A modified Wells turbine for wave energy conversion
TL;DR: In this paper, the rotor blade pitch was set asymmetrically at a positive pitch to achieve a higher mean efficiency in a wave cycle and the performance characteristics of a turbine with different blade setting angles in steady flow were found by experimentation.
About: This article is published in Renewable Energy.The article was published on 2003-01-01. It has received 84 citations till now. The article focuses on the topics: Oscillating Water Column & Wells turbine.
Citations
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TL;DR: In this paper, a Gurney flap is placed on both pressure and suction sides of the trailing edge (TE) and perpendicular to the chord line without changing chord length.
6 citations
01 Nov 2020
5 citations
01 Apr 2017
TL;DR: In this paper, the authors presented a numerical investigation of the Wells turbine performance operating under steady unidirectional flow conditions, where the turbine was immersed in water and the studied parameters were the turbine efficiency, torque coefficient, and the turbine total pressure drop coefficient.
Abstract: Wells turbine is a self-rectifying turbine capable of converting pneumatic power of the periodically reversing flow (air or water) stream in oscillating ocean waving water column into mechanical energy. However, such turbines suffers from low aerodynamic efficiency, low power produced, and narrow operating range. To enhance the Wells turbine performance, the present work proposed that a new operating concept where the turbine is immersed in water. This gives the privilege of operating the turbine with a fluid having higher specific weight fluid instead of air. This paper presents a numerical investigation of the Wells turbine performance operating under steady unidirectional flow conditions. The studied parameters are the turbine efficiency, torque coefficient, and the turbine total pressure drop coefficient. The results are performed by solving numerically the steady 3D incompressible Reynolds Averaged Navier–Stokes equation (RANS) using ANSYS FLYENT v16.2 commercial code. The results demonstrate that a substantial improvement in the turbine performance where the maximum percentage increase in turbine efficiency is about 4 times its efficiency in air, and the maximum percentage increase in turbine power reaches to 4.5 times increase at flow coefficient of 0.275. Furthermore, and a wider range of operation is achieved by using water instead of air as a working fluid which mean that the stall point is delayed. Using Wells turbine immersed in water is a promising issue for further investigations.
5 citations
Cites background from "A modified Wells turbine for wave e..."
...The effect of geometric parameters on the performance of Wells turbine such as blade geometry [11], blade setting angle [12], use of end plates [13] and tip clearance [14] have been investigated....
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TL;DR: In this paper, the transient behavior of a Wells turbine with both a standard rigid blade and a blade with a flexible trailing edge is investigated, and the effects of various Young's Moduli are tested and their flow fields analyzed.
Abstract:
Direct energy conversion from ocean waves requires some method of rectifying the oscillatory motion to produce a unidirectional output. The Wells turbine accomplishes this with horizontally mounted symmetric blades, which produce a net torque output when combined with an oscillating water column. Previous studies have been conducted, which investigate the effects of blade profile, turbine solidity, stator tip gap clearance, and a number of guide vane designs intended to improve performance. Both experimental and computational methods have been employed, with computational models typically relying on commercially available computational fluid dynamics (CFD) code and assuming steady-state flow conditions. In this work, the open-source code foam-extend is used to study the transient behavior of a Wells turbine, with both a standard rigid blade and a blade with a flexible trailing edge. A validated model is established, and the effects of various Young’s Moduli are tested and their flow fields analyzed. Significant performance gains are realized, with a nearly 17% increase in output torque in some cases.
5 citations
01 Jan 2021
TL;DR: In this paper, the combined effect of tip groove and radiused tip (CG&RT) design modification was investigated to enhance the performance of the Wells turbine in an oscillating water column.
Abstract: The Wells turbine is a self-rectifying air turbine, used in oscillating water column (OWC) to harvest wave energy. It produces unidirectional torque as the flow oscillates inside the OWC chamber. It has inherent disadvantage of narrow operating range due to stall at high airflow rate. Whereas, a wider operating range is essential to improve the turbine power output. A casing groove modifies the tip leakage flow pattern and improves the operating range. In addition, a radiused tip can alter the tip leakage flow and delay the stall. To enhance the performance further, this paper investigates the combined effect of tip groove and radiused tip (CG&RT) design modification. The flow was simulated by solving steady, incompressible Reynolds averaged Navier–Stokes equations in Ansys CFX 15.0. As expected, the CG&RT blade enhanced the relative operating range and the turbine power output by 44.4% and 23.8%, respectively.
4 citations
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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.
286 citations
TL;DR: In this article, the authors investigated the influence of the turbine aerodynamic design on the overall plant performance, as affected by the turbine peak efficiency and the range of flow rates within which the turbine can operate efficiently.
109 citations
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
Journal Article•
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.
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.
56 citations