Volume 9: Rodney Eatock Taylor Honoring Symposium on Marine and Offshore Hydrodynamics; Takeshi Kinoshita Honoring Symposium on Offshore Technology最新文献
T. Ikoma, Y. Kihara, Shota Hirai, Y. Aida, K. Masuda, H. Eto
Oscillating water column (OWC) types of wave energy converters have still several issues to be studied because system including wave-air-turbine interaction is complex. Besides, scale effects between small scale models and full scale models have not been definite. Although the effect in initial design of OWC devices might been able to be ignored, it is important to understand its characteristics exactly. The present study carried out forced oscillation tests in a water tank corresponding to the radiation problem. Three models whose scale are 1/1, 1/2 and 1/4 were used. In the forced oscillation test, we measured mean water elevation in an airchamber to predict the air flow rate and air pressure inside of the airchamber. From the mean water elevation and the air pressure, the primary power conversion was calculated. As a result, the pressure and the elevation were affected by not only the scale reduction but also the difference of airchamber volume. Variation of the volume of an airchamber affected on hydrodynamic performance sensitively.
{"title":"A Basic Study on Influence of Airchamber Volume on OWC Models to Power Conversion Performance","authors":"T. Ikoma, Y. Kihara, Shota Hirai, Y. Aida, K. Masuda, H. Eto","doi":"10.1115/omae2019-95925","DOIUrl":"https://doi.org/10.1115/omae2019-95925","url":null,"abstract":"\u0000 Oscillating water column (OWC) types of wave energy converters have still several issues to be studied because system including wave-air-turbine interaction is complex. Besides, scale effects between small scale models and full scale models have not been definite. Although the effect in initial design of OWC devices might been able to be ignored, it is important to understand its characteristics exactly. The present study carried out forced oscillation tests in a water tank corresponding to the radiation problem. Three models whose scale are 1/1, 1/2 and 1/4 were used. In the forced oscillation test, we measured mean water elevation in an airchamber to predict the air flow rate and air pressure inside of the airchamber. From the mean water elevation and the air pressure, the primary power conversion was calculated. As a result, the pressure and the elevation were affected by not only the scale reduction but also the difference of airchamber volume. Variation of the volume of an airchamber affected on hydrodynamic performance sensitively.","PeriodicalId":120800,"journal":{"name":"Volume 9: Rodney Eatock Taylor Honoring Symposium on Marine and Offshore Hydrodynamics; Takeshi Kinoshita Honoring Symposium on Offshore Technology","volume":"61 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114581464","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}
L. Cui, Y. Zheng, Yinggang Li, Ling Zhu, Mingsheng Chen
Ships sailing in the sea may encounter collision, grounding or projectile impacting accidents, which may cause hull damage and subsequent compartment flooding. Due to the effect of the flooding water induced moment and the restoring moment, the damaged ship may have inclination and rolling motion. When the inclination or the rolling motion is too large, it may affect the safety and survivability of ship in navigation and cause severe casualties and property losses. In order to increase the navigation safety and survivability of the damaged ship, a numerical model is established based on the potential flow theory to investigate the seakeeping performance of the damaged ship in two scenarios, i.e., the case before ship damaged, and the case when the damaged ship reaching a relatively stable floating state. The heave, pitch and roll motion responses and corresponding wave-induced loads acting on the ship are analyzed in regular waves. In addition, the effects of the navigation speed and the wave direction on the seakeeping performance are also investigated.
{"title":"Numerical Study on Seakeeping Performance of a Damaged Ship","authors":"L. Cui, Y. Zheng, Yinggang Li, Ling Zhu, Mingsheng Chen","doi":"10.1115/omae2019-96193","DOIUrl":"https://doi.org/10.1115/omae2019-96193","url":null,"abstract":"\u0000 Ships sailing in the sea may encounter collision, grounding or projectile impacting accidents, which may cause hull damage and subsequent compartment flooding. Due to the effect of the flooding water induced moment and the restoring moment, the damaged ship may have inclination and rolling motion. When the inclination or the rolling motion is too large, it may affect the safety and survivability of ship in navigation and cause severe casualties and property losses. In order to increase the navigation safety and survivability of the damaged ship, a numerical model is established based on the potential flow theory to investigate the seakeeping performance of the damaged ship in two scenarios, i.e., the case before ship damaged, and the case when the damaged ship reaching a relatively stable floating state. The heave, pitch and roll motion responses and corresponding wave-induced loads acting on the ship are analyzed in regular waves. In addition, the effects of the navigation speed and the wave direction on the seakeeping performance are also investigated.","PeriodicalId":120800,"journal":{"name":"Volume 9: Rodney Eatock Taylor Honoring Symposium on Marine and Offshore Hydrodynamics; Takeshi Kinoshita Honoring Symposium on Offshore Technology","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121847620","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}
In this paper, we report the proposal and development of the numerical model. The model applies to two and three dimensional problems. We introduce the model to the MPS method which is a kind of particle method, and discuss applicability of the model on numerical test of aerial physical pendulum in free torque load; the present model was compared with the theoretical solution by the 4th order Runge-Kutta method. As a result, we confirmed the good reproducibility of the model. And we can say that the model is suitable for analyzing the problem of physical pendulum. Secondary, we examine the practicability of this model in the regular wave from the calculation results. The tests are examined by a two-dimensional problem in order to reduce calculation cost. In addition, we conducted fluid-structure interaction analysis using the present model and confirmed the applicability of its model to fluid field analysis.
{"title":"Fundamental Study on Development on Numerical Method for Evaluation of Wave Power Generating Systems With Pendulum Type by the Particle Method","authors":"Kazuki Murata, C. Rheem, T. Ikoma","doi":"10.1115/omae2019-95869","DOIUrl":"https://doi.org/10.1115/omae2019-95869","url":null,"abstract":"\u0000 In this paper, we report the proposal and development of the numerical model. The model applies to two and three dimensional problems. We introduce the model to the MPS method which is a kind of particle method, and discuss applicability of the model on numerical test of aerial physical pendulum in free torque load; the present model was compared with the theoretical solution by the 4th order Runge-Kutta method. As a result, we confirmed the good reproducibility of the model. And we can say that the model is suitable for analyzing the problem of physical pendulum.\u0000 Secondary, we examine the practicability of this model in the regular wave from the calculation results. The tests are examined by a two-dimensional problem in order to reduce calculation cost. In addition, we conducted fluid-structure interaction analysis using the present model and confirmed the applicability of its model to fluid field analysis.","PeriodicalId":120800,"journal":{"name":"Volume 9: Rodney Eatock Taylor Honoring Symposium on Marine and Offshore Hydrodynamics; Takeshi Kinoshita Honoring Symposium on Offshore Technology","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131680760","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}
Over the last decade, the importance of considering the effects of waves on the maneuvering characteristics of ships has been widely recognized. This paper presents the application of a recently developed nonlinear body-exact scheme (Subramanian, Rakesh, and Beck (2018)) to directly simulate the maneuvering characteristics of a container ship in calm water and in regular waves. In the present body-exact scheme, the perturbation free surface boundary conditions are transferred to a representative incident wave surface at each station at each time. The hydrodynamic forces are computed on the exact instantaneous wetted surface formed by the intersection of the incident wave surface with the exact body position at each time. It is proposed that this model will not only improve first order sea loads but also the higher order drift force predictions which are critical for determining the trajectory of a maneuvering vessel in a seaway. The strip theory formulation has been found to be numerically stable, robust and computationally efficient, which are all critical aspects when performing long time maneuvering simulations. The hull maneuvering, rudder and propeller forces are adopted from standard systems-based approaches that are used to predict calm water maneuvers. Care is taken to ensure that ideal fluid effects are separated from viscous effects and not double counted. Results are presented for turning circle maneuvers in calm water and regular waves incident at various headings and wavelengths. The numerical results are compared with available experiments.
在过去的十年中，考虑波浪对船舶机动特性影响的重要性已被广泛认识。本文介绍了最近开发的非线性体精确格式(Subramanian, Rakesh, and Beck(2018))的应用，以直接模拟集装箱船在平静水域和规则波浪中的机动特性。在目前的体精确格式中，将摄动自由表面边界条件传递到每个站点在每个时间点的代表性入射波表面。在每次入射波面与确切的物体位置相交形成的精确瞬时润湿表面上计算水动力。该模型不仅可以改善一阶海荷载，而且可以改善高阶漂移力的预测，而高阶漂移力是确定海上机动船舶轨迹的关键。条带理论公式具有数值稳定性、鲁棒性和计算效率，这些都是进行长时间机动模拟的关键方面。船体机动、方向舵和螺旋桨力采用了用于预测静水机动的标准系统方法。要注意确保将理想流体效应与粘性效应分开，并且不重复计算。给出了在平静水域和不同航向和波长入射的规则波浪中回转机动的结果。数值结果与已有实验结果进行了比较。
{"title":"An Improved Body-Exact Method to Predict the Maneuvering of Ships in a Seaway","authors":"R. Subramanian, R. Beck","doi":"10.1115/omae2019-96441","DOIUrl":"https://doi.org/10.1115/omae2019-96441","url":null,"abstract":"\u0000 Over the last decade, the importance of considering the effects of waves on the maneuvering characteristics of ships has been widely recognized. This paper presents the application of a recently developed nonlinear body-exact scheme (Subramanian, Rakesh, and Beck (2018)) to directly simulate the maneuvering characteristics of a container ship in calm water and in regular waves. In the present body-exact scheme, the perturbation free surface boundary conditions are transferred to a representative incident wave surface at each station at each time. The hydrodynamic forces are computed on the exact instantaneous wetted surface formed by the intersection of the incident wave surface with the exact body position at each time. It is proposed that this model will not only improve first order sea loads but also the higher order drift force predictions which are critical for determining the trajectory of a maneuvering vessel in a seaway. The strip theory formulation has been found to be numerically stable, robust and computationally efficient, which are all critical aspects when performing long time maneuvering simulations. The hull maneuvering, rudder and propeller forces are adopted from standard systems-based approaches that are used to predict calm water maneuvers. Care is taken to ensure that ideal fluid effects are separated from viscous effects and not double counted. Results are presented for turning circle maneuvers in calm water and regular waves incident at various headings and wavelengths. The numerical results are compared with available experiments.","PeriodicalId":120800,"journal":{"name":"Volume 9: Rodney Eatock Taylor Honoring Symposium on Marine and Offshore Hydrodynamics; Takeshi Kinoshita Honoring Symposium on Offshore Technology","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130752815","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}
Xinxin Wang, Liu-yi Huang, Yanli Tang, F. Zhao, Peng Sun
The stranded rope is one of the important components of the fishery aquaculture equipment. We investigate the fluid flow through two-dimensional stranded rope by direct simulation of the Navier-Stokes equations. We show that for different kinds of stranded rope structures, there are significant differences in hydrodynamic performance. This paper established a numerical model of unsteady flow past the stranded rope based on the Navier-Stokes equation and Morison formulas to study the hydrodynamic characteristics of three-stranded rope, four-stranded rope, and seven-stranded rope, respectively. The turbulence flow was simulated using Standard k-ε model and Shear-Stress Transport k-ω (SST) model. The flow distribution strongly depends on the Reynolds number, a range of 3,900 and 30,000. With increasing Reynolds number, the alternate eddy formation and shedding were repeated behind the stranded ropes. Such parameters of hydrodynamic characteristics of multiple stranded ropes were calculated as the lift and drag coefficients, and vortex shedding frequencies. The numerical simulation results presented flow performances of different cross sections (a, b, c, d) at different Reynolds numbers. However, Reynolds number has no significant impact on the Strouhal number for the same attack angle of the stranded rope.
{"title":"Two-Dimensional Numerical Simulation of Vortex Shedding of Multiple Stranded Ropes","authors":"Xinxin Wang, Liu-yi Huang, Yanli Tang, F. Zhao, Peng Sun","doi":"10.1115/omae2019-95225","DOIUrl":"https://doi.org/10.1115/omae2019-95225","url":null,"abstract":"\u0000 The stranded rope is one of the important components of the fishery aquaculture equipment. We investigate the fluid flow through two-dimensional stranded rope by direct simulation of the Navier-Stokes equations. We show that for different kinds of stranded rope structures, there are significant differences in hydrodynamic performance. This paper established a numerical model of unsteady flow past the stranded rope based on the Navier-Stokes equation and Morison formulas to study the hydrodynamic characteristics of three-stranded rope, four-stranded rope, and seven-stranded rope, respectively. The turbulence flow was simulated using Standard k-ε model and Shear-Stress Transport k-ω (SST) model. The flow distribution strongly depends on the Reynolds number, a range of 3,900 and 30,000. With increasing Reynolds number, the alternate eddy formation and shedding were repeated behind the stranded ropes. Such parameters of hydrodynamic characteristics of multiple stranded ropes were calculated as the lift and drag coefficients, and vortex shedding frequencies. The numerical simulation results presented flow performances of different cross sections (a, b, c, d) at different Reynolds numbers. However, Reynolds number has no significant impact on the Strouhal number for the same attack angle of the stranded rope.","PeriodicalId":120800,"journal":{"name":"Volume 9: Rodney Eatock Taylor Honoring Symposium on Marine and Offshore Hydrodynamics; Takeshi Kinoshita Honoring Symposium on Offshore Technology","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131096367","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}
An analysis of the flow and of the vertical transfer of the horizontal momentum induced by the breaking of modulated wave trains in wind and no-wind conditions is presented. The study is based on the results of two-dimensional numerical simulation of the Navier-Stokes equations for two-phase flow. The open source Gerris flow solver has been used, which employs a Volume of Fluid technique to capture the air-water interface. The breaking is induced through the Benjamin-Feir instability mechanism. The numerical simulations cover the entire range from the initial development of the instability, the breaking phase and the post-breaking evolution. In order to investigate the role played by the wind, a uniform wind profile, twice the phase speed, is initialized in the air phase and it is left to evolve while interacting with the wave system. Results in terms of averaged horizontal velocity and vertical flux of horizontal momentum are presented. It is shown that in the wind case the backward stresses induced at the wave troughs as a consequence of the flow separation at the crest influence significantly the flow in the upper water layer, particularly in the pre-breaking phase. No substantial differences are found between the wind and no-wind solutions in terms of the vertical transfer of horizontal momentum in the lower water layer. The vertical flux of horizontal momentum in air is consistent with the velocity reduction occurring in the wind case in the early stage.
{"title":"Analysis of the Momentum Transfer Operated by the Breaking in Modulated Wave Trains in Wind and No-Wind Conditions","authors":"A. Iafrati, M. Falchi","doi":"10.1115/omae2019-95756","DOIUrl":"https://doi.org/10.1115/omae2019-95756","url":null,"abstract":"\u0000 An analysis of the flow and of the vertical transfer of the horizontal momentum induced by the breaking of modulated wave trains in wind and no-wind conditions is presented. The study is based on the results of two-dimensional numerical simulation of the Navier-Stokes equations for two-phase flow. The open source Gerris flow solver has been used, which employs a Volume of Fluid technique to capture the air-water interface.\u0000 The breaking is induced through the Benjamin-Feir instability mechanism. The numerical simulations cover the entire range from the initial development of the instability, the breaking phase and the post-breaking evolution. In order to investigate the role played by the wind, a uniform wind profile, twice the phase speed, is initialized in the air phase and it is left to evolve while interacting with the wave system.\u0000 Results in terms of averaged horizontal velocity and vertical flux of horizontal momentum are presented. It is shown that in the wind case the backward stresses induced at the wave troughs as a consequence of the flow separation at the crest influence significantly the flow in the upper water layer, particularly in the pre-breaking phase. No substantial differences are found between the wind and no-wind solutions in terms of the vertical transfer of horizontal momentum in the lower water layer. The vertical flux of horizontal momentum in air is consistent with the velocity reduction occurring in the wind case in the early stage.","PeriodicalId":120800,"journal":{"name":"Volume 9: Rodney Eatock Taylor Honoring Symposium on Marine and Offshore Hydrodynamics; Takeshi Kinoshita Honoring Symposium on Offshore Technology","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133690199","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}
S. Hirabayashi, M. Cicolin, Rodolfo T. Gonçalves, G. Assi, Hideyuki Suzuki
The effect of wake interaction on the hydrodynamic force was experimentally investigated. A scaled platform model with four columns was subjected to a current in the circulating water channel with constant velocity. The diameter of each column was 75 mm, and the aspect ratio (defined by the ratio between the column draft and diameter) was 1.5. The spacing ratios, (defined by the ratio between the distance of column centers and diameter) were 3 and 4. The platform was forced to oscillate with different frequencies and amplitudes. Flow around columns was measured by using Particle Image Velocimetry (PIV). The difference of hydrodynamic forces on each column was discussed concerning the effect of wake interaction among columns.
{"title":"Analysis of Wake Interaction of Oscillating Platform With Four Columns","authors":"S. Hirabayashi, M. Cicolin, Rodolfo T. Gonçalves, G. Assi, Hideyuki Suzuki","doi":"10.1115/omae2019-95749","DOIUrl":"https://doi.org/10.1115/omae2019-95749","url":null,"abstract":"\u0000 The effect of wake interaction on the hydrodynamic force was experimentally investigated. A scaled platform model with four columns was subjected to a current in the circulating water channel with constant velocity. The diameter of each column was 75 mm, and the aspect ratio (defined by the ratio between the column draft and diameter) was 1.5. The spacing ratios, (defined by the ratio between the distance of column centers and diameter) were 3 and 4. The platform was forced to oscillate with different frequencies and amplitudes. Flow around columns was measured by using Particle Image Velocimetry (PIV). The difference of hydrodynamic forces on each column was discussed concerning the effect of wake interaction among columns.","PeriodicalId":120800,"journal":{"name":"Volume 9: Rodney Eatock Taylor Honoring Symposium on Marine and Offshore Hydrodynamics; Takeshi Kinoshita Honoring Symposium on Offshore Technology","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127889333","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}
A 2D nonlinear numerical wave tank is developed to simulate the motion responses of a moored floating body in waves which may experience strongly nonlinear wave-body interactions. The numerical solver is based on a Boundary Element Method which has been developed to solve strongly nonlinear hydrodynamic problems. The method is further developed in this paper to simulate a floating body in waves, where horizontal, vertical and rotational motions can be calculated. An effective algorithm is implemented to separate the added mass forces from the total hydrodynamic forces, thus to make the time domain solution converge more easily. The numerical results for a horizontal circular cylinder in waves are compared with linear theory for small wave steepness for verification and further compared with published model tests and CFD results for high wave steepness as validations.
{"title":"A 2D Nonlinear Numerical Wave Tank With a Moored Floating Body","authors":"Hui Sun, J. B. Helmers","doi":"10.1115/omae2019-96669","DOIUrl":"https://doi.org/10.1115/omae2019-96669","url":null,"abstract":"\u0000 A 2D nonlinear numerical wave tank is developed to simulate the motion responses of a moored floating body in waves which may experience strongly nonlinear wave-body interactions. The numerical solver is based on a Boundary Element Method which has been developed to solve strongly nonlinear hydrodynamic problems. The method is further developed in this paper to simulate a floating body in waves, where horizontal, vertical and rotational motions can be calculated. An effective algorithm is implemented to separate the added mass forces from the total hydrodynamic forces, thus to make the time domain solution converge more easily. The numerical results for a horizontal circular cylinder in waves are compared with linear theory for small wave steepness for verification and further compared with published model tests and CFD results for high wave steepness as validations.","PeriodicalId":120800,"journal":{"name":"Volume 9: Rodney Eatock Taylor Honoring Symposium on Marine and Offshore Hydrodynamics; Takeshi Kinoshita Honoring Symposium on Offshore Technology","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128485036","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}
In the present study, the hydrodynamic performance of a novel and efficient concept of a floating Oscillating Water Column device has been investigated. The new concept consists of two chambers that are placed in the upstream (fore chamber) and in the downstream (rear chamber) with respect to the incident wave direction. The rear chamber acts mainly similar to a Backward Bent Duct Buoy system, while the design of the fore chamber follows conventional types of Oscillating Water Column systems with the harbour plates (bottom plate as well as side plates) elongated outside of the fore chamber. The primary efficiency of the devised concept has been investigated in the frequency domain. In this context, to solve the corresponding diffraction and radiation problems due to the influence of the air pressure inside the chambers as well as motions of the body, an in-house code has been developed in 2D using the Boundary Element Method based on linear wave theory. The obtained numerical results show that the introduced concept has advanced hydrodynamic efficiency in a broad range of waves.
{"title":"Hydrodynamic Investigation of a Novel Concept of OWC Type Wave Energy Converter Device","authors":"K. Rezanejad, Carlos Soares","doi":"10.1115/omae2019-96510","DOIUrl":"https://doi.org/10.1115/omae2019-96510","url":null,"abstract":"\u0000 In the present study, the hydrodynamic performance of a novel and efficient concept of a floating Oscillating Water Column device has been investigated. The new concept consists of two chambers that are placed in the upstream (fore chamber) and in the downstream (rear chamber) with respect to the incident wave direction. The rear chamber acts mainly similar to a Backward Bent Duct Buoy system, while the design of the fore chamber follows conventional types of Oscillating Water Column systems with the harbour plates (bottom plate as well as side plates) elongated outside of the fore chamber. The primary efficiency of the devised concept has been investigated in the frequency domain. In this context, to solve the corresponding diffraction and radiation problems due to the influence of the air pressure inside the chambers as well as motions of the body, an in-house code has been developed in 2D using the Boundary Element Method based on linear wave theory. The obtained numerical results show that the introduced concept has advanced hydrodynamic efficiency in a broad range of waves.","PeriodicalId":120800,"journal":{"name":"Volume 9: Rodney Eatock Taylor Honoring Symposium on Marine and Offshore Hydrodynamics; Takeshi Kinoshita Honoring Symposium on Offshore Technology","volume":"120 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124633543","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}
Waves are primarily important for the tidal current power generation as they relate not only to the wave load acting on the tidal turbine but also to the installation/maintenance cost of the device through the workable day rate at the sea. Generally, the tidal current power site is in a narrow strait, and the wave characteristics are strongly dependent on the place. Also, there are few data itself. So, we conducted the wave observation in Naru Strait, Goto City, Nagasaki, where the tidal current power project by the Ministry of Environment is in progress. An AWAC (Acoustic Wave and Current Meter) was deployed on the sea bottom of 20m depth in Naru Strait on 18 May and recovered on 12 November, 2017. The wave data obtained for about 6 months were analyzed as wave spectra and mean directions by the records of surface elevation together with tidal current velocity. In particular, the changes of wave amplitude by the tidal current and the storms including typhoon passing are presented.
{"title":"Observation of Waves in Naru Strait, Goto, Nagasaki, a Tidal Current Test Site","authors":"Y. Kyozuka","doi":"10.1115/omae2019-96652","DOIUrl":"https://doi.org/10.1115/omae2019-96652","url":null,"abstract":"\u0000 Waves are primarily important for the tidal current power generation as they relate not only to the wave load acting on the tidal turbine but also to the installation/maintenance cost of the device through the workable day rate at the sea. Generally, the tidal current power site is in a narrow strait, and the wave characteristics are strongly dependent on the place. Also, there are few data itself. So, we conducted the wave observation in Naru Strait, Goto City, Nagasaki, where the tidal current power project by the Ministry of Environment is in progress.\u0000 An AWAC (Acoustic Wave and Current Meter) was deployed on the sea bottom of 20m depth in Naru Strait on 18 May and recovered on 12 November, 2017. The wave data obtained for about 6 months were analyzed as wave spectra and mean directions by the records of surface elevation together with tidal current velocity. In particular, the changes of wave amplitude by the tidal current and the storms including typhoon passing are presented.","PeriodicalId":120800,"journal":{"name":"Volume 9: Rodney Eatock Taylor Honoring Symposium on Marine and Offshore Hydrodynamics; Takeshi Kinoshita Honoring Symposium on Offshore Technology","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121746293","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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