scholarly journals Effective Method for Evaluating Airflow Rate of Oscillating-Water-Column Pilot Plants

Processes ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 1884
Author(s):  
Sewan Park ◽  
Kilwon Kim ◽  
Jeong-Hwan Oh ◽  
Chang-Hyuk Lim ◽  
Ji-Yong Park ◽  
...  
Keyword(s):  
Water Column ◽  
Pilot Plant ◽  
Interpolation Method ◽  
Airflow Rate ◽  
Oscillating Water Column ◽  
Impulse Turbine ◽  
Irregular Wave ◽  
Wave States ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations

In this study, a method for effectively estimating the airflow rate of the turbine of an oscillating water column (OWC) pilot plant was developed. The validity of the proposed method was verified through computational fluid dynamics simulations. The method was applied to estimate the airflow rate in irregular wave states based on the operation data obtained for the Yongsoo OWC pilot plant installed in the western seas of Jeju Island, South Korea. As an alternative to estimating the airflow rate of the OWC pilot plant, the impulse turbine performance chart-based interpolation method is introduced, and it is shown that the airflow rate time series calculated using the two methods were in good agreement.

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.

scholarly journals Optimization of Radial Impulse Turbine for Oscillating Water Column Wave Renewable Energy

2019 ◽  
Vol 8 (12) ◽  
pp. 5699-5703
Keyword(s):  
Water Column ◽  
Oscillating Water Column ◽  
Peak Efficiency ◽  
Impulse Turbine ◽  
Trapped Air ◽  
Turbine Efficiency ◽  
Turbine Performance ◽  
Radial Turbine ◽  
Wide Range ◽  
Computational Fluid Dynamics Cfd

An oscillating water column (OWC) extracts the power of waves by trapping air above a water column. This trapped air is compressed and decompressed by the wave action flow inside a turbine power to the mechanical power during process, and it is important as the turbines are expected to operate in oscillating and reversing flows over a wide range of conditions. The objectives of this study are to determine and analyze the type of radial impulse turbine of OWC and to optimize the performance of a radial impulse turbine for OWC by using Computational Fluid Dynamics (CFD). This requires a comprehensive investigation on turbine configuration, turbine efficiency, OWC integration, and turbine operation with respect to climate condition. The outcome of this study to settle the main drawbacks of radial turbine namely lower peak efficiency and damping on OWC can be considered. Later, these problems will be further study to identify the behavior of the airflow through the machine, sources of energy loss, and impact of different parameters on the turbine performance.

scholarly journals DEVELOPMENT OF A NUMERICAL MODEL FOR THE STUDY OF AN OSCILLATING WATER COLUMN DEVICE CONSIDERING AN IMPULSE TURBINE

2019 ◽  
Vol 18 (1) ◽  
pp. 99
Author(s):  
A. L. dos Santos ◽  
L. A. Isoldi ◽  
L. A. O. Rocha ◽  
M. N. Gomes ◽  
R. S. Viera ◽  
...  
Keyword(s):  
Numerical Model ◽  
Energy Conversion ◽  
Water Column ◽  
Numerical Study ◽  
Velocity Ratio ◽  
Power Coefficient ◽  
Working Fluid ◽  
Speed Ratio ◽  
Oscillating Water Column ◽  
Impulse Turbine

The present work brings a numerical study of an energy conversion device which takes energy from the waves through an oscillating water column (OWC), considering an impulse turbine with rotation in the chimney region through the implementation of a movable mesh model. More precisely, a turbulent, transient and incompressible air flow is numerically simulated in a two-dimensional domain, which mimics an OWC device chamber. The objectives are the verification of the numerical model with movable mesh of the impulse turbine in the free domain from the comparison with the literature and, later, the study of the impulse turbine inserted in the geometry of the OWC device. In order to perform the numerical simulation on the generated domains, the Finite Volume Method (FVM) is used to solve the mass and momentum conservation equations. For the closure of the turbulence, the URANS (Unsteady Reynolds Averaged Navier-Stokes) model k-ω SST is used. To verify the numerical model employed, drag coefficients, lift, torque and power are obtained and compared with studies in the literature. The simulations are performed considering a flow with a Reynolds number of ReD = 867,000, air as the working fluid and a tip speed ratio of λ = 2. For the verification case, coefficients similar to those previously predicted in the literature were obtained. For the case where the OWC device was inserted it was possible to observe an intensification of the field of velocities in the turbine region, which led to an augmentation in the magnitude of all coefficients investigated (drag, lift, torque and power). For the case studied with the tip velocity ratio λ = 2, results indicated that power coefficient was augmented, indicating that the insertion of the turbine in a closed enclosure can benefit the energy conversion in an OWC device.

scholarly journals Optimal design of air turbines for oscillating water column wave energy systems: A review

2017 ◽  
Vol 8 (1) ◽  
pp. 37-49 ◽  
Author(s):  
Tapas Kumar Das ◽  
Paresh Halder ◽  
Abdus Samad
Keyword(s):  
Water Column ◽  
Wave Energy ◽  
Guide Vane ◽  
Optimization Techniques ◽  
Maximum Efficiency ◽  
Oscillating Water Column ◽  
Peak Efficiency ◽  
Wells Turbine ◽  
Impulse Turbine ◽  
Operating Range

Oscillating water column wave energy harvesting system uses pneumatic power to run a turbine and generate power. Both reaction (mainly Wells turbine) and impulse type turbines are tested in oscillating water column system and the performances are investigated. Reaction turbines are easy to install, and the operating range is narrow and possesses higher peak efficiency. On the contrary, impulse turbines have the wider operating range and lower peak efficiency. Some of the key parameters for Wells turbine are solidity, tip clearance, and the hub-to-tip ratio. Significant performance improvement is possible by redesigning the turbines using optimization techniques. Till date, surrogate modeling and an automated optimization library OPAL are commonly used in optimization of oscillating water column air turbines. In this article, various types of oscillating water column turbines are reviewed, and optimization techniques applied to such turbines are discussed. The Wells turbine with guide vane has the maximum efficiency, whereas the axial-impulse turbine with pitch-controlled guide vane has the widest operating range. Turbines with optimized geometry have better overall performance than other turbines.

A Tethered Multiple Oscillating Water Column Wave Energy Device: From Concept to Deployment

2002 ◽  
Author(s):  
John Chudley ◽  
Y. Ming Dai ◽  
Fraser Johnson
Keyword(s):  
Engineering Design ◽  
Water Column ◽  
Wave Energy ◽  
Phase Locking ◽  
Wave Climate ◽  
Oscillating Water Column ◽  
Impulse Turbine ◽  
Energy Device ◽  
Local Wave ◽  
The Individual

This paper discusses the research and design methodology employed in the development of a tethered Multiple Oscillating Water Column (MOWC) wave energy device – from concept to deployment. The fundamental aim of the project was the design and deployment of a scaled floating MOWC wave energy device capable of generating physical data from sea trials. The MOWC collector component incorporated oscillating columns connected to a self-rectifying impulse turbine via individual settling chambers. The device has a water draught of 12m and an air draught of 3m. It is of cylindrical design with an overall diameter of 4.4m, displacing 10t The present unit is rated to at 5 kW power output through restrictions of the internal airflows. Research indicates that a full-scale unit 5 times bigger than the scaled device would be capable of generating 500 – 750 kW in a moderately rough sea. The paper addresses the complex problems associated with floating MOWC devices and suggests methods to enable accurate modeling and matching of internal components. Topics discussed include: concept recognition, hydrodynamic motion interaction with OWC, local resource evaluation, turbine selection, power generation and dissipation, moorings, data monitoring, telemetry and performance evaluation. Mathematical simulations and tank testing were used to develop the concept to a stage where an engineering design could be generated. The use of mathematical modelling presented the project with several specific problems that have been highlighted within the paper. Tank testing enabled the project to overcome these difficulties and developed an engineering design tuned to the local wave climate. Initial research has indicated that the combination of individual Oscillating Water Columns (OWC) of different draughts increases the efficiency of this design when compared to a typical single OWC device. Results also indicated that the channeling of individual air masses through a self-rectifying impulse turbine would produce a self-regulated electrical output via phase locking of the individual columns.

Improving the Hydrodynamic Performance of OWC Wave Energy Converter by Attaching a Step

2019 ◽  
Author(s):  
Kourosh Rezanejad ◽  
Jorge F. M. Gadelho ◽  
Ivan López ◽  
Rodrigo Carballo ◽  
C. Guedes Soares
Keyword(s):  
Experimental Study ◽  
Water Column ◽  
Water Depth ◽  
Hydrodynamic Performance ◽  
Experimental Investigations ◽  
Efficiency Improvement ◽  
Oscillating Water Column ◽  
Energy Converter ◽  
Irregular Wave ◽  
Wave Characteristics

Abstract The influence of attaching a step to the conventional shore based Oscillating Water Column device on the hydrodynamic performance has been assessed by carrying out experimental investigations. The level of the efficiency improvement in various wave characteristics and Power Take-Off damping conditions were investigated. Three different Power Take-Off damping conditions have been applied to the system and experiments were carried out for both regular and irregular wave conditions. The results obtained from the experimental study prove that the Oscillating Water Column with the attached step has substantially improved hydrodynamic performance in all the Power Take-Off damping conditions compared to the Oscillating Water Column model in uniform water depth.

Nonlinear NWT Simulation for Oscillating-Water-Column Wave Energy Converter

2010 ◽  
Author(s):  
Weoncheol Koo ◽  
Moo-Hyun Kim
Keyword(s):  
Water Column ◽  
Time Varying ◽  
Numerical Wave Tank ◽  
Oscillating Water Column ◽  
Energy Converter ◽  
Airflow Velocity ◽  
Fully Nonlinear ◽  
Irregular Wave ◽  
Experimental Values ◽  
Nonlinear Free Surface

A two-dimensional time-domain, fully nonlinear numerical wave tank (NWT) technique based on potential theory, the mixed Eulerian-Lagrangian (MEL) approach, and the boundary element method was developed and applied to a land-based oscillating water column (OWC) system with compressed air inside the chamber. The nonlinear free-surface inside the chamber was specially treated to represent both the viscous effect of the water column motion and the pneumatic pressure of the time-varying airflow velocity in the chamber. The developed NWT was verified through comparison with viscous-flow-based numerical and experimental results by Liu et al. (2008) with and without air ducts. The NWT simulations correlated well with experimental values with tuned viscous damping coefficient for a variety of wave conditions. The fully nonlinear simulations were also performed with irregular wave input, so that the developed numerical tool can be practically used for the optimal design of land-based OWCs.

Sign in / Sign up

Export Citation Format

Share Document