Journal ArticleDOI
Wave generation by an oscillating surface-pressure and its application in wave-energy extraction
TLDR
In this paper, a two-dimensional analysis based on linear surface-wave theory is developed for an oscillating-water-column wave-energy device in water of arbitrary constant depth, and the results show that air compressibility can be important in practice, and its effects may in general be satisfactorily represented by linearization.Abstract:
A two-dimensional analysis, based on linear surface-wave theory, is developed for an oscillating-water-column wave-energy device in water of arbitrary constant depth. The immersed part of the structure is assumed of shallow draught except for a submerged vertical reflecting wall. Both the cases of linear and nonlinear power take-off are considered. The results show that air compressibility can be important in practice, and its effects may in general be satisfactorily represented by linearization. The analysis indicates that using a turbine whose characteristic exhibits a phase difference between pressure and flow rate may be a method of strongly reducing the chamber length and turbine size with little change in the capability of energy extraction from regular waves. It was found in two examples of devices with strongly nonlinear power take-off that the maximum efficiency is only marginally inferior to what can be achieved in the linear case.read more
Citations
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Journal ArticleDOI
Three-dimensional CFD simulation of a circular OWC with a nonlinear power-takeoff: Model validation and a discussion on resonant sloshing inside the pneumatic chamber
Conghao Xu,Zhenhua Huang +1 more
TL;DR: In this paper, a three-dimensional numerical simulation of a circular bottom-sitting OWC device for wave energy extraction is presented, which is based on Reynolds-Averaged Navier-Stokes equations with a modified k-ω turbulence model and a volume-of-fluid method to track the air-water surface.
Journal ArticleDOI
Wave power extraction from a bottom-mounted oscillating water column converter with a V-shaped channel
TL;DR: In this paper, an analytical theory for an oscillating water column (OWC) with a V-shaped channel to improve the pneumatic efficiency of wave energy extraction was developed.
Journal ArticleDOI
Diffraction of ocean waves around a hollow cylindrical shell structure
Song-Ping Zhu,Lewis Mitchell +1 more
TL;DR: In this article, a first-order analytical solution for the diffraction of ocean waves around a hollow cylindrical shell structure suspended in an ocean of finite depth is presented, and the accuracy of the solution as a function of cylinder submergence is analyzed.
Journal ArticleDOI
Hydrodynamic performance of a multi-Oscillating Water Column (OWC) platform
Siming Zheng,Siming Zheng,Alessandro Antonini,Yongliang Zhang,Jon Miles,Deborah Greaves,Guixun Zhu,Gregorio Iglesias,Gregorio Iglesias +8 more
TL;DR: In this article, a rectangular barge consisting of multiple oscillating water columns (OWCs) is considered and the effect of the turbine is characterized as a linear power take-off (PTO) system.
Journal ArticleDOI
Time-domain simulation of a slack-moored floating oscillating water column and validation with physical model tests
TL;DR: In this article, a slack-moored Spar-buoy OWC (Oscillating Water Column) wave energy converter is modeled as a rigid body with six degrees of freedom, whereas the free surface is assumed flat.
References
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Surface Waves
TL;DR: In this paper, the evanescent field structure over the wave front, as represented by equiphase planes, is identified as one of the most important and easily recognizable forms of surface wave.
Journal ArticleDOI
Wave-power absorption by systems of oscillating surface pressure distributions
TL;DR: In this article, the efficiency of energy absorption of a system of uniform oscillatory surface pressure distributions was derived based on linear water-wave theory and the results showed the close analogies which exist with theories for absorbing oscillatory rigid bodies and a number of new reciprocal relations for pressure distributions.
Journal ArticleDOI
On the Theory of the Wells Turbine
Luís M.C. Gato,A.F. de O. Falcão +1 more
TL;DR: In this article, the authors present an etude theorique du comportement thermodynamique de la turbine de Wells, a turbine a ecoulement axial adaptee a l'extraction d'energie a partir d'un energy alternatif, and obtention d'expressions for la forme d'ailette rendant maximal le rendement of the turbine.
Book ChapterDOI
Computer oriented algorithms for solving systems of simultaneous nonlinear algebraic equations
TL;DR: In this paper, the authors discuss the problem of solving N real equations in N real unknowns, and present the best algorithms for the various facets of the given system, such as getting into a region of local convergence from poor initial estimates, achieving guaranteed convergence to a root from anywhere within a specified region by suitably restricting the functions fi, using a technique in a vicinity of a root (local technique) which is fast, stable and which does not require the user to furnish derivatives of the function fi; and finally, obtaining additional roots of a nonlinear system without converging again to
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