The Experts below are selected from a list of 1524 Experts worldwide ranked by ideXlab platform
A. Thakker - One of the best experts on this subject based on the ideXlab platform.
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design charts for Impulse Turbine wave energy extraction using experimental data
Renewable Energy, 2009Co-Authors: A. Thakker, J. Jarvis, A. SahedAbstract:This study presents newly developed charts to aid in early design of Impulse Turbine for wave energy extraction. These charts, based on the available experimental data, represent a simple approach to the performance evaluation of the Turbine. The novel approach is applied in a case study that considers the optimum diameter design selection of next-generation Impulse Turbine power take-off. This allowed the selection of the correct Impulse Turbine sizing for a required rated power. The result is consistent for such an application, where the optimum rotor diameter would be 1.6 m for a maximum rated power of 400 kW.
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3dcad conceptual design of the next generation Impulse Turbine using the pugh decision matrix
Materials & Design, 2009Co-Authors: A. Thakker, J. Jarvis, M Buggy, A. SahedAbstract:Abstract Achieving the economic and viability of power generation from wave energy requires design and development of new and improved machinery. This paper displays the design of an improved Impulse Turbine using a systematic method, which combines two powerful design tools, i.e. Pugh concept analysis and 3DCAD environment. Using this approach allows the user to combine the strength of Pugh’s method and the design space, allowing the concept selection process to be streamlined. This brings new concept in the mechanical design field, which is inline with the technological trends prevalent in the industry. The capabilities of the proposed approach is applied in a case study that considers Impulse Turbine wave energy extraction optimum design. The latter was arrived at by combining and/or refining the alternatives as the process develops. Furthermore, the optimum design has been tested for structural performance using structural analysis integrated within the 3DCAD environment. The results show a moderate design stress which would relax the manufacturing technique, and yet with a good safety factor.
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Quasi-Steady Analytical Model Benchmark of an Impulse Turbine for Wave Energy Extraction
International Journal of Rotating Machinery, 2008Co-Authors: A. Thakker, J. Jarvis, A. SahedAbstract:This work presents a mean line analysis for the prediction of the performance and aerodynamic loss of axial flow Impulse Turbine wave energy extraction, which can be easily incorporated into the Turbine design program. The model is based on the momentum principle and the well-known Euler Turbine equation. Predictions of torque, pressure drop, and Turbine efficiency showed favorable agreement with experimental results. The variation of the flow incidence and exit angles with the flow coefficient has been reported for the first time in the field of wave energy extraction. Furthermore, an optimum range of upstream guide vanes setting up angle was determined, which optimized the Impulse Turbine performance prediction under movable guide vanes working condition.
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A novel approach to materials selection strategy case study: Wave energy extraction Impulse Turbine blade
Materials & Design, 2008Co-Authors: A. Thakker, J. Jarvis, M Buggy, A. SahedAbstract:Abstract This paper considers a new way for optimal material selection strategy using a combination of three well known methods; the Cambridge Material Selector based method, the adapted value engineering techniques and the technique for order preference by similarity to ideal solution. Using this approach allows the user to combine the strength of each separate method, allowing the material selection process to be streamlined. The novel method is applied in a case study that considers the optimal selection of wave energy extraction Turbine blade material. The results are consistent for such an application, where the optimum material for manufacturing an Impulse Turbine blade would be GFRP, with titanium alloys in second place. This rational method is used directly for choosing a Turbine blade component material and can also be extended to cover other rotating machinery (fans, pumps) or any industrial interest where the common goal is to make an informed decision.
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3-D CFD analysis on effect of hub-to-tip ratio on performance of Impulse Turbine for wave energy conversion
Thermal Science, 2007Co-Authors: A. Thakker, Mohammed A. ElhemryAbstract:This paper deals with the computational fluid dynamics analysis on effect of hub-to-tip ratio on performance of 0.6 m Impulse Turbine for wave energy conversion. Experiments have been conducted on the 0.6 m Impulse Turbine with 0.6 hub-to-tip ratio to validate the present computational fluid dynamics method and to analyze the aerodynamics in rotor and guide vanes, which demonstrates the necessity to improve the blade and guide vanes shape. Computational fluid dynamics analysis has been made on Impulse Turbine with different hub-to-tip ratio for various flow coefficients. The present computational fluid dynamics model can predict the experimental values with reasonable degree of accuracy. It also showed that the downstream guide vanes make considerable total pressure drop thus reducing the performance of the Turbine. The computational fluid dynamics results showed that at the designed flow coefficient of 1.0 the Turbine with 0.5 hub-to-tip ratio has better performance compared to 0.55 and 0.6 hub-to-tip ratio Turbine.
Manabu Takao - One of the best experts on this subject based on the ideXlab platform.
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A pump system with wave powered Impulse Turbine
IOP Conference Series: Earth and Environmental Science, 2019Co-Authors: Y. Kinoue, S. Okuhara, M. M. Ashraful Alam, H Maeda, Norimasa Shiomi, Masaki Sakaguchi, Manabu TakaoAbstract:Japan is surrounded on all sides by the sea. Thus, ocean development has been carried out in the midst of environmental protection. In this consequence, a numerous researches have been conducted on various apparatus that can utilize the wave energy. In this study, a pump system based on the wave energy was developed for pumping the seawater, the facility uses (e.g. aquarium, swimming pool with seawater, etc...), the preservation of farming conditions of marine products, and the replacement of seawater by pumping of the deep water. A radial pump that can be operated by an Impulse Turbine used for wave energy conversion was developed. The performance of this pump system was investigated experimentally. From the experimental results, the pump system could be started approximately in 20 seconds.
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A Counter-Rotating Impulse Turbine for Wave Energy Conversion
Open Journal of Fluid Dynamics, 2018Co-Authors: Manabu Takao, S. Okuhara, Y. Kinoue, Kohei Yamada, M. M. Ashraful Alam, Toshiaki SetoguchiAbstract:Wave energy can be converted to the electrical energy by using a wave energy converter. The wave energy converter with oscillating water column (OWC) is one of the most promising devices because of its simple structure and easy maintenance. In this device, an oscillating water column due to the wave motion is used to drive an air column. An air Turbine is used to convert the pneumatic energy of this bi-directional airflow into the mechanical energy. The counter-rotating Impulse Turbine for wave energy conversion has been proposed and tested so far, and the average efficiency has been shown to about 0.3. On the contrary, in another offshore experiment, it has been reported that the power generation efficiency of this Turbine is larger than Wells Turbine in case of small waves. However, there is a scarcity of the detailed characteristics data of counter-rotating Impulse Turbine. In a previous study, the authors investigated the effect of rotor blade solidity and setting angle of guide vane on the performance of this Turbine, and they clarified that the efficiency of this Turbine is higher than Impulse Turbine with single rotor in the range of high flow coefficients. The present study aimed to investigate the effect of rotor blade profile on the Turbine performance by using the computation fluid dynamic (CFD) analysis. The inner and outer angles of Turbine rotor blade are changed in the range of 50° to 70°. The commercial CFD software of SCRYU/Tetra of Cradle Co. Ltd. was used in the present work. The Reynolds averaged Navier-Stokes (RANS) equations were used as the governing equations and the low Reynold’s number SST k-ω model was used to predict the turbulent stresses. As a result, it was found that the inner angle of γ = 70° and the outer angle of γ = 60° of the Turbine rotor blades can give the best Turbine efficiency and it shows the efficiency close to the Impulse Turbine with single rotor, even in the range of low flow coefficients.
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counter rotating Impulse Turbine for wave energy conversion performance improvement by means of middle vane
IEEE International Conference on Renewable Energy Research and Applications, 2017Co-Authors: Manabu Takao, S. Okuhara, Y. Kinoue, Kohei Yamada, M Ashraful M Alam, Shuich NagataAbstract:In a wave energy converter with oscillating water column (OWC), an OWC due to the sea wave motion is used to drive an air column in the air chamber. An air Turbine for this bidirectional airflow is used to convert the pneumatic energy into the mechanical energy. In this study, in order to achieve further improvement of the performance of a counter-rotating Impulse Turbine, the effect of Turbine geometry on the performance was investigated by using the computation fluid dynamic (CFD) analyses. As a result, it was found that the efficiency of the Turbine greatly increased by installing the middle vanes.
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Counter-rotating Impulse Turbine for wave energy conversion — Performance improvement by means of middle vane
2017 IEEE 6th International Conference on Renewable Energy Research and Applications (ICRERA), 2017Co-Authors: Manabu Takao, S. Okuhara, Y. Kinoue, Kohei Yamada, M. M. Ashraful Alam, Shuich NagataAbstract:In a wave energy converter with oscillating water column (OWC), an OWC due to the sea wave motion is used to drive an air column in the air chamber. An air Turbine for this bidirectional airflow is used to convert the pneumatic energy into the mechanical energy. In this study, in order to achieve further improvement of the performance of a counter-rotating Impulse Turbine, the effect of Turbine geometry on the performance was investigated by using the computation fluid dynamic (CFD) analyses. As a result, it was found that the efficiency of the Turbine greatly increased by installing the middle vanes.
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A Twin Unidirectional Impulse Turbine With Fluidic Diode for Wave Energy Conversion
Volume 1A: Symposia Part 2, 2015Co-Authors: Hideki Sato, M. M. Ashraful Alam, Manabu Takao, Shinya Okuhura, Toshiaki SetoguchiAbstract:As an air Turbine equipped with oscillating water column (OWC) based wave energy plant, a rectification-valve system has been invented to date. However, this Turbine system has problems with the durability of the valves and the complex mechanism. Moreover, it has a major fault in that the valves must be large for high output. Therefore, a twin unidirectional Impulse Turbine topology has been suggested in previous studies in order to use conventional unidirectional Turbines without valves [1, 2]. The topology is composed of two unidirectional Impulse Turbines. However, the past study indicated that the mean efficiency of the topology was shown to be low, when the performance prediction of the topology in oscillating airflow was carried out by means of quasi-steady analysis [2]. Further, the cause of the low efficiency is because part of the air flow gets through the unidirectional Impulse Turbine in the direction of low efficiency [2].In this study, a fluidic diode [3, 4] is adopted in order to suppress the air flow rate into the inefficient Turbine in a twin unidirectional Impulse Turbine topology for wave energy plant, and the effect of the fluidic diodes on the performance of twin unidirectional Impulse Turbine topology is investigated by a wind tunnel test and computational fluid dynamics (CFD). Further, its usefulness is discussed from a view point of the Turbine mean efficiency under unsteady flow condition.Copyright © 2015 by JSME
Toshiaki Setoguchi - One of the best experts on this subject based on the ideXlab platform.
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A Counter-Rotating Impulse Turbine for Wave Energy Conversion
Open Journal of Fluid Dynamics, 2018Co-Authors: Manabu Takao, S. Okuhara, Y. Kinoue, Kohei Yamada, M. M. Ashraful Alam, Toshiaki SetoguchiAbstract:Wave energy can be converted to the electrical energy by using a wave energy converter. The wave energy converter with oscillating water column (OWC) is one of the most promising devices because of its simple structure and easy maintenance. In this device, an oscillating water column due to the wave motion is used to drive an air column. An air Turbine is used to convert the pneumatic energy of this bi-directional airflow into the mechanical energy. The counter-rotating Impulse Turbine for wave energy conversion has been proposed and tested so far, and the average efficiency has been shown to about 0.3. On the contrary, in another offshore experiment, it has been reported that the power generation efficiency of this Turbine is larger than Wells Turbine in case of small waves. However, there is a scarcity of the detailed characteristics data of counter-rotating Impulse Turbine. In a previous study, the authors investigated the effect of rotor blade solidity and setting angle of guide vane on the performance of this Turbine, and they clarified that the efficiency of this Turbine is higher than Impulse Turbine with single rotor in the range of high flow coefficients. The present study aimed to investigate the effect of rotor blade profile on the Turbine performance by using the computation fluid dynamic (CFD) analysis. The inner and outer angles of Turbine rotor blade are changed in the range of 50° to 70°. The commercial CFD software of SCRYU/Tetra of Cradle Co. Ltd. was used in the present work. The Reynolds averaged Navier-Stokes (RANS) equations were used as the governing equations and the low Reynold’s number SST k-ω model was used to predict the turbulent stresses. As a result, it was found that the inner angle of γ = 70° and the outer angle of γ = 60° of the Turbine rotor blades can give the best Turbine efficiency and it shows the efficiency close to the Impulse Turbine with single rotor, even in the range of low flow coefficients.
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A Twin Unidirectional Impulse Turbine With Fluidic Diode for Wave Energy Conversion
Volume 1A: Symposia Part 2, 2015Co-Authors: Hideki Sato, M. M. Ashraful Alam, Manabu Takao, Shinya Okuhura, Toshiaki SetoguchiAbstract:As an air Turbine equipped with oscillating water column (OWC) based wave energy plant, a rectification-valve system has been invented to date. However, this Turbine system has problems with the durability of the valves and the complex mechanism. Moreover, it has a major fault in that the valves must be large for high output. Therefore, a twin unidirectional Impulse Turbine topology has been suggested in previous studies in order to use conventional unidirectional Turbines without valves [1, 2]. The topology is composed of two unidirectional Impulse Turbines. However, the past study indicated that the mean efficiency of the topology was shown to be low, when the performance prediction of the topology in oscillating airflow was carried out by means of quasi-steady analysis [2]. Further, the cause of the low efficiency is because part of the air flow gets through the unidirectional Impulse Turbine in the direction of low efficiency [2].In this study, a fluidic diode [3, 4] is adopted in order to suppress the air flow rate into the inefficient Turbine in a twin unidirectional Impulse Turbine topology for wave energy plant, and the effect of the fluidic diodes on the performance of twin unidirectional Impulse Turbine topology is investigated by a wind tunnel test and computational fluid dynamics (CFD). Further, its usefulness is discussed from a view point of the Turbine mean efficiency under unsteady flow condition.Copyright © 2015 by JSME
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A Twin Unidirectional Impulse Turbine for Wave Energy Conversion: Effect of Rotor Blade Profile on the Performance
Volume 1A: Symposia Part 2, 2015Co-Authors: Manabu Takao, S. Okuhara, Hideki Sato, Miah Md. Ashraful Alam, Genya Masaki, Toshiaki SetoguchiAbstract:There is a twin unidirectional Impulse Turbine topology in an oscillating water column for wave energy conversion, which has two unidirectional Impulse Turbines. In this topology, an oscillating airflow is rectified by these Turbines. Previous studies show that the mean efficiency of this topology is predicted to be lower than the efficiency of a unidirectional Impulse Turbine. Therefore, the rectification of this topology needs more improvement. The objective of this study is to investigate the effect of the rotor blade profile on the performance of twin unidirectional Impulse Turbine by a wind tunnel test and computational fluid dynamics (CFD). In this study, 2 types of the rotor blade profiles in two cases of setting angles of guide vanes has been examined. As a result, the peak efficiency of Type A with θ = 14° was the highest of all Turbines tested in this study. Furthermore, the flow state around the rotor and the guide vane is discussed.Copyright © 2015 by JSME
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Wells Turbine for Wave Energy Conversion —Improvement of the Performance by Means of Impulse Turbine for Bi-Directional Flow
Open Journal of Fluid Dynamics, 2013Co-Authors: S. Okuhara, Akiyasu Takami, Manabu Takao, Toshiaki SetoguchiAbstract:Wells Turbine has inherent disadvantages in comparison with conventional Turbines: relative low efficiency at high flow coefficient and poor starting characteristics. To solve these problems, the authors propose Wells Turbine with booster Turbine for wave energy conversion, in order to improve the performance in this study. This Turbine consists of three parts: a large Wells Turbine, a small Impulse Turbine with fixed guide vanes for oscillating airflow, and a generator. It was conjectured that, by coupling the two axial flow Turbines together, pneumatic energy from oscillating airflow is captured by Wells Turbine at low flow coefficient and that the Impulse Turbine gets the energy at high flow coefficient. As the first step of this study on the proposed Turbine topology, the performance of Turbines under steady flow conditions has been investigated experimentally by model testings. Furthermore, we estimate mean efficiency of the Turbine by quasi-steady analysis.
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A Twin Unidirectional Impulse Turbine for Wave Energy Conversion
Open Journal of Fluid Dynamics, 2012Co-Authors: S. Okuhara, Akiyasu Takami, Manabu Takao, Toshiaki SetoguchiAbstract:A twin unidirectional Impulse Turbine has been proposed in order to enhance the performance of wave energy plant. This Turbine system uses two unidirectional Impulse Turbines and their flow direction is different each other. However, the effect of guide vane solidity on the Turbine characteristics has not been clarified to date. The performances of a uni- directional Impulse Turbine under steady flow conditions were investigated experimentally by using a wind tunnel with large piston/cylinder in this study. Then, mean efficiency of the twin Impulse Turbine in bidirectional airflow has been estimated by a quasi-steady analysis using experimental results in order to investigate the effect of guide vane solidity on the performance.
T.s. Dhanasekaran - One of the best experts on this subject based on the ideXlab platform.
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Computed effect of guide vane shape on performance of Impulse Turbine for wave energy conversion
International Journal of Energy Research, 2005Co-Authors: A. Thakker, T.s. DhanasekaranAbstract:This paper deals with the computational fluid dynamics (CFD) analysis on effect of guide vane shape on performance of Impulse Turbine for wave energy conversion. Initially, experiments have been conducted on the Impulse Turbine to validate the present CFD method and to analyse the aerodynamics in rotor and guide vanes, which demonstrates the necessity to improve the guide vanes shape. The results showed that the downstream guide vanes make considerable total pressure drop leads low performance of the Turbine and hence three-dimensional (3-D) inlet and downstream guide vanes have been designed based on well-known vortex theory to improve the efficiency of the Turbine. In order to prove the improvement in efficiency due to 3-D guide vanes, CFD analysis has been made on Impulse Turbine with 2-D and 3-D guide vanes for various flow coefficients. As a result, it is seen that the present CFD model can predict the experimental values with reasonable accuracy. Also, it is showed from the numerical results that the efficiency of the Turbine can be improved by average of 4.5 percentage points by incorporating 3-D guide vanes instead of 2-D guide vanes. The physical reason for improvement in efficiency of the Turbine due to 3-D guide vanes has been explained with the CFD flow insight pictures. As the Turbine operates in fluctuating flow conditions, the performance of the Turbine with 2-D and 3-D guide vanes have been calculated numerically using quasi-steady analysis. Furthermore, the performance of the Turbine has been predicted for one year based on Irish wave climate to show the feasibility of using 3-D guide vanes in actual sea wave conditions.
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Experimental studies on effect of guide vane shape on performance of Impulse Turbine for wave energy conversion
Renewable Energy, 2005Co-Authors: A. Thakker, T.s. Dhanasekaran, J. RyanAbstract:This paper presents the experimental results of effect of guide vane shape on performance of an Impulse Turbine for wave energy conversion. Two types of guide vanes are considered in the present study: two-dimensional (2D) guide vanes and three-dimensional (3D) guide vanes. The previous investigations by the authors revealed that the 2D guide vanes cause large recirculation zones at leading edge of downstream guide vanes, which affect the performance of Turbine considerably. In order to improve the performance of Turbine, three-dimensional guide vanes are designed based on free-vortex theory. Detailed aerodynamic and performance tests have been conducted on Impulse Turbine with the two types of guide vanes. The experiments have been conducted under various inlet conditions such as steady, sinusoidal and random (real Sea) flows. From the results, it was proved that the efficiency of Impulse Turbine has been improved for 4.5% points due to 3D guide vanes. The hysteric characteristic has been noticed from the experimental results of Impulse Turbine with sinusoidal and random flow inlet conditions. Furthermore, it was investigated that the performance of Turbine is considerably more during deceleration of inlet flow than the acceleration in a half cycle of sinusoidal wave.
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Experimental and computational analysis on guide vane losses of Impulse Turbine for wave energy conversion
Renewable Energy, 2005Co-Authors: A. Thakker, T.s. DhanasekaranAbstract:This paper deals with the detailed flow analysis of Impulse Turbine with experimental and computed results for wave energy power conversion. Initially, several turbulence models have been used in two-dimensional (2-D) computational fluid dynamic (CFD) analysis to find a suitable model for this kind of slow speed unconventional Turbine. Experiments have been conducted to validate the CFD results and also to analyze the aerodynamics at various stations of the Turbine. The three-dimensional (3-D) CFD model with tip clearance has been generated to predict the internal flow and to understand the effect of tip clearance leakage flow on behavior of the Turbine in design and off-design conditions. As a result, it is found from the 2-D results that the comparison between computed and experimental data is good, qualitatively and the turbulence model, standard k–e can predict the experimental values reasonably well, especially the efficiency of the Turbine. Experimental results reveal that the downstream guide vanes are more responsible for low efficiency of the Turbine and it is measured that 21% average pressure is lost due to downstream guide vanes. It is proved from the 3-D CFD model with tip clearance that it can predict the experimental values quantitatively and qualitatively. Furthermore, it is estimated from the computed results that the efficiency of the Turbine has been reduced about 4%, due to tip clearance leakage flow at higher flow coefficients.
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computed effects of tip clearance on performance of Impulse Turbine for wave energy conversion
Renewable Energy, 2004Co-Authors: A. Thakker, T.s. DhanasekaranAbstract:Abstract This paper depicts numerical analysis on Impulse Turbine with fixed guide vanes for wave energy conversion. From the previous investigations, it is found that one of the reasons for the mismatch between computed and experimental data is due to neglecting tip clearance ef fect. Hence, a 3-D model with tip clearance has been generated to predict the internal flow and performance of the Turbine. As a result, it is found that the comparison between computed and experimental data is good, quantitatively and qualitatively. Computation has been carried out for various tip clearances to understand the physics of tip leakage flow and effect of tip clearance on performance of such unconventional Turbine. It is predicted that the Turbine with 0.25% tip clearance performs almost similar to the case of without tip clearance for the entire flow coefficients. The designed value of 1% tip clearance has been validated numerically and computed that the efficiency of the Turbine has been reduced around 4%, due to tip clearance flow at higher flow coefficients.
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3-D COMPUTATIONAL FLUID DYNAMIC ANALYSIS OF EFFECT OF TIP CLEARANCE ON THE PERFORMANCE OF Impulse Turbine FOR WAVE ENERGY CONVERSION
International Journal of Computational Engineering Science, 2004Co-Authors: A. Thakker, T.s. Dhanasekaran, Tatsuya Setoguchi, Manabu TakaoAbstract:This paper depicts numerical analysis on Impulse Turbine of 0.6 m diameter with fixed guide vanes for wave energy conversion. From the earlier investigations, it is found that one of the reasons for the mismatch between computed and experimental data is due to neglecting tip clearance effect. Hence, a three-dimensional (3-D) model with tip clearance has been generated with structured grids to predict the internal flow and performance of the Turbine. As a result, it is found that the comparison between computed and experimental data is good. Computation has been carried out for various tip clearances to understand the effect of tip clearance leakage flow on such unconventional Turbine. The change in flow behavior in the Turbine blade passage due to tip clearance flow has been studied by comparing the results with without tip clearance, which is impossible by experiments. It is predicted that the efficiency of the Turbine has been reduced about 4%, due to tip clearance flow at higher flow coefficients.
Shuichi Nagata - One of the best experts on this subject based on the ideXlab platform.
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A twin unidirectional Impulse Turbine topology for OWC based wave energy plants – Experimental validation and scaling
Renewable Energy, 2011Co-Authors: K. Mala, Manabu Takao, S. Santhakumar, Kazutaka Toyota, V. Jayashankar, J. Jayaraj, T. M. Muruganandam, M. Ravindran, T. Setoguchi, Shuichi NagataAbstract:The twin unidirectional Turbine topology was recently proposed with the promise of very significant improvements in the energy capture in Oscillating Water Column (OWC) based wave energy plants. Here, we present the initial results of the experimental validation of the twin unidirectional Impulse Turbine topology. A scale model of the concept was built and tested using simulated bidirectional flow. The model consists of two 165 mm Impulse Turbines each individually coupled to 375 W grid connected induction machines. An oscillatory flow test rig was used to simulate bidirectional flow to test the model. The results of the experiments validate the concept of the twin Turbine configuration. The proposed topology utilizes no moving parts and achieves more than 50% efficiency over a broad range of flow coefficients. A comparison with other competing Turbines (viz, a twin Wells’ Turbine, a linked guide vane Impulse Turbine and a fixed guide vane Impulse Turbine) is done, based on actual measurements in the Indian wave energy plant. The results from the experiments are scaled to evaluate the design features of a 50 GWh wave energy plant.
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a twin unidirectional Impulse Turbine topology for owc based wave energy plants experimental validation and scaling
Renewable Energy, 2011Co-Authors: K. Mala, Manabu Takao, S. Santhakumar, Kazutaka Toyota, V. Jayashankar, J. Jayaraj, T. M. Muruganandam, M. Ravindran, T. Setoguchi, Shuichi NagataAbstract:The twin unidirectional Turbine topology was recently proposed with the promise of very significant improvements in the energy capture in Oscillating Water Column (OWC) based wave energy plants. Here, we present the initial results of the experimental validation of the twin unidirectional Impulse Turbine topology. A scale model of the concept was built and tested using simulated bidirectional flow. The model consists of two 165 mm Impulse Turbines each individually coupled to 375 W grid connected induction machines. An oscillatory flow test rig was used to simulate bidirectional flow to test the model. The results of the experiments validate the concept of the twin Turbine configuration. The proposed topology utilizes no moving parts and achieves more than 50% efficiency over a broad range of flow coefficients. A comparison with other competing Turbines (viz, a twin Wells’ Turbine, a linked guide vane Impulse Turbine and a fixed guide vane Impulse Turbine) is done, based on actual measurements in the Indian wave energy plant. The results from the experiments are scaled to evaluate the design features of a 50 GWh wave energy plant.
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a twin unidirectional Impulse Turbine topology for owc based wave energy plants
Renewable Energy, 2009Co-Authors: V. Jayashankar, Manabu Takao, S. Santhakumar, Kazutaka Toyota, M. Ravindran, T. Setoguchi, S Anand, T Geetha, Jagadeesh V Kumar, Shuichi NagataAbstract:Experimental results from near shore bottom standing OWC based wave energy plants in Japan and India have now been available for about a decade. Historically the weakest link in the conversion efficiency of OWC based wave energy plants built so far has been the bidirectional Turbine. This is possibly because a single Turbine has been required to deliver power when the plant is exposed to random incident wave excitation varying by a factor of 10. A new topology that uses twin unidirectional Turbines (which features a high efficiency spanning a broad range) is proposed. Using the Indian Wave Energy plant as a case study, it is shown that the power output from such a module considerably exceeds existing optimal configurations including those based on a fixed guide vane Impulse Turbine, linked guide vane Impulse Turbine or a Well's Turbine. A wave to wire efficiency of the order of 50% over the incident range is shown to be feasible in a credible manner by showing the output at all stages of the conversion process. A frequency domain technique is used to compute the OWC efficiency and a time domain approach used for the power module with the Turbine pressure being the pivotal variable.
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performance prediction of owc type small size wave power device with Impulse Turbine
Journal of Fluid Science and Technology, 2008Co-Authors: Masami Suzuki, Manabu Takao, Shuichi Nagata, Kazutaka Toyota, Eiji Satoh, Toshiaki SetoguchiAbstract:This paper investigates a small size wave power device with an Impulse Turbine installed in the breakwater near Niigata Port, Japan. The device consists of an air chamber, a Turbine, a generator and pressure-relief valves. This study reveals the characteristics of each component in this system with Impulse Turbine and a direct current dynamo the power of which is consumed by a constant resistor. In this paper special features of the Impulse Turbine are found, and the system characteristics are briefly represented. The overall plant performance was analyzed using mathematical model of an oscillating water column (OWC) based on linear water wave theory and the special features of the Impulse Turbine.
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A Sea Trial of Wave Power Plant With Impulse Turbine
Volume 6: Nick Newman Symposium on Marine Hydrodynamics; Yoshida and Maeda Special Symposium on Ocean Space Utilization; Special Symposium on Offshore, 2008Co-Authors: Manabu Takao, Eiji Sato, Shuichi Nagata, Kazutaka Toyota, Toshiaki SetoguchiAbstract:A sea trial of wave power plant using an Impulse Turbine with coreless generator has been carried out at Niigata-nishi Port, in order to demonstrate usefulness of the Turbine for wave energy conversion. Oscillating water column (OWC) based wave power plant has been installed at the side of a breakwater and has an air chamber with a sectional area of 4 m2 (= 2m × 2m). The Impulse Turbine used in the sea trial has fixed guide vanes both upstream and downstream, and these geometries are symmetrical with respect to the rotor centerline in order to rotate in a single direction in bi-directional airflow generated by OWC. The Turbine is operated at lower rotational speed in comparison with conventional Turbines. The rotor has a tip diameter of 458 mm, a hub-to-tip ratio of 0.7, a tip clearance of 1 mm, a chord length of 82.8 mm and a solidity of 2.0. The guide vane with chord length of 107.4 mm is symmetrically installed at the distance of 30.7 mm downstream and upstream of the rotor. The guide vane has a solidity of 2.27, a thickness ratio of 0.0279, a guide vane setting angle of 30° and a camber angle of 60°. The generator is coreless type and can generate electricity at lower rotational speed in comparison with conventional generator. The rated and maximum powers of the generator are 450 W and 880 W respectively. The experimental data obtained in the sea trial of wave power plant with the Impulse Turbine having coreless generator was compared to these of Wells Turbine which is the mainstream of the Turbine for wave energy conversion. As a result, total efficiency of the plant using the Impulse Turbine was higher than that of Wells Turbine.Copyright © 2008 by ASME
