Loads and Dynamic Response of a Floating Wave Energy Converter due to Regular Waves From CFD Simulations

2016 ◽  
Author(s):  
Anna Büchner ◽  
Thomas Knapp ◽  
Martin Bednarz ◽  
Philipp Sinn ◽  
Arndt Hildebrandt
Keyword(s):  
Dynamic Response ◽  
Boundary Conditions ◽  
Wave Energy ◽  
Single Point ◽  
Breaking Waves ◽  
Wave Energy Converter ◽  
Wave Loads ◽  
Regular Waves ◽  
Energy Converter ◽  
Set Up

The commercial CFD code ANSYS Fluent is used for the three-dimensional estimation of wave loads and the dynamic response of a floating single point wave energy converter of the SINN Power wave power plant due to non-breaking and unidirectional waves in coastal waters. The VoF method is used to model the free surface and wave theories to set up the boundary conditions at the inlet for regular waves. The wave induced vertical motions of the floating module are computed by a sixDoF solver. Preliminary 2D and 3D studies to set up boundary conditions, mesh densities and solver settings were performed. The numerical results were compared to analytical solutions in form of water surface elevations and wave kinematics which showed good agreement. The paper presents the dynamic response of the floating module for different load cases in terms of non-breaking waves. The resulting horizontal and vertical forces at the floating module will be presented and explained by the flow dynamics. Time and space depending velocities and pressure distributions including details on vortex separation will be given, which reveal valuable insights on the contribution of inertia and drag forces leading to the dynamic structural response of the floating devices.

Fatigue Analysis of a Point Absorber Wave Energy Converter Subjected to Passive and Reactive Control

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
A. S. Zurkinden ◽  
S. H. Lambertsen ◽  
L. Damkilde ◽  
Z. Gao ◽  
T. Moan
Keyword(s):  
Fatigue Damage ◽  
Wave Energy ◽  
Stress Responses ◽  
Fatigue Analysis ◽  
Wave Energy Converter ◽  
Wave Loads ◽  
Reactive Control ◽  
Energy Converter ◽  
Set Up ◽  
Frequency Domain Approach

This paper investigates the effect of a passive and reactive control mechanism on the accumulated fatigue damage of a wave energy converter (WEC). Interest is focused on four structural details of the Wavestar arm, which is used as a case study here. The fatigue model is set up as an independent and generic toolbox, which can be applied to any other global response model of a WEC device combined with a control system. The stress responses due to the stochastic wave loads are computed by a finite element method (FEM) model using the frequency-domain approach. The fatigue damage is calculated based on the spectral-based fatigue analysis in which the fatigue is described by the given spectral moments of the stress response. The question will be discussed, which control case is more favorable regarding the tradeoff between fatigue damage reduction and increased power production.

scholarly journals Nonlinear PTO Effect on Performance of Vertical Axisymmetric Wave Energy Converter Using Semi-Analytical Method

2017 ◽  
Vol 24 (s3) ◽  
pp. 49-57 ◽  
Author(s):  
Ming Liu ◽  
Hengxu Liu ◽  
Xiongbo Zheng ◽  
Hailong Chen ◽  
Liquan Wang ◽  
...  
Keyword(s):  
Wave Energy ◽  
Analytical Method ◽  
Renewable Energy Sources ◽  
Single Point ◽  
Ocean Waves ◽  
Wave Energy Converter ◽  
Energy Converter ◽  
Advantages And Disadvantages ◽  
Axisymmetric Wave ◽  
Efficient Power

Abstract The wave energy, as a clean and non-pollution renewable energy sources, has become a hot research topic at home and abroad and is likely to become a new industry in the future. In this article, to effectively extract and maximize the energy from ocean waves, a vertical axisymmetric wave energy converter (WEC) was presented according to investigating of the advantages and disadvantages of the current WEC. The linear and quadratic equations in frequency-domain for the reactive controlled single-point converter property under regular waves condition are proposed for an efficient power take-off (PTO). A method of damping coefficients, theoretical added mass and exciting force are calculated with the analytical method which is in use of the series expansion of eigen functions. The loads of optimal reactive and resistive, the amplitudes of corresponding oscillation, and the width ratios of energy capture are determined approximately and discussed in numerical results.

Latching Control of an OWC Spar-Buoy Wave Energy Converter in Regular Waves

2012 ◽  
Author(s):  
J. C. C. Henriques ◽  
A. F. O. Falcão ◽  
R. P. F. Gomes ◽  
L. M. C. Gato
Keyword(s):  
Water Column ◽  
Wave Energy ◽  
Phase Control ◽  
Wave Energy Converter ◽  
Irregular Waves ◽  
Wave Direction ◽  
Regular Waves ◽  
Energy Converter ◽  
Chamber Volume ◽  
The Time Domain

The present paper concerns an OWC spar-buoy, possibly the simplest concept for a floating oscillating-water-column (OWC) wave energy converter. It is an axisymmetric device (and so insensitive to wave direction) consisting basically of a (relatively long) submerged vertical tail tube open at both ends, fixed to a floater that moves essentially in heave. The length of the tube determines the resonance frequency of the inner water column. The oscillating motion of the internal free surface relative to the buoy, produced by the incident waves, makes the air flow through a turbine that drives an electrical generator. It is well known that the frequency response of point absorbers like the spar buoy is relatively narrow, which implies that their performance in irregular waves is relatively poor. Phase control has been proposed to improve this situation. The present paper presents a theoretical investigation of phase control by latching of an OWC spar-buoy in which the compressibility of air in the chamber plays an important role (the latching is performed by fast closing and opening an air valve in series with the turbine). In particular such compressibility may remove the constraint of latching threshold having to coincide with an instant of zero relative velocity between the two bodies (in the case under consideration, between the floater and the OWC). The modelling is performed in the time domain for a given device geometry, and includes the numerical optimization of the air turbine rotational speed, chamber volume and latching parameters. Results are obtained for regular waves.

scholarly journals The power-capture of a nearshore, modular, flap-type wave energy converter in regular waves

2017 ◽  
Vol 137 ◽  
pp. 394-403 ◽  
Author(s):  
L. Wilkinson ◽  
T.J.T. Whittaker ◽  
P.R. Thies ◽  
S. Day ◽  
D. Ingram
Keyword(s):  
Wave Energy ◽  
Wave Energy Converter ◽  
Regular Waves ◽  
Energy Converter ◽  
Type Wave ◽  
Power Capture

scholarly journals CFD Simulations of Floating Point Absorber Wave Energy Converter Arrays Subjected to Regular Waves

Energies ◽  
2018 ◽  
Vol 11 (3) ◽  
pp. 641 ◽  
Author(s):  
Brecht Devolder ◽  
Vasiliki Stratigaki ◽  
Peter Troch ◽  
Pieter Rauwoens
Keyword(s):  
Wave Energy ◽  
Wave Energy Converter ◽  
Floating Point ◽  
Regular Waves ◽  
Energy Converter ◽  
Cfd Simulations ◽  
Point Absorber
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