Comparing to Φ-type and H-type VAWT (Vertical Axis Wind Turbine), the amplitude changes of the aerodynamics acting on Helical-type VAWT are much smaller, so Helical-type VAWT has advantages in steady output power and avoiding fatigue of structure. Considering the characteristic of helical-type VAWT, this paper modifies the semi empirical method of calculating aerodynamic loads and compares with CFD results. A comparison is presented between CFD results and experiment results to confirm the model used in CFD. Single parameter analysis and muti-parameters analysis are carried out to study the influence of structural parameters on the dynamic torque. Based on an objective output power as 5MW, the parameters of wind turbine are adjusted, and optimal values of these parameters are determined.
{"title":"The Aerodynamic Analysis of Helical-Type VAWT With Semi Empirical and CFD Method","authors":"Yingge Guo, Li-qin Liu, Xin Lv, You-gang Tang","doi":"10.1115/omae2019-95207","DOIUrl":"https://doi.org/10.1115/omae2019-95207","url":null,"abstract":"\u0000 Comparing to Φ-type and H-type VAWT (Vertical Axis Wind Turbine), the amplitude changes of the aerodynamics acting on Helical-type VAWT are much smaller, so Helical-type VAWT has advantages in steady output power and avoiding fatigue of structure. Considering the characteristic of helical-type VAWT, this paper modifies the semi empirical method of calculating aerodynamic loads and compares with CFD results. A comparison is presented between CFD results and experiment results to confirm the model used in CFD. Single parameter analysis and muti-parameters analysis are carried out to study the influence of structural parameters on the dynamic torque. Based on an objective output power as 5MW, the parameters of wind turbine are adjusted, and optimal values of these parameters are determined.","PeriodicalId":306681,"journal":{"name":"Volume 10: Ocean Renewable Energy","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130646471","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 main drivers for the continued decarbonisation of the global energy market are renewable energy sources. Moreover, the leading technological solutions to achieve this are offshore wind turbines. As installed capacity has been increasing rapidly and shallow water near shore sites are exhausted, projects will need to be developed further from shore and often in deeper waters, which will pose greater technical challenges and constrain efforts to reduce costs. Current floating platform solutions such as the spar and semi-submersible rely on large amounts of ballast and complex structural designs with active stabilisation systems for stability of the floating offshore wind turbine platform (FOWT). The primary focus of this study is to present a design concept and mooring arrangement for an alternative floating platform solution that places emphasis on the mooring system to achieve stability for a FOWT. The tension leg buoy (TLB) is designed to support future 10MW offshore wind turbine generators. This paper presents the numerical methodology used for a coupled hydro-elastic analysis of the floater and mooring system under combined wind, wave and current effects. A concept TLB design is presented and its platform motion and mooring line tension characteristics are analysed for a three-hour time domain simulation representing operating and survival conditions in the northern North Sea with water depths of 110 metres. The importance of wave drift forces and the other non-linear excitation forces in the concept design stage are evaluated by comparing the motion and tension responses of three different numerical simulation cases with increasing numerical complexity. The preliminary TLB system design demonstrated satisfactory motion response for the operation of a FOWT and survival in a 100-year storm condition. The results show that accounting for second-order effect is vital in terms of having a clear understanding of the full behaviour of the system and the detailed response characteristics in operational and survival conditions. Extreme loads are significantly reduced when accounting for the second-order effects. This can be a key aspect to not overdesign the system and consequently achieve significant cost savings.
{"title":"Coupled Numerical Analysis of a Concept TLB Type Floating Offshore Wind Turbine","authors":"Iman Ramzanpoor, M. Nuernberg, L. Tao","doi":"10.1115/OMAE2019-95244","DOIUrl":"https://doi.org/10.1115/OMAE2019-95244","url":null,"abstract":"\u0000 The main drivers for the continued decarbonisation of the global energy market are renewable energy sources. Moreover, the leading technological solutions to achieve this are offshore wind turbines. As installed capacity has been increasing rapidly and shallow water near shore sites are exhausted, projects will need to be developed further from shore and often in deeper waters, which will pose greater technical challenges and constrain efforts to reduce costs.\u0000 Current floating platform solutions such as the spar and semi-submersible rely on large amounts of ballast and complex structural designs with active stabilisation systems for stability of the floating offshore wind turbine platform (FOWT).\u0000 The primary focus of this study is to present a design concept and mooring arrangement for an alternative floating platform solution that places emphasis on the mooring system to achieve stability for a FOWT. The tension leg buoy (TLB) is designed to support future 10MW offshore wind turbine generators.\u0000 This paper presents the numerical methodology used for a coupled hydro-elastic analysis of the floater and mooring system under combined wind, wave and current effects.\u0000 A concept TLB design is presented and its platform motion and mooring line tension characteristics are analysed for a three-hour time domain simulation representing operating and survival conditions in the northern North Sea with water depths of 110 metres. The importance of wave drift forces and the other non-linear excitation forces in the concept design stage are evaluated by comparing the motion and tension responses of three different numerical simulation cases with increasing numerical complexity.\u0000 The preliminary TLB system design demonstrated satisfactory motion response for the operation of a FOWT and survival in a 100-year storm condition. The results show that accounting for second-order effect is vital in terms of having a clear understanding of the full behaviour of the system and the detailed response characteristics in operational and survival conditions. Extreme loads are significantly reduced when accounting for the second-order effects. This can be a key aspect to not overdesign the system and consequently achieve significant cost savings.","PeriodicalId":306681,"journal":{"name":"Volume 10: Ocean Renewable Energy","volume":"50 199 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125949961","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 recent times, drag-based vertical-axis wind turbine rotors have gained increasing interests in offshore applications because of their performance potential and reliability. Their advantages like simplicity, easier manufacture and lower maintenance cost have attracted the researcher’s attention toward improving their design further. However, this type of rotor is still suffering from lower efficiency than the lift-based Darrius and the horizontal-axis wind turbine rotors. A recently developed elliptical-bladed Savonius rotor has shown its potential to harvest wind energy more efficiently. However, the geometric parameters of this rotor such as aspect ratio, overlap ratio, number of blades, shaft and end plates, the aerodynamic parameters such as Reynolds number, lift and drag coefficients are needed to be optimized for further improvement of its performance. In the present investigation, the wind tunnel tests have been conducted to analyze the effect of shaft and end-plates of a newly developed elliptical-bladed vertical-axis Savonius wind turbine rotor. Experiments have been conducted over a range of tip speed ratios to find the torque and power coefficients of a two-bladed rotor system for two individual cases viz., the rotor with a shaft and the rotor with end-plates. In order to have a direct comparison, the experimental data are also obtained for the same rotor without the shaft and without the end-plates. The wind tunnel tests have demonstrated an improvement of power coefficient by 26.31% for the rotor with the end plates.
{"title":"Analyzing the Effect of Shaft and End-Plates of a Newly Developed Elliptical-Bladed Savonius Rotor From Wind Tunnel Tests","authors":"N. Alom, Nitish Kumar, U. Saha","doi":"10.1115/omae2019-95570","DOIUrl":"https://doi.org/10.1115/omae2019-95570","url":null,"abstract":"\u0000 In recent times, drag-based vertical-axis wind turbine rotors have gained increasing interests in offshore applications because of their performance potential and reliability. Their advantages like simplicity, easier manufacture and lower maintenance cost have attracted the researcher’s attention toward improving their design further. However, this type of rotor is still suffering from lower efficiency than the lift-based Darrius and the horizontal-axis wind turbine rotors. A recently developed elliptical-bladed Savonius rotor has shown its potential to harvest wind energy more efficiently. However, the geometric parameters of this rotor such as aspect ratio, overlap ratio, number of blades, shaft and end plates, the aerodynamic parameters such as Reynolds number, lift and drag coefficients are needed to be optimized for further improvement of its performance. In the present investigation, the wind tunnel tests have been conducted to analyze the effect of shaft and end-plates of a newly developed elliptical-bladed vertical-axis Savonius wind turbine rotor. Experiments have been conducted over a range of tip speed ratios to find the torque and power coefficients of a two-bladed rotor system for two individual cases viz., the rotor with a shaft and the rotor with end-plates. In order to have a direct comparison, the experimental data are also obtained for the same rotor without the shaft and without the end-plates. The wind tunnel tests have demonstrated an improvement of power coefficient by 26.31% for the rotor with the end plates.","PeriodicalId":306681,"journal":{"name":"Volume 10: Ocean Renewable Energy","volume":"68 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129322734","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}
T. Ghisu, F. Cambuli, P. Puddu, I. Virdis, Mario Carta, F. Licheri
The hysteretic behavior of OWC-installed Wells turbines has been known for decades. The common explanation invokes the presence of unsteady aerodynamics due to the continuously varying incidence of the flow on the turbine blades. This phenomenon is neither new nor unique to Wells turbines, as an aerodynamic hysteresis is present in rapidly oscillating airfoils and wings, as well as in different types of turbomachinery, such as wind turbines and helicopter rotors, which share significant similarities with a Wells turbine. An important difference is the non-dimensional frequency: the hysteresis appears in oscillating airfoils only at frequencies orders of magnitude larger than the ones Wells turbines operate at. This work contains a reexamination of the phenomenon, using both CFD and a lumped parameter model, and shows how the aerodynamic hysteresis in Wells turbines is negligible, and how the often measured differences in performance between acceleration and deceleration are caused by the capacitive behavior of the OWC system.
{"title":"A Critical Examination of the Hysteresis in Wells Turbines Using CFD and Lumped Parameter Models","authors":"T. Ghisu, F. Cambuli, P. Puddu, I. Virdis, Mario Carta, F. Licheri","doi":"10.1115/omae2019-96518","DOIUrl":"https://doi.org/10.1115/omae2019-96518","url":null,"abstract":"\u0000 The hysteretic behavior of OWC-installed Wells turbines has been known for decades. The common explanation invokes the presence of unsteady aerodynamics due to the continuously varying incidence of the flow on the turbine blades. This phenomenon is neither new nor unique to Wells turbines, as an aerodynamic hysteresis is present in rapidly oscillating airfoils and wings, as well as in different types of turbomachinery, such as wind turbines and helicopter rotors, which share significant similarities with a Wells turbine. An important difference is the non-dimensional frequency: the hysteresis appears in oscillating airfoils only at frequencies orders of magnitude larger than the ones Wells turbines operate at. This work contains a reexamination of the phenomenon, using both CFD and a lumped parameter model, and shows how the aerodynamic hysteresis in Wells turbines is negligible, and how the often measured differences in performance between acceleration and deceleration are caused by the capacitive behavior of the OWC system.","PeriodicalId":306681,"journal":{"name":"Volume 10: Ocean Renewable Energy","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128620208","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. Romolo, J. Henriques, L. Gato, G. Malara, V. Laface, R. Gomes, J. Portillo, A. Falcão, F. Arena
The REWEC3 (Resonant Wave Energy Converter) is a fixed oscillating water column (OWC) wave energy converter (WEC) incorporated in upright breakwaters. The device is composed by a chamber containing a water column in its lower part and an air pocket in its upper part. The air pocket is connected to the atmosphere via a duct hosting a self-rectifying air turbine. In addition, a REWEC3 includes a vertical U-shaped duct for connecting the water column to the open sea (for this reason it is known also as U-OWC). The working principle of the system is quite simple: by the action of the incident waves, the water inside the U-shaped duct is subject to a reciprocating motion, which induces alternately a compression and an expansion of the air pocket. The pressure difference between the air pocket and the atmosphere is used to drive an air turbine coupled to an off-the-shelf electrical generator connected to the grid. The main feature of the REWEC3 is the possibility of tuning the natural period of the water column in order to match a desired wave period through the size of the U-duct. The REWEC3 technology has been theoretically developed by Boccotti, later tested at the natural basin of the Natural Ocean Engineering Laboratory (NOEL, Italy), and finally proved at full scale with REWEC3 prototype built in the Port of Civitavecchia (Rome, Italy). The objective of this paper is to select and optimize a turbine/generator set of a U-shaped OWC installed in breakwaters located in the Mediterranean Sea, such as the Port of Civitavecchia, where the first prototype of REWEC3 has been realized, or the Port of Salerno or Marina delle Grazie of Roccella (Italy). The computations were performed using a time domain model based on the unsteady Bernoulli equation. Based on the time-domain model of the power plant, the following data is computed for the turbines: i) the ideal turbine diameter; ii) the generator feedback control law aiming to maximize the turbine power output for turbine coupled to the REWEC3 device for Mediterranean applications.
REWEC3(谐振波能转换器)是一种固定振荡水柱(OWC)波能转换器(WEC)。该装置由在其下部含有水柱和在其上部含有气穴的腔室组成。空气袋是通过管道连接到大气承载一个自整流空气涡轮机。此外，REWEC3还包括一个垂直的u形管道，用于连接水柱和公海(因此它也被称为U-OWC)。该系统的工作原理很简单:在入射波的作用下，u形管道内的水受到往复运动的影响，从而交替引起气穴的压缩和膨胀。空气袋和大气之间的压力差被用来驱动空气涡轮机，该涡轮机与连接到电网的现成发电机相连。REWEC3的主要特点是可以调整水柱的自然周期，以便通过u型管道的大小匹配所需的波周期。REWEC3技术由Boccotti在理论上开发，随后在自然海洋工程实验室(NOEL, Italy)的自然盆地进行了测试，最后在奇维塔韦基亚港(Port of Civitavecchia, Italy)建造的REWEC3原型进行了全尺寸验证。本文的目标是选择和优化安装在地中海防波堤上的u型OWC的涡轮/发电机组，例如已实现REWEC3首个原型的奇维塔韦基亚港，或萨莱诺港或罗塞拉的Marina delle Grazie港(意大利)。采用基于非定常伯努利方程的时域模型进行计算。根据电厂的时域模型，计算汽轮机的如下数据:1)理想汽轮机直径;ii)发电机反馈控制律，旨在最大化涡轮功率输出，用于地中海应用的涡轮耦合到REWEC3设备。
{"title":"Power Take-Off Selection for a U-Shaped OWC Wave Energy Converter","authors":"A. Romolo, J. Henriques, L. Gato, G. Malara, V. Laface, R. Gomes, J. Portillo, A. Falcão, F. Arena","doi":"10.1115/omae2019-96368","DOIUrl":"https://doi.org/10.1115/omae2019-96368","url":null,"abstract":"\u0000 The REWEC3 (Resonant Wave Energy Converter) is a fixed oscillating water column (OWC) wave energy converter (WEC) incorporated in upright breakwaters. The device is composed by a chamber containing a water column in its lower part and an air pocket in its upper part. The air pocket is connected to the atmosphere via a duct hosting a self-rectifying air turbine. In addition, a REWEC3 includes a vertical U-shaped duct for connecting the water column to the open sea (for this reason it is known also as U-OWC). The working principle of the system is quite simple: by the action of the incident waves, the water inside the U-shaped duct is subject to a reciprocating motion, which induces alternately a compression and an expansion of the air pocket. The pressure difference between the air pocket and the atmosphere is used to drive an air turbine coupled to an off-the-shelf electrical generator connected to the grid.\u0000 The main feature of the REWEC3 is the possibility of tuning the natural period of the water column in order to match a desired wave period through the size of the U-duct. The REWEC3 technology has been theoretically developed by Boccotti, later tested at the natural basin of the Natural Ocean Engineering Laboratory (NOEL, Italy), and finally proved at full scale with REWEC3 prototype built in the Port of Civitavecchia (Rome, Italy).\u0000 The objective of this paper is to select and optimize a turbine/generator set of a U-shaped OWC installed in breakwaters located in the Mediterranean Sea, such as the Port of Civitavecchia, where the first prototype of REWEC3 has been realized, or the Port of Salerno or Marina delle Grazie of Roccella (Italy). The computations were performed using a time domain model based on the unsteady Bernoulli equation.\u0000 Based on the time-domain model of the power plant, the following data is computed for the turbines: i) the ideal turbine diameter; ii) the generator feedback control law aiming to maximize the turbine power output for turbine coupled to the REWEC3 device for Mediterranean applications.","PeriodicalId":306681,"journal":{"name":"Volume 10: Ocean Renewable Energy","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116840849","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}
Xiuqing Xing, C. Kang, George Xu, J. Lou, K. Takagi, J. Sinclair
A three dimensional Computational Fluid Dynamics (CFD) model solving Reynolds-averaged Navier-Stokes (RANS) equations with k-ε turbulence model has been developed based on OpenFoam to investigate a tidal turbine performance. The CFD model is validated by comparing the simulation results with the performance characteristic data. Simulation results match the measured data with discrepancies less than 5.4%. The well validated model is then adopted to predict the turbine performance with a current heading angle of 30 degree. The simulated turbine power coefficient and flow field details from OpenFoam are compared with those obtained from commercial software ANSYS FLUENT for verification. The two simulated results match each other with a difference of only 3%. Simulated results indicate that the turbine power output drops significantly when the tidal turbine operates with a current heading angle of 30 degree. The performance loss due to a misalignment between the current and the turbine axis is analyzed with the aim to identify main causes and provide recommendations to tidal turbine operation.
{"title":"Numerical Analysis of Tidal Turbine Performance for Floating Platform","authors":"Xiuqing Xing, C. Kang, George Xu, J. Lou, K. Takagi, J. Sinclair","doi":"10.1115/omae2019-95884","DOIUrl":"https://doi.org/10.1115/omae2019-95884","url":null,"abstract":"\u0000 A three dimensional Computational Fluid Dynamics (CFD) model solving Reynolds-averaged Navier-Stokes (RANS) equations with k-ε turbulence model has been developed based on OpenFoam to investigate a tidal turbine performance. The CFD model is validated by comparing the simulation results with the performance characteristic data. Simulation results match the measured data with discrepancies less than 5.4%. The well validated model is then adopted to predict the turbine performance with a current heading angle of 30 degree. The simulated turbine power coefficient and flow field details from OpenFoam are compared with those obtained from commercial software ANSYS FLUENT for verification. The two simulated results match each other with a difference of only 3%. Simulated results indicate that the turbine power output drops significantly when the tidal turbine operates with a current heading angle of 30 degree. The performance loss due to a misalignment between the current and the turbine axis is analyzed with the aim to identify main causes and provide recommendations to tidal turbine operation.","PeriodicalId":306681,"journal":{"name":"Volume 10: Ocean Renewable Energy","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115453471","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}
Jiang Yichen, Peidong Zhao, L. Zou, Guiyong Zhang, Z. Zong
A novel design of offshore twin counter-rotating vertical axis wind turbines (VAWTs) with deflector is proposed in this paper. We investigate the performance of the twin VAWTs by the two-dimensional computational fluid dynamic method with the Spalart-Allmaras turbulence model. Then, the performances of twin VAWTs with three kinds of deflectors are compared. The results show that installing the front deflector leads to significant improved aerodynamic performance. To better understand the simulation results, we introduce a simple and effective method to obtain the blade’s angle of attack. The mechanism of enhanced performance by deflector is pointed out, based on the information of the blade’s local angle of attack and flow field. Finally, a guideline on the design of deflector for the twin vertical axis wind turbines is provided.
{"title":"The Aerodynamic Performance of Offshore Twin Vertical Axis Wind Turbines With Deflector","authors":"Jiang Yichen, Peidong Zhao, L. Zou, Guiyong Zhang, Z. Zong","doi":"10.1115/omae2019-95104","DOIUrl":"https://doi.org/10.1115/omae2019-95104","url":null,"abstract":"\u0000 A novel design of offshore twin counter-rotating vertical axis wind turbines (VAWTs) with deflector is proposed in this paper. We investigate the performance of the twin VAWTs by the two-dimensional computational fluid dynamic method with the Spalart-Allmaras turbulence model. Then, the performances of twin VAWTs with three kinds of deflectors are compared. The results show that installing the front deflector leads to significant improved aerodynamic performance. To better understand the simulation results, we introduce a simple and effective method to obtain the blade’s angle of attack. The mechanism of enhanced performance by deflector is pointed out, based on the information of the blade’s local angle of attack and flow field. Finally, a guideline on the design of deflector for the twin vertical axis wind turbines is provided.","PeriodicalId":306681,"journal":{"name":"Volume 10: Ocean Renewable Energy","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125233631","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}
Zheng Chen, Zeng Weijian, Ming Tan, Dahai Zhang, Yulin Si
Recent years have seen rapid development in offshore wind technology. Particularly, floating offshore wind turbines possess great potential in deep water coastal places around the world, though they are now still in the demonstration phase. At the same time, the unused wave energy is also abundant at the sites of offshore wind farms, especially those in deep sea regions. Collecting wave energy in offshore wind farms might benefit both total energy production and reduce maintenance cost. Therefore, integrating offshore wind turbine with wave energy conversion devices could be a good idea to achieve higher efficiency and lower cost. In this paper, we report a combined wind and wave energy power generation concept called WindOWC, which constits of a 5MW wind turbine and three oscillating-water-column (OWC) wave energy converters (WECs). The wind turbine is mounted on a semi-submersible floating platform, which is similar to OC4-semibsubmersible, and the OWCs are located in its three offset columns. In this design, the wind turbine and WECs share the same supporting platform and the power transmission system, thus is expected to reduce the cost of energy. Also, it is possible the OWCs may improve the platform dynamic performance by providing positive damping through controlling the air turbine rotational speed. In this work, we describe the geometry properties of the proposed WindOWC concept and conduct preliminary hydrodynamic analysis using potential flow theory. The ANSYS AQWA is used to obtain the system dynamic responses in frequency and time domain, respectively. The OWC dynamics and expected positive damping from them will be investigated in the future.
{"title":"A Hybrid Power Generation Platform Combining Floating Wind Turbine and Oscillating Water Column Wave Energy Converters","authors":"Zheng Chen, Zeng Weijian, Ming Tan, Dahai Zhang, Yulin Si","doi":"10.1115/omae2019-95968","DOIUrl":"https://doi.org/10.1115/omae2019-95968","url":null,"abstract":"\u0000 Recent years have seen rapid development in offshore wind technology. Particularly, floating offshore wind turbines possess great potential in deep water coastal places around the world, though they are now still in the demonstration phase. At the same time, the unused wave energy is also abundant at the sites of offshore wind farms, especially those in deep sea regions. Collecting wave energy in offshore wind farms might benefit both total energy production and reduce maintenance cost. Therefore, integrating offshore wind turbine with wave energy conversion devices could be a good idea to achieve higher efficiency and lower cost.\u0000 In this paper, we report a combined wind and wave energy power generation concept called WindOWC, which constits of a 5MW wind turbine and three oscillating-water-column (OWC) wave energy converters (WECs). The wind turbine is mounted on a semi-submersible floating platform, which is similar to OC4-semibsubmersible, and the OWCs are located in its three offset columns. In this design, the wind turbine and WECs share the same supporting platform and the power transmission system, thus is expected to reduce the cost of energy. Also, it is possible the OWCs may improve the platform dynamic performance by providing positive damping through controlling the air turbine rotational speed. In this work, we describe the geometry properties of the proposed WindOWC concept and conduct preliminary hydrodynamic analysis using potential flow theory. The ANSYS AQWA is used to obtain the system dynamic responses in frequency and time domain, respectively. The OWC dynamics and expected positive damping from them will be investigated in the future.","PeriodicalId":306681,"journal":{"name":"Volume 10: Ocean Renewable Energy","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131538525","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}
Sewan Park, Kyong-Hwan Kim, B. Nam, Jeong-Seok Kim, K. Hong
In the present study, the primary energy conversion performance of an oscillating water column (OWC) was evaluated through experimental tests and numerical simulations. The experimental tests were performed at an ocean basin located in Korea Research Institute of Ships and Ocean Engineering (KRISO), Korea. A 1/4 scaled OWC chamber model with an orifice to account for the turbine effect was set up at the 3-dimensional basin, and regular wave tests were performed at various incident wave periods. The water surface level inside the chamber, the differential pressure between before and after the orifice, and the airflow speed through the orifice were measured. Computational fluid dynamics (CFD) analysis was performed using the Star-CCM+ commercial software to analyze the performance of the OWC for the same model that was used in the experiment. Detailed flow fields were discussed based on the CFD results, and the numerical and experimental results were compared. The validation results showed good agreement.
{"title":"Experimental and Numerical Analysis of Performance of Oscillating Water Column Wave Energy Converter Applicable to Breakwaters","authors":"Sewan Park, Kyong-Hwan Kim, B. Nam, Jeong-Seok Kim, K. Hong","doi":"10.1115/omae2019-96500","DOIUrl":"https://doi.org/10.1115/omae2019-96500","url":null,"abstract":"\u0000 In the present study, the primary energy conversion performance of an oscillating water column (OWC) was evaluated through experimental tests and numerical simulations. The experimental tests were performed at an ocean basin located in Korea Research Institute of Ships and Ocean Engineering (KRISO), Korea. A 1/4 scaled OWC chamber model with an orifice to account for the turbine effect was set up at the 3-dimensional basin, and regular wave tests were performed at various incident wave periods. The water surface level inside the chamber, the differential pressure between before and after the orifice, and the airflow speed through the orifice were measured. Computational fluid dynamics (CFD) analysis was performed using the Star-CCM+ commercial software to analyze the performance of the OWC for the same model that was used in the experiment. Detailed flow fields were discussed based on the CFD results, and the numerical and experimental results were compared. The validation results showed good agreement.","PeriodicalId":306681,"journal":{"name":"Volume 10: Ocean Renewable Energy","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133097537","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 safety assessment for wave energy converters (WECs) in model scale is necessary before a demonstration test. WECs have various control conditions such as a maintenance and power generation mode etc. Although the safety assessment is required to carry out while considering the control conditions, the motion and load characteristics of the moored WEC to which applies various control conditions remains unclear. This study investigated the motion and load characteristics of the WEC including a mooring system when each control conditions was used. In experiments, the motion and load characteristics of the WEC without control were revealed. In the simulation, the motion and load characteristics were compared between two control methods which are the resistive loading control (RLC) and the approximate complex-conjugate control with considering the copper loss (ACL). The control methods have little effects on the surging, pitching and bending moment of the WEC. Mooring tension increased with increasing wave period when the RLC was used. When the ACL was applied, mooring tension reached the peak value near the natural period and decreased with increasing the wave period. The difference in the trends leads to that the control method maximizing mooring tension is not necessarily the same in each wave period. The select of the operating condition based on the wave period is required when the mooring tension of the WEC is assessed in the model-scale test stage.
{"title":"Study on a Wave Energy Converter With Tension Leg Mooring Under Optimal Control","authors":"Jun Umeda, Tomoki Taniguchi, T. Fujiwara","doi":"10.1115/omae2019-95650","DOIUrl":"https://doi.org/10.1115/omae2019-95650","url":null,"abstract":"\u0000 A safety assessment for wave energy converters (WECs) in model scale is necessary before a demonstration test. WECs have various control conditions such as a maintenance and power generation mode etc. Although the safety assessment is required to carry out while considering the control conditions, the motion and load characteristics of the moored WEC to which applies various control conditions remains unclear. This study investigated the motion and load characteristics of the WEC including a mooring system when each control conditions was used. In experiments, the motion and load characteristics of the WEC without control were revealed. In the simulation, the motion and load characteristics were compared between two control methods which are the resistive loading control (RLC) and the approximate complex-conjugate control with considering the copper loss (ACL). The control methods have little effects on the surging, pitching and bending moment of the WEC. Mooring tension increased with increasing wave period when the RLC was used. When the ACL was applied, mooring tension reached the peak value near the natural period and decreased with increasing the wave period. The difference in the trends leads to that the control method maximizing mooring tension is not necessarily the same in each wave period. The select of the operating condition based on the wave period is required when the mooring tension of the WEC is assessed in the model-scale test stage.","PeriodicalId":306681,"journal":{"name":"Volume 10: Ocean Renewable Energy","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130949751","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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