Determination of the Optimal Buoy Shape for A Concept Wave Energy Converter to Harness Low Amplitude Sea Waves using Numerical Simulation (original) (raw)
Related papers
Buoy Analysis in a Point-Absorber Wave Energy Converter
IEEE Journal of Oceanic Engineering
In this paper, a single-body point absorber system is analyzed to enhance its power absorption performance. The wave energy converter consists of a single floating body coupled to a direct-drive power takeoff system placed on the seabed. The geometry of a cylindrical buoy with large draft is modified, obtaining a particular geometry that is used to enhance the power absorption of the wave converter at a given site and at a finite depth. A numerical analysis tool (NEMOH) is used to obtain the buoy's frequency-dependent hydrostatic parameters; in addition, the buoy's dimensions are parameterized to tune the natural frequency of the oscillating system toward the frequency of dominant incident waves, thus enhancing wave power absorption for a specific wave frequency range. Furthermore, the damping influence of the power takeoff system on the performance of the wave energy converter is also considered.
An Analysis Of The Performances Of Various Buoys As The Floats Of Wave Energy Converters
2016
The power generated by eight point absorber type wave energy converters each having a different buoy are calculated in order to investigate the performances of buoys in this study. The calculations are carried out by modeling three different sea states observed in two different locations in the Black Sea. The floats analyzed in this study have two basic geometries and four different draft/radius (d/r) ratios. The buoys possess the shapes of a semi-ellipsoid and a semi-elliptic paraboloid. Additionally, the draft/radius ratios range from 0.25 to 1 by an increment of 0.25. The radiation forces acting on the buoys due to the oscillatory motions of these bodies are evaluated by employing a 3D panel method along with a distribution of 3D pulsating sources in frequency domain. On the other hand, the wave forces acting on the buoys which are taken as the sum of Froude-Krylov forces and diffraction forces are calculated by using linear wave theory. Furthermore, the wave energy converters ar...
International Marine Energy Journal, 2021
A single-body point absorber system is analysed to improve its power absorption at a finite water depth. The proposed wave energy converter consists of a single floating body coupled to a direct-drive power take-off system placed on the seabed. The structure of a cylindrical buoy with large draft is changed by a single body composed of three structures rigidly coupled, reducing its volume and improving its frequency-dependent hydrostatic parameters that are obtained through a numerical analysis tool called NEMOH. The undamped natural frequency of the oscillating system is tuned to a specified wave period and the performance of the WEC system is obtained assuming a linear Power Take-Off system. In time domain, the performance of the WEC device is carried-out under a regular (sinusoidal) and irregular incident wave profile. Comparing the performance of the WEC system using the cylindrical and the proposed buoy outcomes that the system with the proposed buoy is able to absorb more ene...
Experimental Investigation of a Concept Wave Energy Converter for Harnessing Low Amplitude Sea Waves
Journal of Engineering Studies and Research
This paper presents the results from experimental validation of numerical simulation of a concept wave energy converter for low amplitude sea waves. The device was conceived to contain a wave amplifying device (WAD) to magnify the wave height of incident waves while point absorber buoy(s) efficiently harness the wave energy for electricity production. The validation results show that the optimum aperture angle for the WAD is 45±2 degree, and wave height magnification of 170% is possible. The optimal buoy shape for the device was confirmed as concave wedge buoy. The combination of the two in a single device shall make economical the harnessing of low amplitude waves.
Development and Testing of a Point Absorber Wave Energy Conversion
Volume 5: Ocean Space Utilization; Ocean Renewable Energy, 2011
Wave energy conversion as a means for small scale energy production is approaching commercial viability. This paper presents the undergoing development of a wave energy conversion device at the University of Hawaii at Manoa. The device is a three part point absorber with two buoys, one floating and absorbing incoming waves; the other maintaining tension on the third mechanism, the submerged power-takeoff unit. This design is discussed as three concept configurations for WEC construction. The analytical solution is developed, and the buoys response is computed due to a selected and analyzed sea-state.
Modeling of a point absorber buoy for sea wave energy conversion in Phan Thiet sea area
THE 1ST INTERNATIONAL CONFERENCE ON INNOVATIONS FOR COMPUTING, ENGINEERING AND MATERIALS, 2021: ICEM, 2021, 2021
In this paper, we investigated the feasibility of harvesting wave energy in Phan Thiet sea area. In Viet Nam seas, Phan Thiet sea area is the most suitable for exploiting wave energy. This paper studies exploiting sea wave energy by the point absorber method for Phan Thiet sea area. The point absorber is a popular harvesting sea wave energy method, it is suitable for areas with small wave energy as Phan Thiet sea area. This work build the floating body dynamics equation for point absorber buoy. By solving this equation, we have determined the efficiency of sea wave energy exploitation for Phan Thiet sea area. The result showed the wave energy in Phan Thiet sea area can be exploited effectively.
Heave Buoy Energy Converters; Simulation of Heave Buoy Response to Wave in Malaysian Water
Energy Procedia, 2014
Wave energy converter (WEC) designs are always discussed in order to find an optimum design to generate power. The power output from wave energy converters may be increase by controlling the oscillation in order to approach an optimum interaction between the WEC and the incident wave. However, in order to control the oscillation of the heave buoy, the wave profile and the device's response must be examined and fully understood. Analysis carried out by study heave buoys response on Malaysian water using MathCAD software. The results shows that the heave buoy give a good heave response with regards of the wave phase. In this particular area, it is estimated that the wave force can produce as much as 4x10 5 kW/m. From the response, the strategies to optimize power output can be proposed in order to maximize the active power to generate an optimum power output.
Experimental Investigation of Offshore Wave Buoy Performance
نشريه علمی پژوهشی مهندسی دريا, 2010
The important characteristic of sea waves is their high energy density, which is the highest among renewable energy sources. Having up to 2700 km. of shoreline, Iran has a great potential in construction of offshore wave buoys (hereafter called OWB). In this article a OWB model with the possibility of assembling different buoy configurations is introduced. The system is exposed to regular and irregular waves which are generated using wave maker in a 2D wave tank. Wave energy can be extracted from vertical oscillation of its floating buoy. The device is so designed as to operate in rotational (pitch) mode in addition to vertical (heave) motion. Some experiments are also conducted to demonstrate system performance. Experimental results in different conditions are presented and the effect of different buoy configurations on the system efficiency is studied. Numerical simulations that obtain the hydrodynamic coefficients and dynamic response (the Response Amplitude Operator or simply RAO) of each buoy in waves validate test results that the buoy with highest transfer function obtained in simulations has highest efficiency in power extraction. It is finally shown that the horizontal buoy is the most efficient configuration among other constructed buoys for extracting wave energy. The non-dimensional groups are studied and the output power of a full scale OWB is obtained based on similarity laws.
On the Optimization of Point Absorber Buoys
Journal of Marine Science and Engineering, 2014
A point absorbing wave energy converter (WEC) is a complicated dynamical system. A semi-submerged buoy drives a power takeoff device (PTO), which acts as a linear or non-linear damper of the WEC system. The buoy motion depends on the buoy geometry and dimensions, the mass of the moving parts of the system and on the damping force from the generator. The electromagnetic damping in the generator depends on both the generator specifications, the connected load and the buoy velocity. In this paper a velocity ratio has been used to study how the geometric parameters buoy draft and radius, assuming constant generator damping coefficient, affects the motion and the energy absorption of a WEC. It have been concluded that an optimal buoy geometry can be identified for a specific generator damping. The simulated WEC performance have been compared with experimental values from two WECs with similar generators but different buoys. Conclusions have been drawn about their behaviour.