scholarly journals Wave energy absorption by a floating air bag

2016 ◽  
Vol 812 ◽  
pp. 294-320 ◽  
Author(s):  
A. Kurniawan ◽  
J. R. Chaplin ◽  
D. M. Greaves ◽  
M. Hann
Keyword(s):  
Dynamic Response ◽  
Energy Absorption ◽  
Wave Energy ◽  
Volume Ratio ◽  
Phase Control ◽  
Small Scale ◽  
Air Volume ◽  
Air Bag ◽  
The Waves ◽  
Shape And Size

A floating air bag, ballasted in water, expands and contracts as it heaves under wave action. Connecting the bag to a secondary volume via a turbine transforms the bag into a device capable of generating useful energy from the waves. Small-scale measurements of the device reveal some interesting properties, which are successfully predicted numerically. Owing to its compressibility, the device can have a heave resonance period longer than that of a rigid device of the same shape and size, without any phase control. Furthermore, varying the amount of air in the bag is found to change its shape and hence its dynamic response, while varying the turbine damping or the air volume ratio changes the dynamic response without changing the shape.

scholarly journals A broadbanded pressure differential wave energy converter based on dielectric elastomer generators

2021 ◽  
Author(s):  
Michele Righi ◽  
Giacomo Moretti ◽  
David Forehand ◽  
Lorenzo Agostini ◽  
Rocco Vertechy ◽  
...  
Keyword(s):  
Wave Energy ◽  
Large Deformations ◽  
Dielectric Elastomer ◽  
Wave Energy Converter ◽  
Pressure Differential ◽  
Design Stage ◽  
Small Scale ◽  
Energy Converter ◽  
Wide Range ◽  
The Waves

AbstractDielectric elastomer generators (DEGs) are a promising option for the implementation of affordable and reliable sea wave energy converters (WECs), as they show considerable promise in replacing expensive and inefficient power take-off systems with cheap direct-drive generators. This paper introduces a concept of a pressure differential wave energy converter, equipped with a DEG power take-off operating in direct contact with sea water. The device consists of a closed submerged air chamber, with a fluid-directing duct and a deformable DEG power take-off mounted on its top surface. The DEG is cyclically deformed by wave-induced pressure, thus acting both as the power take-off and as a deformable interface with the waves. This layout allows the partial balancing of the stiffness due to the DEG’s elasticity with the negative hydrostatic stiffness contribution associated with the displacement of the water column on top of the DEG. This feature makes it possible to design devices in which the DEG exhibits large deformations over a wide range of excitation frequencies, potentially achieving large power capture in a wide range of sea states. We propose a modelling approach for the system that relies on potential-flow theory and electroelasticity theory. This model makes it possible to predict the system dynamic response in different operational conditions and it is computationally efficient to perform iterative and repeated simulations, which are required at the design stage of a new WEC. We performed tests on a small-scale prototype in a wave tank with the aim of investigating the fluid–structure interaction between the DEG membrane and the waves in dynamical conditions and validating the numerical model. The experimental results proved that the device exhibits large deformations of the DEG power take-off over a broad range of monochromatic and panchromatic sea states. The proposed model demonstrates good agreement with the experimental data, hence proving its suitability and effectiveness as a design and prediction tool.

Wave Energy Hyperbaric Device for Electricity Production

2007 ◽  
Author(s):  
Segen F. Estefen ◽  
Paulo Roberto da Costa ◽  
Eliab Ricarte ◽  
Marcelo M. Pinheiro
Keyword(s):  
Power Generation ◽  
Wave Energy ◽  
Experimental Results ◽  
Electricity Production ◽  
Scale Model ◽  
Small Scale ◽  
Regular Waves ◽  
Hyperbaric Chamber ◽  
Small Scale Model

Wave energy is a renewable and non-polluting source and its use is being studied in different countries. The paper presents an overview on the harnessing of energy from waves and the activities associated with setting up a plant for extracting energy from waves in Port of Pecem, on the coast of Ceara State, Brazil. The technology employed is based on storing water under pressure in a hyperbaric chamber, from which a controlled jet of water drives a standard turbine. The wave resource at the proposed location is presented in terms of statistics data obtained from previous monitoring. The device components are described and small scale model tested under regular waves representatives of the installation region. Based on the experimental results values of prescribed pressures are identified in order to optimize the power generation.

Small scale experimental study of the dynamic response of a tension leg platform wind turbine

2014 ◽  
Vol 6 (5) ◽  
pp. 053108 ◽  
Author(s):  
Anders Mandrup Hansen ◽  
Robert Laugesen ◽  
Henrik Bredmose ◽  
Robert Mikkelsen ◽  
Nikolaos Psichogios
Keyword(s):  
Experimental Study ◽  
Dynamic Response ◽  
Wind Turbine ◽  
Small Scale ◽  
Tension Leg Platform

I-1 Wave energy absorption characteristics of circular air chamber for use of light beacon

1985 ◽  
Vol 12 (6) ◽  
pp. 554-555 ◽  
Author(s):  
Reisaku Inoue ◽  
Masami Iwai ◽  
Masaru Yahagi ◽  
Tetsuo Yamazaki
Keyword(s):  
Energy Absorption ◽  
Wave Energy ◽  
Air Chamber ◽  
Absorption Characteristics

Fluid Flow and Heat Transfer of Liquid Sodium in Small-Scale Heat Sinks With Different Geometries

2021 ◽  
Author(s):  
Mahyar Pourghasemi ◽  
Nima Fathi
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Cross Sections ◽  
Heat Sink ◽  
Volume Ratio ◽  
Heat Sinks ◽  
Liquid Sodium ◽  
Small Scale ◽  
Nusselt Numbers ◽  
The Difference

Abstract 3-D numerical simulations are performed to investigate liquid sodium (Na) flow and the heat transfer within miniature heat sinks with different geometries and hydraulic diameters of less than 5 mm. Two different straight small-scale heat sinks with rectangular and triangular cross-sections are studied in the laminar flow with the Reynolds number up to 1900. The local and average Nusselt numbers are obtained and compared against eachother. At the same surface area to volume ratio, rectangular minichannel heat sink leads to almost 280% higher convective heat transfer rate in comparison with triangular heat sink. It is observed that the difference between thermal efficiencies of rectangular and triangular minichannel heat sinks was independent of flow Reynolds number.

scholarly journals CFD-Based Determination of the Optimal Blowing and Suction Air Volume Ratio of Dual-Radial Swirl Shielding Ventilation in a Fully Mechanized Excavation Face

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Kuan Wu ◽  
Shiliang Shi ◽  
Yijie Shi ◽  
Yong Chen
Keyword(s):  
Ventilation System ◽  
Volume Ratio ◽  
Simulation Method ◽  
Dust Concentration ◽  
Dust Control ◽  
Underground Mines ◽  
Physical And Mental Health ◽  
Control Effect ◽  
Air Curtain ◽  
Air Volume

Dust is one of the main pollutants in coal mines, which seriously affects the physical and mental health of workers, as well as the safe production in underground mines. Dual-radial swirl shielding ventilation is a new ventilation method for a fully mechanized excavation face and can effectively reduce the dust concentration in the underground. The dust control effect of dual-radial swirl shielding ventilation is mainly affected by the thickness and integrity of the shielding air curtain, as well as the disturbance of the flow field near the air curtain. By changing the blowing and suction air volume ratio of the air duct, the strength of the radial air curtain can be improved, and the dust control effect of the dual-radial swirl shielding ventilation system can be effectively improved. In order to determine the optimal operating parameters of the dual-radial swirl shielding ventilation system, a numerical simulation method was used to conduct an in-depth study on the blowing and suction air volume ratio of the system. The results showed that when the blowing and suction air volume ratio of the air duct was 1.5, the radial air curtain had the highest strength. Under this condition, the dust concentration at the driver’s position of the roadheader was the lowest, and the dual-radial swirl shielding ventilation system can achieve an ideal dust control effect.

Acoustic wave energy absorption and distributed heat sources upon an acoustic impact on media

2016 ◽  
Vol 54 (1) ◽  
pp. 56-61 ◽  
Author(s):  
G. R. Izmailova ◽  
L. A. Kovaleva ◽  
N. M. Nasyrov
Keyword(s):  
Acoustic Wave ◽  
Energy Absorption ◽  
Wave Energy ◽  
Heat Sources ◽  
Acoustic Impact
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