Wells Turbine for Wave Energy Conversion —Improvement of the Performance by Means of Impulse Turbine for Bi-Directional Flow

doi:10.4236/OJFD.2013.32A006

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Wells Turbine for Wave Energy Conversion —Improvement of the Performance by Means of Impulse Turbine for Bi-Directional Flow

Journal Article•DOI•

Wells Turbine for Wave Energy Conversion —Improvement of the Performance by Means of Impulse Turbine for Bi-Directional Flow

Shinya Okuhara, Manabu Takao, Akiyasu Takami, Toshiaki Setoguchi

19 Jul 2013-Open Journal of Fluid Dynamics (Scientific Research Publishing)-Vol. 3, Iss: 2, pp 36-41

TL;DR: In this article, the authors proposed a Wells turbine with a booster turbine for wave energy conversion, which consists of three parts: a large Wells turbine, a small impulse turbine with fixed guide vanes for oscillating airflow, and a generator.

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Abstract: 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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Journal Article•DOI•

Wells turbine for wave energy conversion: a review

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Ahmed S. Shehata¹, Ahmed S. Shehata², Qing Xiao², Khalid M. Saqr¹, Day Alexander² - Show less +1 more•Institutions (2)

Arab Academy for Science, Technology & Maritime Transport¹, University of Strathclyde²

01 Jan 2017-International Journal of Energy Research

TL;DR: In this article, the authors provide an updated and a comprehensive account of the state of the art research on Wells turbine and draw a roadmap for the contemporary challenges which may hinder future reliance on such systems in the renewable energy sector.

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Abstract: In the past twenty years, the use of wave energy systems has significantly increased, generally depending on the oscillating water column (OWC) concept. Wells turbine is one of the most efficient OWC technologies. This article provides an updated and a comprehensive account of the state of the art research on Wells turbine. Hence, it draws a roadmap for the contemporary challenges which may hinder future reliance on such systems in the renewable energy sector. In particular, the article is concerned with the research directions and methodologies which aim at enhancing the performance and efficiency of Wells turbine. The article also provides a thorough discussion of the use of computational fluid dynamics (CFD) for performance modeling and design optimization of Wells turbine. It is found that a numerical model using the CFD code can be employed successfully to calculate the performance characteristics of W-T as well as other experimental and analytical methods. The increase of research papers about CFD, especially in the last five years, indicates that there is a trend that considerably depends on the CFD method.

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84 citations

Cites background or methods from "Wells Turbine for Wave Energy Conve..."

...Figure 14 Turbines characteristics under steady flow conditions: Flow coefficient variation with the efficiency [26] 2 3...
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...16 An impulse with fixed guide vanes turbine for bi-directional flow is used as the booster 17 turbine in order to improve the efficiency of W-T at high flow coefficient by [26]....
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...28 However, the peak efficiencies are almost the same [26]....
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Journal Article•DOI•

Passive flow control for aerodynamic performance enhancement of airfoil with its application in Wells turbine – Under oscillating flow condition

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Ahmed S. Shehata¹, Qing Xiao, Khalid M. Saqr¹, Khalid M. Saqr², Ahmed Naguib¹, Alexander Day - Show less +2 more•Institutions (2)

Arab Academy for Science, Technology & Maritime Transport¹, South China University of Technology²

15 May 2017-Ocean Engineering

TL;DR: In this article, the authors employed an entropy generation minimization method to examine the impact of the flow control method on the entropy generation characteristics around the turbine blade, which is performed using a time-dependent CFD model of isolated NACA airfoil, which refers to the turbine blades under sinusoidal flow boundary conditions, which emulates the actual operating conditions.

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42 citations

Cites background from "Wells Turbine for Wave Energy Conve..."

...…has shown very promising result in many applications, such as wind turbine in Pope et al. (2010), Baskut et al. (2010, 2011), Redha et al. (2011), Ozgener and Ozgener (2007), Mortazavi et al. (2015), and gas turbine in Şöhret et al. (2015), Ghazikhani et al. (2014), Sue and Chuang (2004), Kim…...
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Journal Article•DOI•

Enhancement of performance of wave turbine during stall using passive flow control: First and second law analysis

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Ahmed S. Shehata¹, Qing Xiao, Mohamed M. Selim¹, A. H. Elbatran¹, Alexander Day - Show less +1 more•Institutions (1)

Arab Academy for Science, Technology & Maritime Transport¹

01 Dec 2017-Renewable Energy

TL;DR: In this article, the authors used an entropy generation minimization method to examine the impact of the multi-suction slots method on the entropy generation characteristics around the turbine blade and found that the airfoil with three suction slots located at 40, 55% and 90% from leading edge in chord percentage gave the highest torque coefficient by 267% before the stall and 51% after the stall.

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31 citations

Journal Article•DOI•

Virtual wave flume and Oscillating Water Column modeled by lattice Boltzmann method and comparison with experimental data

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Yann Thorimbert¹, Jonas Latt¹, Lorenzo Cappietti², Bastien Chopard¹•Institutions (2)

University of Geneva¹, University of Florence²

01 Jun 2016-International Journal of Marine Energy

TL;DR: In this article, a novel approach for simulating Oscillating Water Column (OWC) using lattice Boltzmann method (LBM) is presented. And the experimental and numerical setup are described.

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23 citations

Journal Article•DOI•

Effect of passive flow control on the aerodynamic performance, entropy generation and aeroacoustic noise of axial turbines for wave energy extractor

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Ahmed S. Shehata¹, Ahmed S. Shehata², Qing Xiao², Mohamed A. Kotb¹, Mohamed M. Selim¹, Mohamed M. Selim³, A. H. Elbatran¹, Day Alexander² - Show less +4 more•Institutions (3)

Arab Academy for Science, Technology & Maritime Transport¹, University of Strathclyde², University of Alabama at Birmingham³

01 Jun 2018-Ocean Engineering

TL;DR: In this paper, the authors investigated the effect of the angle of the slot angle on the entropy generation features around the turbine blade and the aerodynamics noise emission from the turbine airfoil during the normal operation.

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19 citations

References

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Journal Article•DOI•

The wells air turbine for wave energy conversion

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Srinivasan Raghunathan¹•Institutions (1)

Queen's University Belfast¹

01 Jan 1995-Progress in Aerospace Sciences

TL;DR: In this article, the performance of a single plane biplane Wells turbine with or without guide vanes is compared with a wave energy device based on the principle of the oscillating water-air column.

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286 citations

"Wells Turbine for Wave Energy Conve..." refers result in this paper

...However, according to previous studies, Wells turbine has inherent disadvantages: low efficiency at high flow coefficient and poor starting characteristics in comparison with conventional turbines because of a severe stall [2-6]....
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...Note that the adopted turbine rotor is the most promising one in previous studies [3,5,6]....
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Journal Article•DOI•

Current status of self rectifying air turbines for wave energy conversion

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Toshiaki Setoguchi¹, Manabu Takao•Institutions (1)

Saga University¹

01 Sep 2006-Energy Conversion and Management

TL;DR: In this article, a review of the state of the art on self rectifying air turbines, which could be used for wave energy conversion, has been presented, and the overall performances of the turbines under irregular wave conditions, which typically occur in the sea, have been evaluated numerically and compared from the viewpoints of their starting and running characteristics.

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221 citations

"Wells Turbine for Wave Energy Conve..." refers result in this paper

...However, according to previous studies, Wells turbine has inherent disadvantages: low efficiency at high flow coefficient and poor starting characteristics in comparison with conventional turbines because of a severe stall [2-6]....
[...]

Journal Article•DOI•

A review of impulse turbines for wave energy conversion

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Toshiaki Setoguchi¹, S. Santhakumar, H Maeda², Manabu Takao¹, Kenji Kaneko¹ - Show less +1 more•Institutions (2)

Saga University¹, Saga Group²

01 Jun 2001-Renewable Energy

TL;DR: In this article, the state of the art in self-rectifying impulse air turbines is reviewed and the optimum parameters for the fixed-guide-vane impulse turbine are also presented.

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206 citations

"Wells Turbine for Wave Energy Conve..." refers background or result in this paper

...Recently, in order to develop a high performance selfrectifying air turbine for wave energy conversion, an impulse turbine for bi-directional flow has been proposed by the authors [10-12]....
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...The experimental results of the model testing show that the efficiency of the impulse turbine is high in a wide range of flow coefficient, though its peak efficiency is almost the same as that of Wells turbine [10-12]....
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...The rotor blade and guide vane are also the most promising one [10-12]....
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The Offshore Floating Type Wave Power Device ”Mighty Whale” Open Sea TestsPerformance of The Prototype –

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Hiroyuki Osawa, Yukihisa Washio, Teruhisa Ogata, Yasusi Tsuritani, Yoshinori Nagata - Show less +1 more

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.

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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.

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78 citations

"Wells Turbine for Wave Energy Conve..." refers background in this paper

...Therefore, although a number of OWC based wave energy plants using Wells turbine have been constructed and tested to date, the total conversion efficiencies of the plants were approximately 15% at the best [7-9]....
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Journal Article•

Study On an Impulse Turbine For Wave Energy Conversion

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Toshiaki Setoguchi¹, Manabu Takao¹, Y. Kinoue¹, Kenji Kaneko¹, S. Santhakumar², Masahiro Inoue³ - Show less +2 more•Institutions (3)

Saga University¹, Indian Institute of Technology Madras², Kyushu University³

30 May 1999-International Journal of Offshore and Polar Engineering

TL;DR: In this paper, the performance of the impulse turbine with fixed guide vanes was compared with that of the Wells turbine with a fixed guide vane, and it was shown that the running and starting characteristics of the latter were superior to those of the former under irregular wave conditions.

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Abstract: The objective of this paper is to clarify the performance of impulse turbine with fixed guide vanes and to compare it with that of Wells turbine with guide vanes. As a result, a suitable choice of the design factors for the impulse turbine was shown for the inlet angle of rotor blade and the shape of guide vane. Furthermore, it was found that the running and starting characteristics of the impulse turbine were superior to those of the Wells turbine under irregular wave condition.

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56 citations

"Wells Turbine for Wave Energy Conve..." refers background or result in this paper

...Recently, in order to develop a high performance selfrectifying air turbine for wave energy conversion, an impulse turbine for bi-directional flow has been proposed by the authors [10-12]....
[...]
...The experimental results of the model testing show that the efficiency of the impulse turbine is high in a wide range of flow coefficient, though its peak efficiency is almost the same as that of Wells turbine [10-12]....
[...]
...The rotor blade and guide vane are also the most promising one [10-12]....
[...]