Effect of Oscillating Water Column Chamber Inclination on the Performance of a Savonius Rotor

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Deepak D. Prasad ◽  
M. Rafiuddin Ahmed ◽  
Young-Ho Lee
Keyword(s):  
Water Column ◽  
Wave Energy ◽  
Hollow Structure ◽  
Flow Characteristics ◽  
Wave Crest ◽  
Oscillating Water Column ◽  
Sea State ◽  
Wave Condition ◽  
Improved Performance ◽  
Incident Waves

Abstract The power potential in the waves that hit all the coasts worldwide has been estimated to be of the order of 1 TW. Each wave crest transmits 10–50 kW/m of energy, which is 15–20 times higher than wind or solar energies. The availability of wave energy is 90% compared to 30% for wind and solar energies. The oscillating water column (OWC), which is the most investigated wave energy converter consists of a partially submerged hollow structure positioned either vertically or inclined. The bidirectional airflow above the water column drives a turbine. The conventional OWCs experience flow separation at the sharp corners of the chamber. To address this issue, researchers have proposed inclining the chamber at an angle with respect to the incident waves to improve the flow characteristics. In the present work, the effect of OWC inclination on rotor performance is studied using the computational fluid dynamics (CFD) code ansys-cfx. The results highlight that the 55 deg inclined OWC showed improved performance compared to the conventional OWC and modified OWC (optimized in a previous work). The maximum power for the inclined OWC was 13% higher than that for the rotor in the modified OWC and 28% than that in the conventional OWC at mean wave condition. The 55 deg inclined OWC recorded peak rotor power of 23.2 kW with an efficiency of 27.6% at the mean sea state. The peak power and efficiency at maximum sea state were 26.5 kW and 21.5%, respectively.

Effect of Oscillating Water Column Chamber Inclination on the Performance of a Savonius Rotor

2018 ◽  
Author(s):  
Deepak D. Prasad ◽  
Mohammed Rafiuddin Ahmed ◽  
Young-Ho Lee
Keyword(s):  
Water Column ◽  
Wave Energy ◽  
Hollow Structure ◽  
Flow Characteristics ◽  
Wave Crest ◽  
Oscillating Water Column ◽  
Sea State ◽  
Wave Condition ◽  
Improved Performance ◽  
Incident Waves

The global power potential of the waves that hit all the coasts worldwide has been estimated to be in the order of 1 TW. On an average, each wave crest transmits 10–50 kW/m of energy and this corresponds to 15 to 20 times more energy per meter than wind or solar energies. Wave energy is environmentally friendly and is the most consistent of all the intermittent sources. While wind, solar and wave are all intermittent, wave is the most consistent. Availability of waves is 90% compared to 30% for wind and solar energy. The oscillating water column (OWC) is the most investigated wave energy converter (WEC). OWC is a partially submerged hollow structure positioned, either vertically or at an angle. The bidirectional flow of air above the water column is used to drive a turbine. Majority of the OWC devices have chambers which are perpendicular to the incident waves. These conventional OWCs suffer severely from flow separation that occurs at the sharp corners of the chamber. In order to address this issue, researchers have proposed inclining the chamber at an angle with respect to the incident waves. This improves the flow characteristics. In addition to this, the flow in the chamber which ultimately decides the turbine performance, also increases. In the present study, the effect of OWC inclination on rotor performance was numerically studied using commercial computational fluid dynamics (CFD) code ANSYS CFX. The results highlight that the 55° inclined OWC showed improved performance when compared to the conventional OWC and current OWC. The maximum power for the inclined OWC was 13% higher than that recorded for the rotor in the current OWC and 28% than that recorded in the conventional OWC at mean wave condition. The 55° inclined OWC recorded peak rotor power of 23.2 kW which corresponded to an efficiency of 27.6% at the mean sea state. The peak power and efficiency at maximum sea state was 26.5 kW and 21.5% respectively. Higher oscillation was observed in the 55° inclined OWC. The combination of increased flow rate and energy in the flow lead to better performance of the 55° inclined OWC.

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.

Numerical Analysis of the Oscillating Water Column (OWC) Wave Energy Converter (WEC) Considering Different Incident Wave Height

2017 ◽  
Vol 370 ◽  
pp. 120-129
Author(s):  
Mateus das Neves Gomes ◽  
Eduardo Alves Amado ◽  
Elizaldo Domingues dos Santos ◽  
Liércio André Isoldi ◽  
Luiz Alberto Oliveira Rocha
Keyword(s):  
Water Column ◽  
Wave Height ◽  
Incident Wave ◽  
Wave Energy ◽  
Amplification Factor ◽  
Wave Energy Converter ◽  
Geometric Shape ◽  
Oscillating Water Column ◽  
Energy Converter ◽  
Incident Waves

The ocean wave energy conversion into electricity has been increasingly researched in the last years. There are several proposed converters, among them the Oscillating Water Column (OWC) device has been widely studied. The present paper presents a two-dimensional numerical investigation about the fluid dynamics behavior of an OWC Wave Energy Converter (WEC) into electrical energy. The main goal of this work was to numerically analyze the optimized geometric shape obtained in previous work under incident waves with different heights. To do so, the OWC geometric shape was kept constant while the incident wave height was varied. For the numerical solution it was used the Computational Fluid Dynamic (CFD) commercial code FLUENT®, based on the Finite Volume Method (FVM). The multiphasic Volume of Fluid (VOF) model was applied to tackle with the water-air interaction. The computational domain is represented by the OWC device coupled with the wave tank. This work allowed to check the influence of the incident wave height on the hydropneumatic power and the amplification factor of the OWC converter. It was possible to identify that the amplification factor increases as the wave period increases, thereby improving the OWC performance. It is worth to highlight that in the real phenomenon the incident waves on the OWC device have periods, lengths and height variables.

On the Efficiency of Oscillating Water Column (OWC) Devices in Converting Ocean Wave Energy to Electricity Under Weakly Nonlinear Waves

2012 ◽  
Author(s):  
Jean-Roch Nader ◽  
Song-Ping Zhu ◽  
Paul Cooper
Keyword(s):  
Water Column ◽  
Wave Energy ◽  
Ocean Wave ◽  
Recent Effort ◽  
Oscillating Water Column ◽  
Mean Power ◽  
Weakly Nonlinear ◽  
Ocean Wave Energy ◽  
Mean Power Output ◽  
Incident Waves

Oscillating Water Column (OWC) devices are regarded as one of the most promising systems developed to harness ocean wave energy. In this paper, we present some preliminary results of our most recent effort in the research of trying to improve the efficiency of OWCs with a focus on the comparison of incident waves being in the linear and weekly nonlinear regimes. As the results show, the counted-in nonlinearity at the second order could contribute to more than a 50% increase in the maximum mean power output.

scholarly journals Study on Shape Geometry of Floating Oscillating Water Column Wave Energy Converter for Low Heave Wave Condition

2020 ◽  
Vol 70 (2) ◽  
pp. 124-134
Author(s):  
Muhamad Jalani Aiman ◽  
Nur Izzati Ismail ◽  
Mohd Rashdan Saad ◽  
Yasutaka Imai ◽  
Shuichi Nagata ◽  
...  
Keyword(s):  
Water Column ◽  
Wave Energy ◽  
Wave Energy Converter ◽  
Oscillating Water Column ◽  
Energy Converter ◽  
Wave Condition

scholarly journals Numerical Evaluation of the Hydropneumatic Power of the Oscillating Water Column Wave Energy Converter Submitted to Regular and Irregular Waves

2021 ◽  
pp. 32-43
Author(s):  
Augusto Hack da Silva Koch ◽  
Maycon da Silveira Paiva ◽  
Caroline Barbosa Monteiro ◽  
Phelype Haron Oleinik ◽  
Liércio André Isoldi ◽  
...  
Keyword(s):  
Free Surface ◽  
Water Column ◽  
Wave Energy ◽  
Wave Energy Converter ◽  
Irregular Waves ◽  
Oscillating Water Column ◽  
Regular Waves ◽  
Energy Converter ◽  
Sea State ◽  
Electric Generator

The purpose of this study is to computationally analyze the hydropneumatic power available in the air duct of an Oscillating Water Column (OWC) Wave Energy Converter (WEC) device when subject to realistic sea state data (irregular waves) and when submitted to the regular waves representative of this sea state. The OWC WEC is mainly composed of a hydropneumatic chamber and an air duct where a turbine and electric generator are coupled. The chamber is open below the free surface while the duct is open to the atmosphere. The oscillating movement of the water-free surface inside the chamber causes the air to flow, moving the turbine and generating electricity. To execute this study, a bi-dimensional computational model was considered and numerical simulations of wave generation were carried out using ANSYS Fluent, which is a Computational Fluid Dynamics (CFD) software based on the Finite Volume Method (FVM). The Volume of Fluid (VOF) multi-phase model was applied in the treatment of the water-air interaction. To evaluate the average hydropneumatic power available in the duct, the static pressure, velocity, and air mass flow rate were monitored. The results were analyzed, showing that the available power is 250% greater when the device is subject to realistic irregular waves rather than subject to representative regular waves.

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