The Experts below are selected from a list of 28512 Experts worldwide ranked by ideXlab platform
M L G Oldfield - One of the best experts on this subject based on the ideXlab platform.
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experimental measurements of the Hydrodynamic Performance and structural loading of the transverse horizontal axis water turbine part 1
Renewable Energy, 2013Co-Authors: Ross A Mcadam, Guy T. Houlsby, M L G OldfieldAbstract:This paper is the first of three, which outline the procedures and results for a set of experiments carried out on various configurations of the Transverse Horizontal Axis Water Turbine (THAWT), which is a horizontally orientated variant of the Darrieus cross-flow turbine. Tests were conducted in the combined wind, wave and current tank at Newcastle University on a 0.5 m diameter rotor, while the flow depth and velocity were varied over a range of realistic Froude numbers for tidal streams. Various configurations of the device were tested to assess the merits of varied blade pitch, rotor solidity, blockage ratio and truss oriented blades. Experiments were carried out using a speed controlled motor/generator, allowing quasi-steady results to be taken over a range of tip speed ratios. Measurements of power, thrust, blade loading and free surface deformation provide extensive data for future validation of numerical codes and demonstrate the ability of the device to exceed the Lanchester-Betz limit for kinetic efficiency by using high blockage. This paper covers the experimental procedures and results for the Hydrodynamic Performance for the parallel bladed variant of the THAWT device. The second paper covers the Hydrodynamic loading of the parallel bladed rotor and the third covers both Hydrodynamic Performance and loading of the truss configured THAWT device.
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experimental measurements of the Hydrodynamic Performance and structural loading of the transverse horizontal axis water turbine part 3
Renewable Energy, 2013Co-Authors: Ross A Mcadam, Guy T. Houlsby, M L G OldfieldAbstract:Abstract This paper is the third of three, which describe the procedures and results for a set of experiments on various configurations of the Transverse Horizontal Axis Water Turbine (THAWT), which is a horizontally orientated variant of the Darrieus cross-flow turbine. Tests were conducted in the combined wind, wave and current tank at Newcastle University on a 0.5 m diameter rotor, while the flow depth and velocity were varied over a range of realistic Froude numbers for tidal streams. Various configurations of the device were tested to assess the merits of varied blade pitch, rotor solidity, blockage ratio and truss oriented blades. Experiments were carried out using a speed-controlled motor/generator, allowing quasi-steady results to be taken over a range of tip speed ratios. Measurements of power, thrust, blade loading and free surface deformation provide extensive data for future validation of numerical codes and demonstrate the ability of the device to exceed the Lanchester–Betz limit for kinetic efficiency by using high blockage. This paper covers the instrumentation, Hydrodynamic Performance and loading of the truss bladed variant of the THAWT device. The first paper covers the experimental setup and Hydrodynamic Performance of the parallel bladed rotor and the second paper covers the instrumentation and Hydrodynamic loading of the parallel bladed rotor.
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experimental measurements of the Hydrodynamic Performance and structural loading of the transverse horizontal axis water turbine part 2
Renewable Energy, 2013Co-Authors: Ross A Mcadam, Guy T. Houlsby, M L G OldfieldAbstract:Abstract This paper is the second of three, which outline the procedures and results for a set of experiments on various configurations of the Transverse Horizontal Axis Water Turbine (THAWT), which is a horizontally orientated variant of the Darrieus cross-flow turbine. Tests were conducted in the combined wind, wave and current tank at Newcastle University on a 0.5 m diameter rotor, while the flow depth and velocity were varied over a range of realistic Froude numbers for tidal streams. Various configurations of the device were tested to assess the merits of varied blade pitch, rotor solidity, blockage ratio and truss oriented blades. Experiments were carried out using a speed controlled motor/generator, allowing quasi-steady results to be taken over a range of tip speed ratios. Measurements of power, thrust, blade loading and free surface deformation provide extensive data for future validation of numerical codes and demonstrate the ability of the device to exceed the Lanchester–Betz limit for kinetic efficiency, by exploiting high blockage. This second paper covers the instrumentation and analysis for the structural loading for the parallel bladed variant of the THAWT device. The first paper covers the experimental setup and Hydrodynamic Performance of the parallel bladed rotor, and the third paper covers both Performance and loading of the truss configured THAWT device.
Binzhen Zhou - One of the best experts on this subject based on the ideXlab platform.
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Hydrodynamic Performance of a dual floater hybrid system combining a floating breakwater and an oscillating buoy type wave energy converter
Applied Energy, 2020Co-Authors: Hengming Zhang, Binzhen Zhou, Christopher R Vogel, Richard H J Willden, Jun Zang, Jing GengAbstract:The high cost of power generation impedes commercial-scale wave power operations. The objective of this work is to provide a cost-sharing solution by combining wave energy extraction and coastal protection. A two-dimensional numerical wave tank was developed using Star-CCM+ Computational Fluid Dynamics software to investigate the Hydrodynamic Performance of a dual-floater hybrid system consisting of a floating breakwater and an oscillating-buoy type wave energy converter (WEC), and was compared with published experimental results. The differences between the Hydrodynamic Performance of the hybrid system, a single WEC and a single breakwater were compared. Wave resonance in the WEC-breakwater gap has a significant impact on system Performance, with the hybrid system demonstrating both better wave attenuation and wave energy extraction capabilities at low wave frequencies, i.e., wider effective frequency. Forces on the breakwater were generally reduced due to the WEC. Wave resonance in the narrow gap has an adverse effect on the energy efficiency of the hybrid system with an asymmetric WEC, while a beneficial effect with a symmetric WEC. The wave energy conversion efficiency of hybrid system can be improved by increasing the draft and width of the WEC and decreasing the distance between the WEC and the breakwater. The findings of this paper make wave energy economically competitive and commercial-scale wave power operations possible.
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Hydrodynamic Performance of a floating breakwater as an oscillating buoy type wave energy converter
Applied Energy, 2020Co-Authors: Hengming Zhang, Binzhen Zhou, Christopher R Vogel, Richard H J Willden, Jun Zang, Liang ZhangAbstract:Abstract Combined floating breakwater and wave energy converter systems have the potential to provide a cost-effective solution to offshore power supply and coastal protection. This will make wave energy economically competitive and commercial-scale wave power operations possible. This paper investigates the Hydrodynamic features of wave energy converters that meet the dual objectives of wave energy extraction and attenuation for such a combined system. A two-dimensional numerical model was established using Star-CCM+ commercial software based on viscous Computational Fluid Dynamics theory to investigate the Hydrodynamic Performance of an oscillating buoy Wave Energy Converter (WEC) type floating breakwater under regular waves. The model proposed in this paper was verified with published experimental results. The Hydrodynamics of symmetric and asymmetric floaters were investigated to demonstrate their wave attenuation and energy extraction Performance, including square bottomed, triangular bottomed (with and without a baffle plate), and the Berkley Wedge. The asymmetric floaters were found to have higher power conversion efficiency and better wave attenuation Performance, especially the Berkeley Wedge bottom device and the triangular-baffle bottom device. The triangular-baffle bottom device with a simpler geometry achieved similar wave attenuation and energy extraction Performance characteristics to that of the Berkeley Wedge device. The maximum energy conversion efficiency of the triangular-baffle bottom floater reached up to 93%, an impressive WEC device among many designs for wave energy conversion. There may be a great potential for this newly proposed triangular-baffle bottom WEC type of floater to be an ideal coastal structure for both coastal protection and wave energy extraction.
Ross A Mcadam - One of the best experts on this subject based on the ideXlab platform.
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experimental measurements of the Hydrodynamic Performance and structural loading of the transverse horizontal axis water turbine part 1
Renewable Energy, 2013Co-Authors: Ross A Mcadam, Guy T. Houlsby, M L G OldfieldAbstract:This paper is the first of three, which outline the procedures and results for a set of experiments carried out on various configurations of the Transverse Horizontal Axis Water Turbine (THAWT), which is a horizontally orientated variant of the Darrieus cross-flow turbine. Tests were conducted in the combined wind, wave and current tank at Newcastle University on a 0.5 m diameter rotor, while the flow depth and velocity were varied over a range of realistic Froude numbers for tidal streams. Various configurations of the device were tested to assess the merits of varied blade pitch, rotor solidity, blockage ratio and truss oriented blades. Experiments were carried out using a speed controlled motor/generator, allowing quasi-steady results to be taken over a range of tip speed ratios. Measurements of power, thrust, blade loading and free surface deformation provide extensive data for future validation of numerical codes and demonstrate the ability of the device to exceed the Lanchester-Betz limit for kinetic efficiency by using high blockage. This paper covers the experimental procedures and results for the Hydrodynamic Performance for the parallel bladed variant of the THAWT device. The second paper covers the Hydrodynamic loading of the parallel bladed rotor and the third covers both Hydrodynamic Performance and loading of the truss configured THAWT device.
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experimental measurements of the Hydrodynamic Performance and structural loading of the transverse horizontal axis water turbine part 3
Renewable Energy, 2013Co-Authors: Ross A Mcadam, Guy T. Houlsby, M L G OldfieldAbstract:Abstract This paper is the third of three, which describe the procedures and results for a set of experiments on various configurations of the Transverse Horizontal Axis Water Turbine (THAWT), which is a horizontally orientated variant of the Darrieus cross-flow turbine. Tests were conducted in the combined wind, wave and current tank at Newcastle University on a 0.5 m diameter rotor, while the flow depth and velocity were varied over a range of realistic Froude numbers for tidal streams. Various configurations of the device were tested to assess the merits of varied blade pitch, rotor solidity, blockage ratio and truss oriented blades. Experiments were carried out using a speed-controlled motor/generator, allowing quasi-steady results to be taken over a range of tip speed ratios. Measurements of power, thrust, blade loading and free surface deformation provide extensive data for future validation of numerical codes and demonstrate the ability of the device to exceed the Lanchester–Betz limit for kinetic efficiency by using high blockage. This paper covers the instrumentation, Hydrodynamic Performance and loading of the truss bladed variant of the THAWT device. The first paper covers the experimental setup and Hydrodynamic Performance of the parallel bladed rotor and the second paper covers the instrumentation and Hydrodynamic loading of the parallel bladed rotor.
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experimental measurements of the Hydrodynamic Performance and structural loading of the transverse horizontal axis water turbine part 2
Renewable Energy, 2013Co-Authors: Ross A Mcadam, Guy T. Houlsby, M L G OldfieldAbstract:Abstract This paper is the second of three, which outline the procedures and results for a set of experiments on various configurations of the Transverse Horizontal Axis Water Turbine (THAWT), which is a horizontally orientated variant of the Darrieus cross-flow turbine. Tests were conducted in the combined wind, wave and current tank at Newcastle University on a 0.5 m diameter rotor, while the flow depth and velocity were varied over a range of realistic Froude numbers for tidal streams. Various configurations of the device were tested to assess the merits of varied blade pitch, rotor solidity, blockage ratio and truss oriented blades. Experiments were carried out using a speed controlled motor/generator, allowing quasi-steady results to be taken over a range of tip speed ratios. Measurements of power, thrust, blade loading and free surface deformation provide extensive data for future validation of numerical codes and demonstrate the ability of the device to exceed the Lanchester–Betz limit for kinetic efficiency, by exploiting high blockage. This second paper covers the instrumentation and analysis for the structural loading for the parallel bladed variant of the THAWT device. The first paper covers the experimental setup and Hydrodynamic Performance of the parallel bladed rotor, and the third paper covers both Performance and loading of the truss configured THAWT device.
Ahmed Elhanafi - One of the best experts on this subject based on the ideXlab platform.
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Hydrodynamic Performance of single chamber and dual chamber offshore stationary oscillating water column devices using cfd
Applied Energy, 2018Co-Authors: Ahmed Elhanafi, Gregor Macfarlane, Dezhi NingAbstract:The Oscillating Water Column (OWC) is considered to be one of the most promising Wave Energy Converter (WEC) concepts in terms of practicality, survivability and efficiency. To date, most research has focussed on single–chamber devices, but it is suggested that significant increases in energy extraction can be achieved from dual–chamber devices. This paper investigates, using well–validated 2D and 3D CFD models based on the Reynolds Averaged Navier–Stokes (RANS) equations and the Volume of Fluid (VOF) method, the Hydrodynamic Performance of various dual–chamber offshore–stationary OWC–WECs and compares the results to single–chamber OWC devices. The effect of chamber lip draught, chamber length in wave propagation direction and the power take–off (PTO) damping on the capture width ratio (power extraction efficiency) of each OWC device was studied over a wide range of wave periods for a constant regular wave height. It was found that all the parameters tested were important for the design of efficient OWC devices, and the dual–chamber device provided superior results to the single–chamber device, especially over the intermediate and long wave periods where the capture width ratio could be improved by a maximum of about 140%; hence extracting significantly more energy. The effectiveness of using the dual–chamber system was more obvious when 3D effects were considered. The findings of this paper contribute towards the design and operation of practical OWC devices for efficiently utilizing ocean waves to produce electricity.
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experimental and numerical investigations on the Hydrodynamic Performance of a floating moored oscillating water column wave energy converter
Applied Energy, 2017Co-Authors: Ahmed Elhanafi, Gregor Macfarlane, Alan Fleming, Zhi LeongAbstract:This paper presents an experimental and numerical Hydrodynamic Performance assessment of a 1:50 scale model offshore floating–moored Oscillating Water Column (OWC) wave energy converter. The device is a tension–leg structure with four vertical mooring lines. The Performance of the OWC device was investigated for several design parameters including regular and irregular wave conditions of different heights and periods, power take–off (PTO) damping and mooring line pre–tension. A 3D Computational Fluid Dynamics (CFD) model using RANS–VOF approach was constructed and validated against experimental results for regular waves showing good agreement. It was found that the Hydrodynamic efficiency of the floating–moored OWC device follows the same general trend as a fully–constrained (fixed) model, but the addition of surge motion in the floating device improved the energy production efficiency over a broader bandwidth around the chamber resonance. Increasing the incoming wave height resulted in a higher efficiency for low–frequency waves, but noticeable reductions in the efficiency were observed in the intermediate– and high– frequency zones. The effectiveness of utilizing offshore OWC devices in deep–water was demonstrated by increasing the extracted energy by a maximum of 7.7 times and 5.7 times when regular and irregular wave heights were doubled, respectively. Decreasing the mooring line pre–tension slightly increases the energy extraction efficiency in the intermediate–frequency zone.
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underwater geometrical impact on the Hydrodynamic Performance of an offshore oscillating water column wave energy converter
Renewable Energy, 2017Co-Authors: Ahmed Elhanafi, Gregor Macfarlane, Alan Fleming, Zhi LeongAbstract:Understanding the Hydrodynamic Performance of offshore Oscillating Water Column (OWC) devices is essential for assisting the development and optimization processes. The chamber underwater geometry is one of the paramount design aspects that strongly affect the wave–OWC interactions. This paper utilizes a well–validated two–dimensional, fully nonlinear Computational Fluid Dynamics (CFD) model to investigate the impact the underwater front and rear lips have on the Hydrodynamic Performance of an offshore stationary OWC. An extensive campaign of numerical simulations is performed to discover the relevance of the front and rear lip submergence and thickness to OWC Performance. The key finding is that the overall Hydrodynamic efficiency can be significantly improved over a broad frequency bandwidth by selecting suitable values for both the submergence ratio of asymmetric lips and the lip thickness. The device that is capable of absorbing a large amount of the incoming wave energy provides the maximum power extraction efficiency and the maximum energy losses. The optimal combination achieved a peak efficiency exceeding 0.79, which represents a massive enhancement over more simplistic, but commonly accepted, geometries that returned peak efficiencies of approximately 0.30.
Dezhi Ning - One of the best experts on this subject based on the ideXlab platform.
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experimental investigation on the Hydrodynamic Performance of a cylindrical dual chamber oscillating water column device
Applied Energy, 2020Co-Authors: Dezhi Ning, Yu Zhou, Robert Mayon, Lars JohanningAbstract:Abstract The Hydrodynamic Performance of a stationary cylindrical dual-chamber Oscillating Water Column (OWC) wave energy device was experimentally studied to assess conversion efficiency in comparison with a single-chamber OWC. The contribution of the present work is to guide the design and optimization of the dual-chamber OWC device for efficiently capturing offshore wave energy. The effects of various parameters including wave steepness, the opening ratio, the inner- and outer-chamber drafts on the Hydrodynamic efficiency of the proposed OWC device were considered. It was found that the Hydrodynamic efficiency of the dual-chamber OWC device increases by comparison with the single-chamber one. A coupled resonant effect between the inner- and outer-chambers was observed for the dual-chamber OWC, which leads to the difference between the resonant frequencies and broadens the effective frequency bandwidth. The ratio of the orifice opening area to the area of the chamber columns has a significant influence on the Hydrodynamic efficiency. The optimal opening ratio is founded to be between 1.5% and 2.0% in the present study. It was also observed that the Hydrodynamic efficiency decreases with the increase of wave steepness and increases with the decrease of the outer-chamber draft.
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Hydrodynamic Performance of single chamber and dual chamber offshore stationary oscillating water column devices using cfd
Applied Energy, 2018Co-Authors: Ahmed Elhanafi, Gregor Macfarlane, Dezhi NingAbstract:The Oscillating Water Column (OWC) is considered to be one of the most promising Wave Energy Converter (WEC) concepts in terms of practicality, survivability and efficiency. To date, most research has focussed on single–chamber devices, but it is suggested that significant increases in energy extraction can be achieved from dual–chamber devices. This paper investigates, using well–validated 2D and 3D CFD models based on the Reynolds Averaged Navier–Stokes (RANS) equations and the Volume of Fluid (VOF) method, the Hydrodynamic Performance of various dual–chamber offshore–stationary OWC–WECs and compares the results to single–chamber OWC devices. The effect of chamber lip draught, chamber length in wave propagation direction and the power take–off (PTO) damping on the capture width ratio (power extraction efficiency) of each OWC device was studied over a wide range of wave periods for a constant regular wave height. It was found that all the parameters tested were important for the design of efficient OWC devices, and the dual–chamber device provided superior results to the single–chamber device, especially over the intermediate and long wave periods where the capture width ratio could be improved by a maximum of about 140%; hence extracting significantly more energy. The effectiveness of using the dual–chamber system was more obvious when 3D effects were considered. The findings of this paper contribute towards the design and operation of practical OWC devices for efficiently utilizing ocean waves to produce electricity.
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nonlinear and viscous effects on the Hydrodynamic Performance of a fixed owc wave energy converter
Coastal Engineering, 2018Co-Authors: Rongquan Wang, Dezhi Ning, Chongwei Zhang, Qingping Zou, Zhen LiuAbstract:Abstract The Hydrodynamic Performance of a fixed Oscillating Water Column (OWC) device is experimentally and numerically investigated. Based on the time-domain higher-order boundary element method (HOBEM), by introducing an artificial viscosity term in the dynamic free surface boundary condition, a fully nonlinear numerical wave model is used to simulate the Hydrodynamic Performance of an OWC device. A set of comprehensive experiments for regular waves is carried out to validate the numerical results as well as to investigate the nonlinear effects on the Hydrodynamic Performance of OWC. The mechanism of the nonlinear phenomenon is investigated based on the analysis of the experimental and numerical results. The influence of the wave nonlinearity and the viscosity on the Hydrodynamic efficiency is quantified by comparing the linear and nonlinear numerical results. It was found that the Hydrodynamic efficiency increases with the nonlinearity and viscosity when the incident wave amplitude is small. When the incident wave amplitude is large, the Hydrodynamic efficiency is reduced by the weakened transmission of the second-order harmonic wave component due to the strong wave nonlinearity. However, when the wave amplitude is between these two regimes, the wave is weakly nonlinear, the efficiency decreases with the wave amplitude due to the combined effect of the nonlinearity and viscosity.
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analytical investigation of Hydrodynamic Performance of a dual pontoon wec type breakwater
Applied Ocean Research, 2017Co-Authors: Dezhi Ning, Xuanlie Zhao, Ming Zhao, Martyn Hann, Haigui KangAbstract:publisher: Elsevier articletitle: Analytical investigation of Hydrodynamic Performance of a dual pontoon WEC-type breakwater journaltitle: Applied Ocean Research articlelink: http://dx.doi.org/10.1016/j.apor.2017.03.012 content_type: article copyright: © 2017 Elsevier Ltd. All rights reserved.
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Hydrodynamic Performance of a pile restrained wec type floating breakwater an experimental study
Renewable Energy, 2016Co-Authors: Dezhi Ning, Xuanlie Zhao, Malin Goteman, Haigui KangAbstract:In this paper, a system which integrates an oscillating buoy type wave energy converter with a vertical pile-restrained floating breakwater is introduced. A preliminary experimental study on the Hydrodynamic Performance of the system is carried out in a wave flume under the action of regular waves. A current controller-magnetic powder brake system is used to simulate the power generation system. The design is verified against published results. The power-take off damping characteristics are investigated, and the current controller-magnetic powder brake system can simulate the (approximate) Coulomb damping force very well. The effects of various parameters, including wave period and wave height, dimensions of the system and excitation current, on the Hydrodynamic Performance are investigated. Results indicate that the power take-off damping force, draft and relative width between the floating breakwater and the wavelength have a significant influence on the Hydrodynamic Performance of the system. A range can be observed for which the capture width ratio of the system can achieve approximately 24% while transmission coefficient was kept lower than 0.50 with the proper adjustment of power take-off damping force, and the floating breakwater performs in an effective manner. The new concept provides a promising way to utilize wave energy cost-effectively.
