Comparative study of offshore spar-buoy oscillating water column dynamic models for captured power estimation

2022 ◽  
pp. 147509022110677
Author(s):  
Seif Bayoumi ◽  
Erkan Oterkus ◽  
Hassan El-Gamal ◽  
Atilla Incecik
Keyword(s):  
Water Column ◽  
Wave Energy ◽  
Dynamic Models ◽  
Numerical Solutions ◽  
Coupling Model ◽  
Scale Model ◽  
Oscillating Water Column ◽  
Financial Assessment ◽  
Energy Technologies ◽  
Reduced Scale

The prompt estimation of power and geometrical aspects enables faster and more accurate financial assessment of wave energy converters to be deployed. This may lead to better commercialisation of wave energy technologies, as they require location-based customisation, unlike the mature wind energy technologies with developed benchmark. The adopted approach provides simple and efficient modelling tool allowing the study of the system from different perspective. The aim of this study is to select the optimum dynamic model to predict the captured power of a spar-buoy Oscillating Water Column (OWC) wave energy converter. Four dynamic models were developed to predict the system dynamics and results were validated experimentally. In-depth investigations on the effect of the mass and damping ratios of the oscillating bodies on the accuracy of the adopted models were performed. Such investigations included the proposed one-way coupling model and three two-degree of freedom models and three reduced-scale models, in addition to analytical and numerical solutions. Pneumatic power was calculated for the reduced-scale model where orifices’ covers simulated the power take-off mechanism damping experimentally. Analysis and comparisons between the adopted models are finally provided.

Scale and Configuration Effects of an Airchamber on PTO of Oscillating Water Column Type Wave Energy Converters

2021 ◽  
Author(s):  
Tomoki Ikoma ◽  
Shota Hirai ◽  
Yasuhiro Aida ◽  
Koichi Masuda
Keyword(s):  
Water Column ◽  
Wave Energy ◽  
Water Surface ◽  
Air Pressure ◽  
Scale Model ◽  
Linear Potential ◽  
Oscillating Water Column ◽  
Wave Energy Converters ◽  
Air Chamber ◽  
Energy Converters

Abstract Wave energy converters (WECs) have been extensively researched. The behaviour of the oscillating water column (OWC) in OWC WECs is extremely complex due to the interaction of waves, air, and turbines. Several problems must be overcome before such WECs can be put to practical use. One problem is that the effect of the difference in scale between a small-scale experimental model and a full-scale model is unclear. In this study, several OWC models with different scales and geometries were used in forced oscillation tests. The wave tank was 7.0 m wide, 24.0 m long, and 1.0 m deep. In the static water experiment, we measured the air pressure and water surface fluctuations in an air chamber. For the experiments, models with a box shape with an open bottom, a manifold shape with an open bottom, and a box shape with a front opening, respectively, were fabricated. Furthermore, 1/1, 1/2, and 1/4 scale models were fabricated for each shape to investigate the effects of scale and shape on the air chamber characteristics. Numerical calculations were carried out by applying linear potential theory and the results were compared with the experimental values. The results confirmed that the air chamber shape and scale affect the air pressure fluctuation and water surface fluctuation inside the OWC system.

scholarly journals Numerical prediction of the natural frequency of an Oscillating Water Column operating under resonant conditions

2016 ◽  
Vol 7 (3) ◽  
pp. 100-107 ◽  
Author(s):  
Marco Torresi ◽  
Filippo Scarpetta ◽  
Giuseppina Martina ◽  
Pasquale F Filianoti ◽  
Sergio M Camporeale
Keyword(s):  
Water Column ◽  
Natural Frequency ◽  
Wave Energy ◽  
Scale Model ◽  
Oscillating Water Column ◽  
Sea State ◽  
Submerged Breakwater ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations ◽  
Mass Spring

Among the different technologies developed in order to harness wave energy, the Oscillating Water Column devices are the most accredited for an actual diffusion. Recently, Boccotti has patented the REWEC1 (REsonant sea Wave Energy Converter solution 1), a submerged breakwater that performs an active coast protection, embedding an Oscillating Water Column device, which is capable of operating under resonant conditions with that sea state, which gives the highest yearly energy contribution. The REWEC1 dynamic behavior can be approximated by means of a mass-spring-damper system. According to this approximation, a criterion for evaluating the oscillating natural frequency of the REWEC1 has been derived. This criterion has been validated against both experimental results and computational fluid dynamics simulations, performed on a REWEC1 laboratory-scale model. The numerical simulations have shown a good agreement between measurements and predictions.

Nonlinear 2D analysis of the efficiency of fixed Oscillating Water Column wave energy converters

2014 ◽  
Vol 64 ◽  
pp. 255-265 ◽  
Author(s):  
Yongyao Luo ◽  
Jean-Roch Nader ◽  
Paul Cooper ◽  
Song-Ping Zhu
Keyword(s):  
Water Column ◽  
Wave Energy ◽  
Oscillating Water Column ◽  
Wave Energy Converters ◽  
Energy Converters

Evaluation of 3-D Computational Model of Oscillating Water Column Converter with Constructal Design with Three Degrees of Freedom and Limited Chimney Height

2021 ◽  
Vol 407 ◽  
pp. 128-137
Author(s):  
Vinícius Bloss ◽  
Camila Fernandes Cardozo ◽  
Flávia Schwarz Franceschini Zinani ◽  
Luiz Alberto Oliveira Rocha
Keyword(s):  
Water Column ◽  
Wave Energy ◽  
Degrees Of Freedom ◽  
Numerical Study ◽  
Mechanical Energy ◽  
Ocean Waves ◽  
Response Surfaces ◽  
Oscillating Water Column ◽  
Promising Source ◽  
Three Degrees Of Freedom

Theoretically, ocean waves contain enough mechanical energy to supply the entire world’s demand and, as of late, are seen as a promising source of renewable energy. To this end, several different technologies of Wave Energy Converters (WEC) have been developed such as Oscillating Water Column (OWC) devices. OWCs are characterized by a chamber in which water oscillates inside and out in a movement similar to that of a piston. This movement directs air to a chimney where a turbine is attached to convert mechanical energy. The analysis conducted was based on the Constructive Design Method, in which a numerical study was carried out to obtain the geometric configuration that maximized the conversion of wave energy into mechanical energy. Three degrees of freedom were used: the ratio of height to length of the hydropneumatic chamber (H1/L), the ratio of the height of the chimney to its diameter (H2/d) and the ratio of the width of the hydropneumatic chamber to the width of the wave tank (W/Z). A Design of Experiments (DoE) technique coupled with Central Composite Design (CCD) allowed the simulation of different combinations of degrees of freedom. This allowed the construction of Response Surfaces and correlations for the efficiency of the system depending on the degrees of freedom (width and height of the chamber), as well as the optimization of the system based on the Response Surfaces.

scholarly journals Wave power extraction from a bottom-mounted oscillating water column converter with a V-shaped channel

2014 ◽  
Vol 470 (2167) ◽  
pp. 20140074 ◽  
Author(s):  
Zhengzhi Deng ◽  
Zhenhua Huang ◽  
Adrian W. K. Law
Keyword(s):  
Water Column ◽  
Water Depth ◽  
Wave Energy ◽  
High Efficiency ◽  
Expansion Method ◽  
Opening Angle ◽  
Energy Extraction ◽  
Oscillating Water Column ◽  
Wave Direction ◽  
Power Extraction

An analytical theory is developed for an oscillating water column (OWC) with a V-shaped channel to improve the pneumatic efficiency of wave energy extraction. An eigenfunction expansion method is used in a cylindrical coordinate system to investigate wave interaction with the OWC converter system. Auxiliary functions are introduced to capture the singular behaviours in the velocity field near the salient corners and cusped edges. Effects of the OWC dimensions, the opening angle and length of the V-shaped channel, as well as the incident wave direction, on the pneumatic efficiency of wave energy extraction are examined. Compared with a system without the V-shaped channel, our results show that the V-shaped channel can significantly increase the conversion efficiency and widen the range of wave frequency over which the OWC system can operate at a high efficiency. For typical coastal water depths, the OWC converter system can perform efficiently when the diameter of the OWC chamber is in the range of 1 5 – 1 2 times the water depth, the opening angle of the V-shaped channel is in the range of [ π /2, 3 π /4] and the length of the V-shaped channel is in the range of 1–1.5 times the water depth.

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