Study of turbine with self-pitch-controlled blades for wave energy conversion
TL;DR: In this article, the authors clarified the performance of a Wells air turbine using self-pitch-controlled blades under real sea conditions and obtained the useful information about the optimum setting angle.
Abstract: The objective of this paper is to clarify the performance of a Wells air turbine using self-pitch-controlled blades under the real sea conditions and to obtain the useful information about the optimum setting angle. Experimental investigations were performed by model testing of a rotor with fixed blades under steady flow conditions. Then, the running and starting characteristics under sinusoidally oscillating flow conditions were obtained by a computer simulation using a quasi-steady analysis. As a result, the performances of the air turbine using self-pitch-controlled blades under the real sea conditions were clarified, and a suitable choice of design factor has been suggested for the setting angle of the rotor.
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01 Jan 2012
TL;DR: The comprehensive renewable energy reference work as discussed by the authors is a multi-volume reference work of its type at a time when renewable energy sources are seen increasingly as realistic alternatives to fossil fuels, and can be considered the definitive work for this subject area.
Abstract: "Comprehensive Renewable Energy" is the only multi-volume reference work of its type at a time when renewable energy sources are seen increasingly as realistic alternatives to fossil fuels. As the majority of information published for the target audience is currently available via a wide range of journals, seeking relevant information (be that experimental, theoretical, and computational aspects of either a fundamental or applied nature) can be a time-consuming and complicated process. "Comprehensive Renewable Energy" is arranged according to the most important themes in the field (photovoltaic technology; wind energy technology; fuel cells and hydrogen technology; biomass and biofuels production; hydropower applications; solar thermal systems: components and applications; geothermal energy; ocean energy), and as such users can feel confident that they will find all the relevant information in one place, with helpful cross-referencing between and within all the subject areas, to broaden their understanding and deepen their knowledge. It is an invaluable resource for teaching as well as in research. Available online via SciVerse ScienceDirect and in print. Editor-in Chief, Professor Ali Sayigh (Director General of WREN (World Renewable Energy Network) and Congress Chairman of WREC (World Renewable Energy Congress, UK) has assembled an impressive, world-class team of Volume Editors and Contributing Authors. Each chapter has been painstakingly reviewed and checked for consistent high quality. The result is an authoritative overview which ties the literature together and provides the user with a reliable background information and citation resource. The field of renewable energy counts several journals that are directly and indirectly concerned with the field. There is no reference work that encompasses the entire field and unites the different areas of research through deep foundational reviews. "Comprehensive Renewable Energy" fills this vacuum, and can be considered the definitive work for this subject area. It will help users apply context to the diverse journal literature offering and aid them in identifying areas for further research. Research into renewable energy is spread across a number of different disciplines and subject areas. These areas do not always share a unique identifying factor or subject themselves to clear and concise definitions. This work unites the different areas of research and allows users, regardless of their background, to navigate through the most essential concepts with ease, saving them time and vastly improving their understanding. There are more than 1000 references from books, journals and the internet within the eight volumes. It is full of color charts, illustrations and photographs of real projects and research results from around the world. The only reference work available that encompasses the entire field of renewable energy and unites the different areas of research through deep foundational reviews. Allows readers, regardless of their background, to navigate through the most essential concepts with ease, saving them time and vastly improving their understanding.
122 citations
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TL;DR: In this paper, the authors presented the aerodynamic theory of axial-flow turbines and applied it to the Wells turbine and the impulse turbine, including their variants, in order to analyze their integration into the OWC wave energy converter.
Abstract: Air turbines are used to equip oscillating water column wave energy converters. In almost every case, self-rectifying turbines have been adopted which do not require non-return valves to rectify the reciprocating air flow induced by the water column oscillations. The most frequently used or proposed self-rectifying air turbines are the Wells turbine and the impulse turbine, both of axial-flow type. The fundamentals of the aerodynamic theory of axial-flow turbines are presented and then applied to the Wells turbine and the impulse turbine, including their variants. Information is given on methods of, and results from, air turbine model testing, as well as on self-rectifying air turbines that equipped or equip prototypes tested in the sea. The final part of the chapter is devoted to the analysis of turbine integration into OWC wave energy converter.
49 citations
TL;DR: In this paper, the authors proposed to improve the aerodynamic efficiency of Wells turbines by optimizing the blade pitch angle, which can substantially improve turbine efficiency while slightly delaying the turbine starting point.
Abstract: Wells turbine is a part of OWC (Oscillating Water Column) which is one of the most practical wave energy converters. However, they suffer low aerodynamic efficiency and consequently low power produced. It is proposed to improve the aerodynamic efficiency of Wells turbines by optimizing the blade pitch angle. A fully automated optimization algorithm is implemented in the present work. Two different airfoil geometries are numerically investigated; the standard NACA 0021 and an airfoil with optimized profile “AOP”. Optimization results show that self pitch control of Wells turbines can substantially improve the turbine efficiency while slightly delaying the turbine starting point. The optimum blade pitch angle depends on airfoil geometry and turbine solidity. Up to 2.3% increase in NACA 0021 turbine efficiency and 6.3% improvement of AOP efficiency are achieved by optimizing the blade pitch angle. Self pitch control is feasible for improving Wells turbine efficiency, especially with the application of inlet guide vanes.
47 citations
42 citations
01 Jan 2011
TL;DR: In this article, an optimization process is employed in order to increase the tangential force induced by a monoplane and two-stage Wells turbine using symmetric airfoil blades as well as by a non-symmetric airfoil blades.
Abstract: Research and development activities in the field of renewable energy have been considerably increased in many countries recently, due to the worldwide energy crisis. Wind energy is becoming particularly important. Although considerable progress have already been achieved, the available technical design is not yet adequate to develop reliable wind energy converters for conditions corresponding to low wind speeds and urban areas. The Savonius turbine appears to be particularly promising for such conditions, but suffers from a poor efficiency. The present study considers improved designs in order to increase the output power of a classical Savonius turbine. It aims at improving the output power of the Savonius turbine as well as its static torque, which measures the self-starting capability of the turbine. In order to achieve both objectives, many designs have been investigated and optimized by placing in an optimal manner an obstacle plate shielding the returning blade. The geometry of the blade shape (skeleton line) has been optimized in presence of the obstacle plate. Finally, frontal guiding plates have been considered and lead to a superior performance of Savonius turbines. The optimization process is realized by coupling an in-house optimization library (OPAL, relying in the present case on Evolutionary Algorithms) with an industrial flow simulation code (ANSYS-Fluent). The target function is the output power coefficient. Compared to a standard Savonius turbine, a relative increase of the power output coefficient by 58% is finally obtained at design point. The performance increases throughout the useful operating range. The static torque is found to be positive at any angle, high enough to obtain self-starting conditions. Considering now ocean’s and sea’s energy, the Wells turbine is one of the technical systems allowing an efficient use of the power contained in waves with a relatively low investment level. It consists of a self-rectifying air flow turbine employed to convert the pneumatic power of the air stream induced by an Oscillating Water Column into mechanical energy. On the other hand, standard Wells turbines show several well-known disadvantages: a low tangential force, leading to a low power output from the turbine; a high undesired axial force; usually a low aerodynamic efficiency and a limited range of operation due to stall. In the present work an optimization process is employed in order to increase the tangential force induced by a monoplane and two-stage Wells turbine using symmetric airfoil blades as well as by a two-stage Wells turbine using non-symmetric airfoil blades. The automatic optimization procedure in this part of the work is again carried out by coupling the in-house optimization library OPAL with
40 citations
Cites methods from "Study of turbine with self-pitch-co..."
...2 Self-pitch-controlled blades Experimental investigations were performed by model testing of the rotor with fixed blades under steady flow conditions [32, 44, 56, 60, 99, 100, 101, 106, 120]....
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References
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01 Jan 2002
TL;DR: The Mighty Whale is a floating wave power device based on the Oscillating Water Column (OWC) principle, which converts wave energy into electric energy, and produces a relatively calm sea area behind.
Abstract: Mighty Whale is a floating wave power device based on the Oscillating Water Column (OWC) principle. It converts wave energy into electric energy, and produces a relatively calm sea area behind. The open sea tests were begun in September 1998 in Gokasho Bay, Nansei Town, Mie Prefecture. Measurements collected since then include performance data in typhoon seasons. This paper presents the measurements of wave energy absorption, floating body motion, and wave height dissipation. It is expected that these results will be useful in the design of offshore wave power devices in the future.
78 citations
01 Jan 2000
TL;DR: The Mighty Whale as mentioned in this paper was used for open sea tests to investigate the use of wave energy for power generation in Mie Prefecture, Japan, and the results of the tests were summarized in a recent paper.
Abstract: JAMSTEC completed the construction of the prototype device Mighty Whale by May 1998 for open sea tests to investigate practical use of wave energy. Following construction, the prototype was towed to the test location near the mouth of Gokasho Bay in Mie Prefecture. The open sea tests were begun in September 1998, after final positioning and mooring operations were completed. The tests are expected to continue for approximately 2 years. This paper presents an overview of the open sea tests, and summarizes the characteristics of power generation based on the results so far.
59 citations
01 Jan 1998
47 citations
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