stochastic waves. A novel mesh-free potential flow methodology is introduced for simulating the response of a floating body with nonlinear Froude-Krylov and hydrostatic e ff ects. The nonlinear fluid forces are cast as volume integrals using Fluid Impulse Theory (FIT). These volume integrals are robustly evaluated using Quasi-Monte Carlo (QMC) integration over an implicit geometry without the need to discretize the hull or free surfaces. The resulting nonlinear equation of motion is solved with an impulse-adapted Chebyshev Picard iteration scheme (I-MCPI). By approximating the nonlinear momentum impulse with a Chebyshev series, the time derivative can be analytically computed, circumventing the numerical sensitivity of finite-di ff erencing. The solution is shown to converge over short parallelized subintervals, and sequentially concatenated to form long time records.
{"title":"A Quasi-Monte Carlo Volume Integration and Chebyshev Picard Iteration Method for Time-Parallel Nonlinear Seakeeping Computations","authors":"David F. H Larson, P. Sclavounos","doi":"10.2218/marine2021.6833","DOIUrl":"https://doi.org/10.2218/marine2021.6833","url":null,"abstract":". The design and analysis of vessels and wave energy converters requires an under-standing of the nonlinear loads and responses in stochastic waves. A novel mesh-free potential flow methodology is introduced for simulating the response of a floating body with nonlinear Froude-Krylov and hydrostatic e ff ects. The nonlinear fluid forces are cast as volume integrals using Fluid Impulse Theory (FIT). These volume integrals are robustly evaluated using Quasi-Monte Carlo (QMC) integration over an implicit geometry without the need to discretize the hull or free surfaces. The resulting nonlinear equation of motion is solved with an impulse-adapted Chebyshev Picard iteration scheme (I-MCPI). By approximating the nonlinear momentum impulse with a Chebyshev series, the time derivative can be analytically computed, circumventing the numerical sensitivity of finite-di ff erencing. The solution is shown to converge over short parallelized subintervals, and sequentially concatenated to form long time records.","PeriodicalId":367395,"journal":{"name":"The 9th Conference on Computational Methods in Marine Engineering (Marine 2021)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134239419","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":"Modification of k-omega Turbulence Model for Ship Flow Prediction","authors":"T. Hino","doi":"10.2218/marine2021.6849","DOIUrl":"https://doi.org/10.2218/marine2021.6849","url":null,"abstract":"","PeriodicalId":367395,"journal":{"name":"The 9th Conference on Computational Methods in Marine Engineering (Marine 2021)","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130982190","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}
the vertical the results The proposed approach the use of a the motions of a submarine when close to the free surface, and to safe operating
本文提出了利用潜艇在接近自由水面时的运动来保证安全运行的方法
{"title":"Prediction of the Vertical Plane Manoeuvring Coefficients for a Submarine when Close to the Surface","authors":"Christopher K Polis, M. Renilson, D. Ranmuthugala","doi":"10.2218/marine2021.6846","DOIUrl":"https://doi.org/10.2218/marine2021.6846","url":null,"abstract":"the vertical the results The proposed approach the use of a the motions of a submarine when close to the free surface, and to safe operating","PeriodicalId":367395,"journal":{"name":"The 9th Conference on Computational Methods in Marine Engineering (Marine 2021)","volume":"113 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133515354","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}
. This paper presents computations for the flow around the Japanese Bulk Carrier (JBC) international benchmark case operating in calm-water. The flow is computed with the OpenFOAM opensource software. The purpose to perform the computations is to participate in an open validation study where the grids and results are provided together with the paper in a special session. Results of the wave elevation, force on the hull, and velocity in the stern region are provided on a series of seven computational grids.
{"title":"URANS SIMULATIONS OF THE JAPAN BULK CARRIER BENCHMARK TEST CASE","authors":"August Sturm, K. Maki","doi":"10.2218/marine2021.6788","DOIUrl":"https://doi.org/10.2218/marine2021.6788","url":null,"abstract":". This paper presents computations for the flow around the Japanese Bulk Carrier (JBC) international benchmark case operating in calm-water. The flow is computed with the OpenFOAM opensource software. The purpose to perform the computations is to participate in an open validation study where the grids and results are provided together with the paper in a special session. Results of the wave elevation, force on the hull, and velocity in the stern region are provided on a series of seven computational grids.","PeriodicalId":367395,"journal":{"name":"The 9th Conference on Computational Methods in Marine Engineering (Marine 2021)","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128865564","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}
P. Bot, Dimitri Voisin, Antoine Soulier, C. Braud, Jacques AN Astolfi
. The performance of lifting bodies such as hydrofoils is determined by the flow state and particular attention should be paid to flow separation, as this greatly affects the generated lift and drag. Sailors are used to look at telltales (woolies) to trim their sails or steer their yacht. A French company developed an electronic telltale for sails based on a strain gauge activated by a silicon strand, with the appropriate signal processing to deliver the same information as a classical wool-made telltale, basically attached or separated flow. This new sensor proved useful when woolies are not visible or to deliver a signal to feed a control system, such as the autopilot for example. It was also applied to wind turbines to control the blade pitch. Mer Agit´ee is now developing an equivalent hydrodynamic e-Telltale to be used on hydrofoils and rudders to help trimming and controlling. The present work presents the investigation of a foil section fitted with this new sensor in a water tunnel, combining force and PIV measurements with the sensor signal, on a wide range of angle of attack. Results show that the hydro e-Telltale enables detecting the flow separation and anticipate stall, and possibly allows for detecting the boundary layer transition to turbulence. In many cases of fluid flow over a lifting body, it is interesting to get some real-time feedback from the flow in order to help optimizing performance and controlling the system. The feedback from this new sensor could be used in a closed-loop controlling system, for
{"title":"A NEW SENSOR TO CHARACTERIZE FLOW SEPARATION ON A HYDROFOIL","authors":"P. Bot, Dimitri Voisin, Antoine Soulier, C. Braud, Jacques AN Astolfi","doi":"10.2218/marine2021.6779","DOIUrl":"https://doi.org/10.2218/marine2021.6779","url":null,"abstract":". The performance of lifting bodies such as hydrofoils is determined by the flow state and particular attention should be paid to flow separation, as this greatly affects the generated lift and drag. Sailors are used to look at telltales (woolies) to trim their sails or steer their yacht. A French company developed an electronic telltale for sails based on a strain gauge activated by a silicon strand, with the appropriate signal processing to deliver the same information as a classical wool-made telltale, basically attached or separated flow. This new sensor proved useful when woolies are not visible or to deliver a signal to feed a control system, such as the autopilot for example. It was also applied to wind turbines to control the blade pitch. Mer Agit´ee is now developing an equivalent hydrodynamic e-Telltale to be used on hydrofoils and rudders to help trimming and controlling. The present work presents the investigation of a foil section fitted with this new sensor in a water tunnel, combining force and PIV measurements with the sensor signal, on a wide range of angle of attack. Results show that the hydro e-Telltale enables detecting the flow separation and anticipate stall, and possibly allows for detecting the boundary layer transition to turbulence. In many cases of fluid flow over a lifting body, it is interesting to get some real-time feedback from the flow in order to help optimizing performance and controlling the system. The feedback from this new sensor could be used in a closed-loop controlling system, for","PeriodicalId":367395,"journal":{"name":"The 9th Conference on Computational Methods in Marine Engineering (Marine 2021)","volume":"89 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133715947","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}
Momchil Terziev, T. Tezdogan, A. Incecik, C. De Marco Muscat-Fenech
The field of ship hydrodynamics in confined water has received increased attention by the academic community in recent years. Nevertheless, a number of phenomena occurring in confined waters are yet to be examined using high fidelity Computational Fluid Dynamics (CFD) or experimentally. One particular case is the presence of sheared currents and their impact on the performance of a ship. Such currents can be generated in confined waters as a result of the natural flow of water in rivers or due to the action of tidal influences in long canals. Alternatively, due to the short fetch of many inland waterways, the action of wind may result in the production of a sheared current. This work aims to investigate these effects by making use of a commercially available Reynolds Averaged Navier-Stokes (RANS) solver. A number of current profiles are numerically modelled to determine their influence on ship performance and the manner in which ship waves interact with the background current. The present study will contribute to the understanding of restricted water effects by revealing the impact of shear currents on ship performance
{"title":"Investigating the influence of sheared currents on ship hydrodynamics in confined water using Computational Fluid Dynamics","authors":"Momchil Terziev, T. Tezdogan, A. Incecik, C. De Marco Muscat-Fenech","doi":"10.2218/marine2021.6778","DOIUrl":"https://doi.org/10.2218/marine2021.6778","url":null,"abstract":"The field of ship hydrodynamics in confined water has received increased attention by the academic community in recent years. Nevertheless, a number of phenomena occurring in confined waters are yet to be examined using high fidelity Computational Fluid Dynamics (CFD) or experimentally. One particular case is the presence of sheared currents and their impact on the performance of a ship. Such currents can be generated in confined waters as a result of the natural flow of water in rivers or due to the action of tidal influences in long canals. Alternatively, due to the short fetch of many inland waterways, the action of wind may result in the production of a sheared current. This work aims to investigate these effects by making use of a commercially available Reynolds Averaged Navier-Stokes (RANS) solver. A number of current profiles are numerically modelled to determine their influence on ship performance and the manner in which ship waves interact with the background current. The present study will contribute to the understanding of restricted water effects by revealing the impact of shear currents on ship performance","PeriodicalId":367395,"journal":{"name":"The 9th Conference on Computational Methods in Marine Engineering (Marine 2021)","volume":"99 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115716574","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}
Considering the evolution of the racing sailing yacht in the last decade, we have seen the increasingly extensive use of hydrofoil systems able to support and fly boats over the free surface. The great advantage of these systems is to increase comfort in navigation and to reduce drag. Unfortunately, these systems, in addition to the great advantages in terms of efficiency, bring with them problems linked above all to their functioning between two fluids, air and water. In fact, the hydrofoils systems are subjected to natural ventilation and cavitation. In particular, the phenomenon of ventilation is typically present when there is a surface piercing strut that includes air and water in particular conditions of use; the geometry and physical conditions allow the creation of a region with a lower pressure than the atmospheric one, which then causes a cavity connected to the external environment. Ventilation is therefore an important phenomenon to be taken into consideration when designing hydrofoil appendages for racing boats and understanding the phenomena is fundamental for the success of the project. Using the numerical simulation, in this case CFD, it is possible to investigate the favorable conditions of formation of the ventilated cavity for the conditions of use of a foil appendage. In order to use CFD as a forecasting and design tool, it was necessary to carry out a validation campaign using a reference benchmark; the results of the investigation made it possible to fine-tune the CFD tool to be able to predict the phenomenon of ventilation in a robust manner. By applying the method developed on a kite foil surface piercing strut case, it was possible to estimate the performance differences of 2D sections and planform shapes to understand the ventilation tolerance of new candidate designs for construction. Furthermore, it was possible to visualize the ventilation trend by means of numerical indices able to visually show the behavior of one design compared to another. These methods could be used together with low fidelity methods (VLM, panel code, lifting line) to build response surfaces or surrogate models to be used in performances prediction..
{"title":"KITE FOIL MAST VENTILATION STUDY","authors":"S. Bartesaghi, Giorgio Provinciali, Franco Lovato","doi":"10.2218/marine2021.6828","DOIUrl":"https://doi.org/10.2218/marine2021.6828","url":null,"abstract":"Considering the evolution of the racing sailing yacht in the last decade, we have seen the increasingly extensive use of hydrofoil systems able to support and fly boats over the free surface. The great advantage of these systems is to increase comfort in navigation and to reduce drag. Unfortunately, these systems, in addition to the great advantages in terms of efficiency, bring with them problems linked above all to their functioning between two fluids, air and water. In fact, the hydrofoils systems are subjected to natural ventilation and cavitation. In particular, the phenomenon of ventilation is typically present when there is a surface piercing strut that includes air and water in particular conditions of use; the geometry and physical conditions allow the creation of a region with a lower pressure than the atmospheric one, which then causes a cavity connected to the external environment. Ventilation is therefore an important phenomenon to be taken into consideration when designing hydrofoil appendages for racing boats and understanding the phenomena is fundamental for the success of the project. Using the numerical simulation, in this case CFD, it is possible to investigate the favorable conditions of formation of the ventilated cavity for the conditions of use of a foil appendage. In order to use CFD as a forecasting and design tool, it was necessary to carry out a validation campaign using a reference benchmark; the results of the investigation made it possible to fine-tune the CFD tool to be able to predict the phenomenon of ventilation in a robust manner. By applying the method developed on a kite foil surface piercing strut case, it was possible to estimate the performance differences of 2D sections and planform shapes to understand the ventilation tolerance of new candidate designs for construction. Furthermore, it was possible to visualize the ventilation trend by means of numerical indices able to visually show the behavior of one design compared to another. These methods could be used together with low fidelity methods (VLM, panel code, lifting line) to build response surfaces or surrogate models to be used in performances prediction..","PeriodicalId":367395,"journal":{"name":"The 9th Conference on Computational Methods in Marine Engineering (Marine 2021)","volume":"71 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127629723","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}
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