Effects of a Submerged Vertical Plate and a Wave Energy Absorption Air-chamber to a Hydroelastic Response Reduction of VLFS

2006 ◽  
Author(s):  
T. Ikoma ◽  
K. Masuda ◽  
H. Maeda ◽  
Chang-Kyu Rheem ◽  
M. Arita
Keyword(s):  
Energy Absorption ◽  
Wave Energy ◽  
Vertical Plate ◽  
Air Chamber ◽  
Hydroelastic Response

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

Hydroelastic Behavior of Air-Supported Flexible Floating Structures

2002 ◽  
Author(s):  
Tomoki Ikoma ◽  
Koichi Masuda ◽  
Hisaaki Maeda ◽  
Chang-Kyu Rheem
Keyword(s):  
Pressure Distribution ◽  
Energy Absorption ◽  
Elastic Deformation ◽  
Wave Energy ◽  
Distribution Method ◽  
Elastic Deformations ◽  
Floating Structures ◽  
Air Chamber ◽  
Air Cushion ◽  
Offshore Field

A pontoon type very large floating structure has elastic deformations in ocean waves. The deformation is larger than that of a semi-submergible type one. Thus, a pontoon type one will be installed to tranquil shallow water field enclosed by breakwaters. Moreover, a semi-submergible one will be applicable to development at offshore field. The authors has developed a pontoon type VLFS with an OWC (oscillating water column) type wave energy absorption system. This can be install to offshore field being deep water relatively. Such VLFS can reduce not only the elastic deformation but also the wave drifting forces. However, it is very difficult to reduce the wave drifting forces effectively because an effect of the reduction depends on the wave energy absorption. Therefore, the authors propose an air supported type VLFS. This idea has been already proposed. However, it wasn’t handled a flexible structure. Such an air-supported structure makes to transmit many waves. Therefore, the wave drifting forces may not increase. In addition, the elastic deformation may decrease because pressure distribution due to the incident waves becomes constant at the bottom of the structure, i.e. the pressure is constant in a same air chamber. We develop the program code for the analysis of the hydrodynamic forces on the VLFS with the air cushion. The potential flow theory is applied and the pressure distribution method is used to the analysis of the wave pressures. The zero-draft is assumed in this method. The pressure and volume change of the air cushion are linearized. In this paper, basic characteristics of the elastic deformations of the air-supported flexible floating structures are investigated. We confirm the effectiveness, and discuss behaviors of the water waves in air chamber areas.

scholarly journals Hydroelastic Response of a Flexible Submerged Porous Plate for Wave Energy Absorption

2020 ◽  
Vol 8 (9) ◽  
pp. 698
Author(s):  
Sarat Chandra Mohapatra ◽  
C. Guedes Soares
Keyword(s):  
Porous Structure ◽  
Energy Absorption ◽  
Wave Energy ◽  
Porous Plate ◽  
Expansion Method ◽  
Finite Depth ◽  
Design Parameters ◽  
Coastal Protection ◽  
Expansion Formula ◽  
Hydroelastic Response

The application of flexible horizontal porous structure has a significant impact on the design of breakwaters and wave energy absorption devices for coastal protection and wave energy extraction, respectively. This type of structure is more economical compared to a rigid type structure. Therefore, the hydroelastic response of the flexible porous structure can be investigated to widen the influence of structural deformations in design parameters. This paper presents a generalized expansion formula for the said problem based on Green’s function in the water of finite depth (FD) and infinite depth (ID). The series form of the velocity potentials for the wave-maker problem is also derived using Green’s second identity. The derived expansion formula is applied to a real physical problem and the analytical solution is obtained utilizing a matched eigenfunction expansion method under velocity potential decompositions. The convergence study of the series solution is checked. The present results and the published experimental datasets, as well as analysis, are compared. The effect of design parameters on the hydroelastic response of the submerged flexible porous plate is analyzed. It is observed that the analysis of the results will be useful for gaining insight into how to design a wave energy absorption device.

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.

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

Characteristics of Hydrodynamics and Generating Output of the Offshore Floating Wave Energy Device “Mighty Whale”

2013 ◽  
Vol 135 (1) ◽  
Author(s):  
Hiroyuki Osawa ◽  
Tsuyoshi Miyazaki ◽  
Shogo Miyajima
Keyword(s):  
Energy Absorption ◽  
Output Power ◽  
Wave Energy ◽  
Power Device ◽  
Hydrodynamic Characteristics ◽  
Wave Power ◽  
Water Tank ◽  
Power Devices ◽  
Turbine Generator ◽  
Generator System

In this paper, a new numerical calculation method is presented; it was developed for the analysis of the hydrodynamic characteristics of a floating, oscillating water column (OWC) type wave power device. The method is examined by comparing results calculated with the method with results of water tank experiments. The examination was concerned with the determination of hydrodynamic coefficients, characteristics of air pressure and water level in an air chamber, and characteristics of hull motion and wave energy absorption. The calculated results agreed with the results of water tank tests; the method presented adequately estimated the hydrodynamic characteristics of the floating OWC type wave power device, including the wave energy absorption effects. An estimation method is presented for the output power of a turbine-generator system. The method was developed for the design of the “Mighty Whale” turbine-generator system. Moreover, the method was assessed by comparing predictions with open sea test results. The mean value of the output power was estimated reasonably well. In conclusion, the estimation methods presented are useful for the design of floating OWC wave power devices. Such tools are useful for the designer interested in developing optimal wave power devices.

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