Expected Values of Wave Power Absorption Around the Japanese Islands Using OWC Types With Projecting Walls

2011 ◽  
Author(s):  
Tomoki Ikoma ◽  
Hiroyuki Osawa ◽  
Koichi Masuda ◽  
Hiisaaki Maeda
Keyword(s):  
Resonance Frequency ◽  
Performance Improvement ◽  
Standing Waves ◽  
Wave Power ◽  
Basic System ◽  
Oscillating Water Column ◽  
Power Absorption ◽  
Wide Range ◽  
Expected Values ◽  
Japanese Islands

This paper describes performance improvement of wave power absorption by using a new concept. Basic system proposed is an oscillating water column (OWC) type. An artificial harbor surrounded by projecting walls is installed. The type is called as PW-OWC in this paper. Standing waves occur in the artificial harbor, the absorbing device consequently has a resonance frequency differing from that of OWC. From the effect, the system is able to absorb wave power in very wide range of the wave frequency. From the experimental results, PW-OWC types are very good performance of wave power absorption comparing with conventional OWC types. In addition, the performance of the PW-OWC type is insensibility to the nozzle ratio of an orifice. The performance can be easily improved by installing the harbor part even if the performance of a base OWC device is not good. Finally, we investigate the expected values of acquirable wave power in not only a year but also every season. The expected values of PW-OWC types are greater than that of conventional OWC ones in seas around the Japanese islands.

Comparison of the performance of oscillating water column devices based on arrangements of water columns

2020 ◽  
Vol 14 (3) ◽  
pp. 7082-7093
Author(s):  
Jahirwan Ut Jasron ◽  
Sudjito Soeparmani ◽  
Lilis Yuliati ◽  
Djarot B. Darmadi
Keyword(s):  
Wave Propagation ◽  
Water Column ◽  
Water Depth ◽  
Graphical Form ◽  
Wave Power ◽  
Oscillating Water Column ◽  
Power Absorption ◽  
Water Columns ◽  
Single Column ◽  
Parallel Arrangement

The hydrodynamic performance of oscillating water column (OWC) depends on the depth of the water, the size of the water column and its arrangement, which affects the oscillation of the water surface in the column. An experimental method was conducted by testing 4 water depths with wave periods of 1-3 s. All data recorded by the sensor is then processed and presented in graphical form. The research focused on analyzing the difference in wave power absorption capabilities of the three geometric types of OWC based on arrangements of water columns. The OWC devices designed as single water column, the double water column in a series arrangement which was perpendicular to the direction of wave propagation, and double water column in which the arrangement of columns was parallel to the direction of wave propagation. This paper discussed several factors affecting the amount of power absorbed by the device. The factors are the ratio of water depth in its relation to wavelength (kh) and the inlet openings ratio (c/h) of the devices. The test results show that if the water depth increases in the range of kh 0.7 to 0.9, then the performance of the double chamber oscillating water column (DCOWC) device is better than the single chamber oscillating water column (SCOWC) device with maximum efficiency for the parallel arrangement 22,4%, series arrangement 20.8% and single column 20.7%. However, when referring to c/h, the maximum energy absorption efficiency for a single column is 27.7%, double column series arrangement is 23.2%, and double column parallel arrangement is 29.5%. Based on the results of the analysis, DCOWC devices in parallel arrangement showed the ability to absorb better wave power in a broader range of wave frequencies. The best wave of power absorption in the three testing models occurred in the wave period T = 1.3 seconds.

Wave Power Absorption Capability of a Multi-Resonant Double Chamber Oscillating Water Column Device

2014 ◽  
Vol 66 (2) ◽  
Author(s):  
R. Wilbert ◽  
V. Sundar ◽  
S. A. Sannasiraj
Keyword(s):  
Renewable Energy ◽  
Water Column ◽  
Wave Energy ◽  
Renewable Energy Sources ◽  
Absorption Capacity ◽  
Energy Sources ◽  
Wave Power ◽  
Oscillating Water Column ◽  
Power Absorption ◽  
Double Chamber

The reduction of the greenhouse gas emission generated through the usage of fossil fuel has become quite vital forcing us to look for alternative renewable energy sources. Among the renewable energy sources, ocean wave energy looks promising leading to worldwide involvement of researchers in the refinements of a number of the concepts. The conversion of energy available in ocean waves requires an interface device to interact with the kinetic and kinematic phenomena under the waves. These devices are known as wave energy converters (WECS). Among the available WECS oscillating water column (OWC) stands out as one of most promising concept. Though the OWC concept has emerged from laboratory model type to prototype plant, the high cost of production makes it less attractive in commercialism. This necessitates further refinement in the configuration of OWC concept to make it more attractive leading to economically competent. This can be achieved either by improving the efficiency or by integrating it with coastal protective breakwaters, viz., offshore detached breakwaters. The double chamber oscillating water is an innovative concept which can bring forth both efficiency and additional stability once it becomes an integral part of coastal breakwater. This system captures the high magnitude of dynamic pressure as the excitation force for the oscillation inside the OWC. The trajectory of flow pattern can provide additional vertical load which will enhance the stability factor of the breakwater. In this paper the wave power absorption capacity of a 1:20 scale physical model under varying regular wave characteristics is reported. In this insightful study the objective assessment over the hydrodynamic performance reveals the parametric influence over wave power absorption capacity of the device.

Wave-power absorption by an oscillating water column in a channel

1985 ◽  
Vol 158 ◽  
pp. 153-175 ◽  
Author(s):  
O. Malmo ◽  
A. Reitan
Keyword(s):  
Boundary Conditions ◽  
Water Column ◽  
Linear Theory ◽  
Wave Power ◽  
Oscillating Water Column ◽  
Power Absorption ◽  
Different Boundary Conditions

Wave-power absorption by an oscillating water column in a channel is studied within linear theory, and for different boundary conditions regarding the regions between the absorber and the channel walls. Particular attention is given to the effect of placing projecting sidewalls in front of the column.

scholarly journals Field-aligned chorus wave spectral power in Earth's outer radiation belt

2015 ◽  
Vol 33 (5) ◽  
pp. 583-597 ◽  
Author(s):  
H. Breuillard ◽  
O. Agapitov ◽  
A. Artemyev ◽  
E. A. Kronberg ◽  
S. E. Haaland ◽  
...  
Keyword(s):  
Pitch Angle ◽  
Radiation Belt ◽  
Spectral Power ◽  
Peak Frequency ◽  
Wave Power ◽  
Outer Radiation Belt ◽  
Substantial Impact ◽  
Wide Range ◽  
Frequency Variations ◽  
Chorus Wave

Abstract. Chorus-type whistler waves are one of the most intense electromagnetic waves generated naturally in the magnetosphere. These waves have a substantial impact on the radiation belt dynamics as they are thought to contribute to electron acceleration and losses into the ionosphere through resonant wave–particle interaction. Our study is devoted to the determination of chorus wave power distribution on frequency in a wide range of magnetic latitudes, from 0 to 40°. We use 10 years of magnetic and electric field wave power measured by STAFF-SA onboard Cluster spacecraft to model the initial (equatorial) chorus wave spectral power, as well as PEACE and RAPID measurements to model the properties of energetic electrons (~ 0.1–100 keV) in the outer radiation belt. The dependence of this distribution upon latitude obtained from Cluster STAFF-SA is then consistently reproduced along a certain L-shell range (4 ≤ L ≤ 6.5), employing WHAMP-based ray tracing simulations in hot plasma within a realistic inner magnetospheric model. We show here that, as latitude increases, the chorus peak frequency is globally shifted towards lower frequencies. Making use of our simulations, the peak frequency variations can be explained mostly in terms of wave damping and amplification, but also cross-L propagation. These results are in good agreement with previous studies of chorus wave spectral extent using data from different spacecraft (Cluster, POLAR and THEMIS). The chorus peak frequency variations are then employed to calculate the pitch angle and energy diffusion rates, resulting in more effective pitch angle electron scattering (electron lifetime is halved) but less effective acceleration. These peak frequency parameters can thus be used to improve the accuracy of diffusion coefficient calculations.

scholarly journals An approach to the low-resistance measurement

2013 ◽  
Vol 10 (2) ◽  
pp. 293-307
Author(s):  
Radojle Radetic ◽  
Marijana Pavlov-Kagadejev ◽  
Darko Brodic ◽  
Nikola Milivojevic
Keyword(s):  
Performance Improvement ◽  
Design Process ◽  
Comparison Method ◽  
Resistance Measurement ◽  
Functional Characteristics ◽  
The Real ◽  
Low Resistance ◽  
Wide Range ◽  
Resistor Measuring ◽  
The Way

The paper presents the real instrument functional characteristics and describes the way of practical solutions of its performance improvement. It presents the design process of the instrument made for resistance measuring. In order to achieve desired objectives, a great number of experiments have been carried out during the development. Basically, the comparison method has been applied. At first, it was intended for the small resistor measuring as a single range unit. Later, the device has been improved and upgraded for a wide range resistance measuring. Finally, some of the difficulties have been detected and explained as well. The paper contains solutions developed and applied for their overcoming.

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