High performance ocean energy harvesting turbine design–A new casing treatment scheme

Halder, Paresh; Samad, Abdus; Kim, Jin‐Hyuk; Choi, Young-Seok

doi:10.1016/j.energy.2015.03.131

Cited by 70 publications

(43 citation statements)

References 28 publications

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“…To ensure the numerical accuracy of the simulations performed the present numerical results are validated with the experimental results of Curran and Gato [16] and the numerical results of [13,17,18,19]. The CFD validation of the numerical results is presented in Fig 6. The performance characteristics of the Wells turbine for the entire flow range is plotted and verified.…”

Section: Cfd Validationmentioning

confidence: 62%

Effect of Blade Profiles on the performance of Bidirectional Wave Energy Turbine

Kumar

Samad

2018

MATEC Web of Conferences

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Abstract. To fulfill the ever growing demands of world energy consumption, the wave energy should be extracted economically. The oscillating water column is most commonly used to extract energy from waves. It consists of a chamber in which waves drives the entrapped air column to rotate the Wells turbine. The Wells turbine is a self-rectifying low-pressure axial reaction turbine with 90 ο stagger angle. These turbines consist of symmetrical airfoil profile to achieve unidirectional rotation for the bi-directional airflow. The turbine performance predominantly depends on the aerodynamic characteristics of the airfoil profile used. In this study, the performance of Wells turbine with various symmetrical airfoil profiles was analysed using ANSYS CFX 14.5. The CFD analysis was performed by solving three dimensional steady Reynolds averaged Navier-Stokes equation with k-ω SST turbulence closure model. The reference geometry has NACA0015 as blade profile and the CFD results were compared with the experimental values. The performance characteristics of the new airfoil profiles were compared with the reference case to analyse the suitability of airfoils in wave energy extraction. The NACA0021 airfoil profile showed better performance in the post-stall regime compared to the NACA0015 and the S1046 airfoil profiles.

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Section: Cfd Validationmentioning

confidence: 62%

Effect of Blade Profiles on the performance of Bidirectional Wave Energy Turbine

Kumar

Samad

2018

MATEC Web of Conferences

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“…Wells turbines have been studied extensively, both experimentally [15,31,24,63,74,53,57,48] and numerically [40,62,17,76,30,72,32,27], but mainly from a first-law perspective. More recently, a number of authors [66,67,68,69,71] have focused on the irreversibilities in this component, trying to link the amount of available work (exergy) and the entropy produced.…”

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confidence: 99%

Numerical evaluation of entropy generation in isolated airfoils and Wells turbines

et al. 2018

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In recent years, a number of authors have studied entropy generation in Wells turbines. This is potentially a very interesting topic, as it can provide important insights into the irreversibilities of the system, as well as a methodology for identifying, and possibly minimizing, the main sources of loss. Unfortunately, the approach used in these studies contains some crude simplifications that lead to a severe underestimation of entropy generation and, more importantly, to misleading conclusions. This paper contains a re-examination of the mechanisms for entropy generation in fluid flow, with a particular emphasis on RANS equations. An appropriate methodology for estimating entropy generation in isolated airfoils and Wells turbines is presented. Results are verified for different flow conditions, and a comparison with theoretical values is presented. 1Wells turbines have been studied extensively, both experimentally [15,31,24,63,74,53,57,48] and numerically [40,62,17,76,30,72,32,27], but mainly from a first-law perspective. More recently, a number of authors [66,67,68,69,71] have focused on the irreversibilities in this component, trying to link the amount of available work (exergy) and the entropy produced.The application of second-law analyses is not novel, as such analyses have been done by many authors, but mainly from a system perspective: Bejan [8,9] presents an extensive review of the application to different thermodynamic systems. Similar approaches have been used in the analysis of thermal power plants [39], wind turbines [56,6,7,60,52], and vortex generators [33].Computational Fluid Dynamics (CFD), aside from making possible a more rapid and economic evaluation of many systems (compared to experimental testing), can provide a better and more detailed understanding of many phenomena, by capturing a level of detail that would be extremely difficult in an experimental study. It allows a very fine decomposition of the overall problem that can be used to locate the sources of irreversibility within the system. Entropy generation by thermal and viscous sources can be calculated directly by post-processing the fields of thermo-and fluid-dynamic variables available from the numerical solution [8]. However, particular attention needs to be paid to the nature of the flow and to the solution approach. While in laminar flows all entropy generation is directly found in the CFD solution [18,2,70,33,79,59], this is not true for turbulent flows, unless a Direct Numerical Simulation (or DNS) is used. However, with current computational resources, the use of DNS is still impractical even for moderately large Reynolds numbers. To make high-Reynolds-number flows treatable, the governing equations are either averaged (leading to the Reynolds Averaged Navier Stokes equations, or RANS) or filtered (leading to the Large Eddy Simulation approach, or LES).Moore and Moore [49, 50] present a methodology for calculating entropy production in viscous flows, using RANS equations. They divide the mean entropy production into the contr...

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“…The double-shaft turbines were fitted with an extra bearing assembly, torque and speed transducer, and a generator for the upstream rotor. These experimental work data can be found in many validation cases such as Paresh Halder, et al [203][204][205] and S. Shaaban [99,146], and M. Torresi, et al [37,91]. [93].…”

Section: Validation Of Cfd Modelsmentioning

confidence: 99%

Wells turbine for wave energy conversion: a review

Shehata

Xiao

Saqr

et al. 2016

Int. J. Energy Res.

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Summary In the past 20 years, the use of wave energy systems has significantly increased, generally depending on the oscillating water column concept. Wells turbine is one of the most efficient oscillating water column 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 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 5 years, indicates that there is a trend that considerably depends on the CFD method. Copyright © 2016 John Wiley & Sons, Ltd.

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High performance ocean energy harvesting turbine design–A new casing treatment scheme

Cited by 70 publications

References 28 publications

Effect of Blade Profiles on the performance of Bidirectional Wave Energy Turbine

Effect of Blade Profiles on the performance of Bidirectional Wave Energy Turbine

Numerical evaluation of entropy generation in isolated airfoils and Wells turbines

Wells turbine for wave energy conversion: a review

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