Efficiency Optimization in Low Inertia Wells Turbine-Oscillating Water Column Devices

2013 ◽  
Vol 28 (3) ◽  
pp. 553-564 ◽  
Author(s):  
Salvador Ceballos ◽  
Judy Rea ◽  
Iraide Lopez ◽  
Josep Pou ◽  
Eider Robles ◽  
...  
Keyword(s):  
Water Column ◽  
Oscillating Water Column ◽  
Wells Turbine ◽  
Efficiency Optimization

scholarly journals Computational Fluid Dynamics Model of Wells Turbine for Oscillating Water Column System: A Review

2021 ◽  
Vol 2053 (1) ◽  
pp. 012013
Author(s):  
N. Abdul Settar ◽  
S. Sarip ◽  
H.M. Kaidi
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Water Column ◽  
Cfd Simulation ◽  
Oscillating Water Column ◽  
Wells Turbine ◽  
Flow Problems ◽  
Cfd Models ◽  
Column System ◽  
Cfd Method

Abstract Wells turbine is an important component in the oscillating water column (OWC) system. Thus, many researchers tend to improve the performance via experiment or computational fluid dynamics (CFD) simulation, which is cheaper. As the CFD method becomes more popular, the lack of evidence to support the parameters used during the CFD simulation becomes a big issue. This paper aims to review the CFD models applied to the Wells turbine for the OWC system. Journal papers from the past ten years were summarized in brief critique. As a summary, the FLUENT and CFX software are mostly used to simulate the Wells turbine flow problems while SST k-ω turbulence model is the widely used model. A grid independence test is essential when doing CFD simulation. In conclusion, this review paper can show the research gap for CFD simulation and can reduce the time in selecting suitable parameters when involving simulation in the Wells turbine.

Analysis of the Wells Turbine Structure of an Oscillating Water Column Wave Energy System

2021 ◽  
pp. 53-62
Author(s):  
Mohamed Ali Jemni ◽  
Hamdi Hentati ◽  
Sawsan Elmbarki ◽  
Mohamed Salah Abid
Keyword(s):  
Water Column ◽  
Wave Energy ◽  
Energy System ◽  
Oscillating Water Column ◽  
Wells Turbine

Hydrodynamic Analysis of a Vertical Axisymmetric Oscillating Water Column Device Floating in Finite Depth Waters

2012 ◽  
Author(s):  
Spyros A. Mavrakos ◽  
Dimitrios N. Konispoliatis
Keyword(s):  
Water Column ◽  
Wall Thickness ◽  
Vertical Cylinder ◽  
Finite Depth ◽  
Wave Forces ◽  
Oscillating Water Column ◽  
Wells Turbine ◽  
Present Contribution ◽  
Outer Atmosphere ◽  
Incident Waves

A floating oscillating water column device (OWC) consists of a vertical cylinder, with a finite wall thickness, partly submerged as an open-bottom chamber in which air is trapped above the inner water free surface. The chamber is connected with the outer atmosphere by a duct housing an air turbine. Forced by incident waves from any direction, the water surface inside pushes the dry air above through a Wells turbine system to generate power. In the present contribution the volume flows, the wave forces, the added mass and damping coefficients and the mean second-order loads for various configurations of OWC devices are being presented. Finally, it is tested how differentiations in the device’s geometry (wall thickness, draught, shape of the chamber, turbine characterises) affect the inner pressure and as a result the absorbed power by the device.

scholarly journals Self-Adaptive Global-Best Harmony Search Algorithm-Based Airflow Control of a Wells-Turbine-Based Oscillating-Water Column

2020 ◽  
Vol 10 (13) ◽  
pp. 4628 ◽  
Author(s):  
Fares M’zoughi ◽  
Izaskun Garrido ◽  
Aitor J. Garrido ◽  
Manuel De La Sen
Keyword(s):  
Water Column ◽  
Search Algorithm ◽  
Harmony Search ◽  
Harmony Search Algorithm ◽  
The Self ◽  
Oscillating Water Column ◽  
Wells Turbine ◽  
Control Scheme ◽  
Tuning Methods ◽  
Self Adaptive

The Harmony Search algorithm has attracted a lot of interest in the past years because of its simplicity and efficiency. This led many scientists to develop various variants for many applications. In this paper, four variants of the Harmony search algorithm were implemented and tested to optimize the control design of the Proportional-Integral-derivative (PID) controller in a proposed airflow control scheme. The airflow control strategy has been proposed to deal with the undesired stalling phenomenon of the Wells turbine in an Oscillating Water Column (OWC). To showcase the effectiveness of the Self-Adaptive Global Harmony Search (SGHS) algorithm over traditional tuning methods, a comparative study has been carried out between the optimized PID, the traditionally tuned PID and the uncontrolled OWC system. The results of optimization showed that the Self-Adaptive Global Harmony Search (SGHS) algorithm adapted the best to the problem of the airflow control within the wave energy converter. Moreover, the OWC performance is superior when using the SGHS-tuned PID.

scholarly journals Control strategies for combining local energy storage with wells turbine oscillating water column devices

2015 ◽  
Vol 83 ◽  
pp. 1097-1109 ◽  
Author(s):  
Salvador Ceballos ◽  
Judy Rea ◽  
Eider Robles ◽  
Iraide Lopez ◽  
Josep Pou ◽  
...  
Keyword(s):  
Energy Storage ◽  
Water Column ◽  
Control Strategies ◽  
Local Energy ◽  
Oscillating Water Column ◽  
Wells Turbine

Design synthesis of oscillating water column wave energy converters: Performance matching

1997 ◽  
Vol 211 (6) ◽  
pp. 489-505 ◽  
Author(s):  
R Curran ◽  
T P Stewart ◽  
T J T Whittaker
Keyword(s):  
Water Column ◽  
Limited Range ◽  
Power Converter ◽  
Analytical Models ◽  
Wave Power ◽  
Oscillating Water Column ◽  
Wells Turbine ◽  
Design Synthesis ◽  
Wave Energy Converters ◽  
Pneumatic Power

The matching of a Wells air turbine to an oscillating water column (OWC) is addressed, with particular reference to design synthesis at the Islay prototype wave power converter. The level of damping applied by the turbine must optimize the hydraulic performance of the OWC in order to facilitate efficient conversion from wave power to pneumatic power. Furthermore, a Wells turbine is only able to convert pneumatic power to mechanical power over a limited range of flow coefficients. Therefore, the efficient operational range of the turbine must extend over a sufficient and optimal proportion of the range of flow coefficients generated by the OWC. Suitable analytical models that describe the behaviour of the system are presented and subsequently the wave conditions and conversion performance at the Islay plant are outlined in order to exemplify the design synthesis to be achieved.

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.

Modeling and Experiments on an Oscillating Water Column Using a Self-Adaptive Air Turbine and Shutter

2013 ◽  
Author(s):  
Patrick Lorenz ◽  
Richard W. Kimball ◽  
Frank DiBella ◽  
Richard Smith ◽  
Scott Ring
Keyword(s):  
Numerical Model ◽  
Water Column ◽  
Potential Flow ◽  
Numerical Models ◽  
Air Flow ◽  
Chamber Pressure ◽  
Oscillating Water Column ◽  
Cavity Pressure ◽  
Wells Turbine ◽  
Physical Scale

This paper presents model-scale measurements and numerical models of a floating oscillating water column (OWC) system, consisting of an air cavity coupled with a Wells-type turbine energy extraction device. As waves travel through the OWC, air pressure cycles are generated. The oscillating water column captures the resulting pneumatic energy by directing the chamber pressure and air flow through the Wells turbine. A special feature of the system is a shuttering device that momentarily interrupts turbine air flow. The shuttering device is used to control the cavity pressure for optimum turbine performance. Shuttering in this manner can be shown to improve overall system efficiency up to 20% pressure. Physical scale models of the OWC system were tested in a wave tank at Maine Maritime Academy (MMA) at 1/30th scale as well as elastomeric diaphragm testing at 1/15th scale, under various conditions. Data from these tests, including cavity pressure response, turbine flow rate, and computed fluid power are discussed. In addition, numerical models of the system were developed using a parametric spring-mass-dashpot methodology and as well as a potential flow model derived for cavity geometry in a global wave field (see section 3). This paper describes the OWC system with adaptive shutter; comparison of experimental measurements to numerical model predictions; numerical model implementation and measurements of energy absorption/resonant effects within the chamber; and a potential flow derivation.

A detailed analysis of the unsteady flow within a Wells turbine

2017 ◽  
Vol 231 (3) ◽  
pp. 197-214 ◽  
Author(s):  
Tiziano Ghisu ◽  
Pierpaolo Puddu ◽  
Francesco Cambuli
Keyword(s):  
Detailed Analysis ◽  
Water Column ◽  
Wave Energy ◽  
Oscillating Water Column ◽  
Renewable Energy Resources ◽  
Wells Turbine ◽  
Column System ◽  
Flow Parameters ◽  
Important Interaction ◽  
Acceleration And Deceleration

Sea wave energy is one of the main renewable energy resources. Its exploitation is relatively simple and determines a minimum impact on the environment. The system that is most often used for wave energy harvesting is composed of an oscillating water column device together with a Wells turbine. When designing the Wells turbine, its interaction with the oscillating water column system must be taken into account, if the energy collected is to be maximized. The most important interaction phenomenon is the so called hysteresis effect, i.e. the time delay between the piston-like motion of the air water interface and the torque developed by the turbine. This work presents a detailed analysis of the flow within an oscillating water column system, focusing on the differences in performance and in secondary flow structures between acceleration and deceleration, and between the inflow and outflow phases. This analysis demonstrates how the hysteresis between acceleration and deceleration is caused uniquely by compressibility effects within the oscillating water column system, while differences in the flow parameters and secondary structures near the rotor are negligible, if equivalent flow conditions are compared. The effects of the oscillating water column system configuration on the performance are also highlighted.

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