Frequency Response Analysis of an Ocean Wave Energy Converter

1983 ◽  
Vol 105 (1) ◽  
pp. 30-38 ◽  
Author(s):  
M. Masubuchi ◽  
R. Kawatani
Keyword(s):  
Wave Energy ◽  
Wave Train ◽  
Mechanical Energy ◽  
Energy Conversion Efficiency ◽  
Wave Energy Converter ◽  
Response Analysis ◽  
Floating Bodies ◽  
Energy Converter ◽  
Ocean Wave Energy ◽  
Basic Equations

A theoretical analysis is presented for the dynamic behavior and energy conversion efficiency of a wave energy converter which is oscillating and absorbing power in an incident sinusoidal wave train. The energy converter consists of two floating bodies which have different configuration and are connected by a rigid link. Basic equations governing the floating bodies contained in the energy converter are obtained by assuming two dimensional motions and by considering the interactions between the two bodies and hydrodynamic and damping forces, and they have been solved numerically by using Lewis form as the configuration of the floating bodies. Energy absorption is assumed to be proportional to the square of the relative velocity between the oscillating body and the connecting link. It is shown that nearly 100 percent of wave energy is converted into mechanical energy in a wide frequency band.

scholarly journals Effective Mooring Rope Tension in Mechanical and Hydraulic Power Take-Off of Wave Energy Converter

2021 ◽  
Vol 13 (17) ◽  
pp. 9803
Author(s):  
Ji Woo Nam ◽  
Yong Jun Sung ◽  
Seong Wook Cho
Keyword(s):  
Energy Conversion ◽  
Wave Energy ◽  
Mechanical Energy ◽  
Electrical Energy ◽  
Energy Conversion Efficiency ◽  
Wave Energy Converter ◽  
Hydraulic Motor ◽  
Energy Converter ◽  
The Individual ◽  
Conversion Efficiencies

The InWave wave energy converter (WEC), which is three-tether WEC type, absorbs wave energy via moored cylindrical buoys with three ropes connected to a terrestrial power take-off (PTO) through a subsea pulley. In this study, a simulation study was conducted to select a suitable PTO when designing a three-tether WEC. The mechanical PTO transfers energy from the buoy to the generator using a gearbox, whereas the hydraulic PTO uses a hydraulic pump, an accumulator, and a hydraulic motor to convert mechanical energy into electrical energy. The hydraulic PTO has a lower energy conversion efficiency than that of the mechanical PTO owing to losses resulting from pipe friction and the individual efficiencies of the hydraulic pumps and motors. However, the efficiencies mentioned above are not the efficiency of the whole system. The efficiency of the whole system should be analyzed considering the tension of the rope and the efficiency of the generator. In this study, the energy conversion efficiencies of the InWave WEC installed the mechanical and hydraulic PTO devices are compared, and their behaviors are analyzed through numerical simulations. The mechanics of mechanical and hydraulic PTO applied to InWave are mathematically expressed, and the issues of the elements constituting the PTO are explained. Finally, factors to consider for PTO selection are presented.

A Study on Development of the Performance Analysis Method of the Floating OWC-WEC Using the MPS Method

2015 ◽  
Author(s):  
Yutaro Sasahara ◽  
Mitsuhiro Masuda ◽  
Kiyokazu Minami
Keyword(s):  
Wave Energy ◽  
Two Phase Flow ◽  
Wave Energy Converter ◽  
Response Analysis ◽  
Phase Flow ◽  
Energy Converter ◽  
Wave Impact ◽  
Two Phase ◽  
Mps Method ◽  
Type Wave

When concrete examination towards utilization is needed, it is necessary to estimate the safety and the performance of a floating Oscillation Water Column (OWC)-type wave energy converter under abnormal oceanographic phenomenon such as large waves, wave impact force, deck wetness and complex motion of mooring system. Therefore, to choose a proper numerical method is important. This present paper describes a fundamental study about estimation of safety and performance of floating OWC-type wave energy converter using the two-phase flow MPS method. In this research, firstly, new algorithm is installed in order to solve problems of the two-phase flow MPS method. Secondly, applicability to an response analysis of a wharf installation type OWC-WEC of the improved MPS method is examined by wave pressure acting to the OWC-WEC and response in the air chamber of the OWC-WEC.

scholarly journals Loads on a Point-Absorber Wave Energy Converter in Regular and Focused Extreme Wave Events

2020 ◽  
Author(s):  
Eirini Katsidoniotaki ◽  
Edward Ransley ◽  
Scott Brown ◽  
Johannes Palm ◽  
Jens Engström ◽  
...  
Keyword(s):  
Wave Energy ◽  
Wave Train ◽  
Offshore Structures ◽  
Wave Energy Converter ◽  
Extreme Waves ◽  
Extreme Wave ◽  
Energy Converter ◽  
Point Absorber ◽  
Wave Energy Converters ◽  
Extreme Loads

Abstract Accurate modeling and prediction of extreme loads for survivability is of crucial importance if wave energy is to become commercially viable. The fundamental differences in scale and dynamics from traditional offshore structures, as well as the fact that wave energy has not converged around one or a few technologies, implies that it is still an open question how the extreme loads should be modeled. In recent years, several methods to model wave energy converters in extreme waves have been developed, but it is not yet clear how the different methods compare. The purpose of this work is the comparison of two widely used approaches when studying the response of a point-absorber wave energy converter in extreme waves, using the open-source CFD software OpenFOAM. The equivalent design-waves are generated both as equivalent regular waves and as focused waves defined using NewWave theory. Our results show that the different extreme wave modeling methods produce different dynamics and extreme forces acting on the system. It is concluded that for the investigation of point-absorber response in extreme wave conditions, the wave train dynamics and the motion history of the buoy are of high importance for the resulting buoy response and mooring forces.

scholarly journals Design and simulation of point absorber wave energy converter

2021 ◽  
Vol 321 ◽  
pp. 03003
Author(s):  
Devesh Singh ◽  
Anoop Singh ◽  
Akshoy Ranjan Paul ◽  
Abdus Samad
Keyword(s):  
Energy Harvesting ◽  
Wave Energy ◽  
Wave Energy Converter ◽  
Response Analysis ◽  
Ocean Energy ◽  
Energy Converter ◽  
Point Absorber ◽  
Time Response Analysis ◽  
Floating System ◽  
Energy Harvesting System

The paper aims to design and simulation of a wave energy harvesting system commonly known as point absorber for Ennore port located in the coastal area of Chennai, India. The geographical condition of India, which is surrounded by the three sides with seas and ocean, has enormous opportunity for power production through wave energy harvesting system. The wave energy converter device is a two-body floating system and its both parts are connected by power take-off unit which acts as spring mass damper system. In this paper, the hydrodynamic diffraction, stability analysis, frequency, and time response analysis is carried out on ansys-aqwa. The numerical results are compared with the results obtained from the similar experiments for validation of CFD solver. Effects of the properties featuring wave characteristics including wave height and wave period of Ennore port on the energy conversion, Froude-Krylov and diffraction force, response amplitude operator (RAO) are studied. Based on the study, float diameter, draft, geometry, and varying damping coefficient for power generation are optimized. Finally, the optimally designed point absorber is simulated as per Indian ocean energy harvesting standard and mass of the system, heave dimension, diffraction forces, and pressure variations are computed.

scholarly journals Validation of a CFD-based numerical wave tank model for the power production assessment of the wavestar ocean wave energy converter

2020 ◽  
Vol 146 ◽  
pp. 2499-2516 ◽  
Author(s):  
Christian Windt ◽  
Josh Davidson ◽  
Edward J. Ransley ◽  
Deborah Greaves ◽  
Morten Jakobsen ◽  
...  
Keyword(s):  
Wave Energy ◽  
Power Production ◽  
Wave Energy Converter ◽  
Ocean Wave ◽  
Numerical Wave Tank ◽  
Energy Converter ◽  
Tank Model ◽  
Wave Tank ◽  
Ocean Wave Energy ◽  
Numerical Wave
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