Tag Archives: Component Development

Shape design and numerical analysis on a 1 MW tidal current turbine for the south-western coast of Korea


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Patrick Mark Singh and Young-Do Choi, Renewable Energy – August 2014

Abstract

The study concentrates on the shape design and numerical analysis of a 1 MW horizontal axis tidal current turbine (HATCT), which can be applied near the southwest regions of Korea. On the basis of actual tidal current conditions of south-western region of Korea, configuration design of 1 MW class turbine rotor blade is carried out by blade element momentum theory (BEMT). The hydrodynamic performance including the lift and drag forces, is conducted with the variation of the angle of attack using an open source code of X-Foil. The optimized blade geometry is used for Computational Fluid Dynamics (CFD) analysis with hexahedral numerical grids. This study focuses on developing a new hydrofoil and designing a blade with relatively shorter chord length in contrast to a typical TCT blade. Therefore, after a thorough study of two common hydrofoils, (S814 and DU-91-W2-250, which show good performance for rough conditions), a new hydrofoil, MNU26, is developed. The new hydrofoil has a 26% thickness that can be applied throughout the blade length, giving good structural strength. Power coefficient, pressure and velocity distributions are investigated according to Tip Speed Ratio by CFD analysis. As cavitation analysis is also an important part of the study, it is investigated for all the three hydrofoils. Due to the shorter chord length of the new turbine blade in contrast to a typical TCT blade design, a Fluid Structure Interaction (FSI) analysis is also done. Concrete conclusions have been made after comparing the three hydrofoils, considering their performance, efficiency, occurrence of cavitation and structural feasibility.

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Submerged Transmission in Wave Energy Converters: Full Scale In-Situ Experimental Measurements


E Strömstedt – Uppsala University Doctoral Thesis, August 2012

Abstract
Different wave power technologies are in development around the world in different stages of prototype testing. So far only a few devices have been deployed offshore at full scale for extended periods of time. Little data is published about how these different devices perform.This thesis presents results from experiments with the full-scale offshore wave energy converters at the Lysekil research site on the Swedish west coast. The theories, experiments, measurements, performance evaluations and developments of the submerged transmission in the direct driven permanent magnet linear generator are in focus. The reciprocating submerged transmission fulfills the purpose of transmitting the absorbed mechanical wave energy through the capsule wall into the generator, while preventing the seawater from entering the capsule and reducing the life time of the converter. Continue reading

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Experimental wave termination in a 2D wave tunnel using a cycloidal wave energy converter


SG Siegel, C Fagley, S Nowlin – Applied Ocean Research, October 2012

Abstract

A lift based cycloidal wave energy converter (CycWEC) is investigated in a 1:300 scale two-dimensional wave flume experiment. This type of wave energy converter consists of a shaft with one or more hydrofoils attached eccentrically at a radius. The main shaft is aligned parallel to the wave crests and submerged at a fixed depth. The operation of the CycWEC both as a wave generator as well as a wave-to-shaft energy converter interacting with straight crested waves is demonstrated. The geometry of the converter is shown to be suitable for wave termination of straight crested harmonic and irregular waves. The impact of design parameters such as device size, submergence depth, and number of hydrofoils on the performance of the converter is shown. For optimal parameter choices, experimental results demonstrate energy extraction efficiencies of more than 95% of the incoming wave energy. This is achieved using feedback control to synchronize the rotation of the CycWEC to the incoming wave, and adjusting the blade pitch angle in proportion to the wave height. Due to the ability of the CycWEC to generate a single sided wave with few harmonic waves, little energy is lost to waves radiating in the up-wave and down-wave directions.

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Coated High Strength Fibers (Patent)


R Bosman, G Aben, H Schneiders – US Patent 20,120,198,808, August 2012

Abstract
The invention relates to a high strength fibers comprising a coating of cross-linked silicone polymer, and ropes made thereof. The fibers are preferably high performance polyethylene (HPPE) fibers. The coating comprising a cross-linked silicone polymer is made from a coating composition comprising a cross-linkable silicone polymer. The rope shows markedly improved service life performance in bending applications such as cyclic bend-over-sheave applications. The invention also relates to the use of a cross-linked silicone polymer in a rope for an improvement of bend fatigue resistance.

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Reliability analysis for hydrokinetic turbine blades


Z Hu, X Du – Renewable Energy, December 2012

Abstract
Reliability is an important element in the performance of hydrokinetic turbines. It is also a driving factor of the system lifetime cost. In this paper, we perform time-dependent reliability analysis for the blades of a river-based horizontal-axis hydrokinetic turbine. Based on the stochastic representation of the monthly river velocity and material strength, a limit-state function is established with the classical blade element momentum method. In the limit-state function, a failure is defined as the event when the flapwise bending moment exceeds the allowable moment that corresponds to the ultimate strength of the material. The upcrossing rate method is employed to calculate the time-dependent reliability of the hydrokinetic turbine blade over its design life period. The results indicate that setting a proper cut-out river velocity is important for the reliability of the hydrokinetic turbine blade.

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Wave Energy Systems – Final Report


Wells, B., I. Sultan, A. Wiest, P. Maloney, S. Baboolal, C. Gestewitz, and M. Suarez – Florida Institute of Technology, Project Report, July 2012

Abstract

The Wave Energy Team at Florida Institute of Technology aims to create an interchangeable, environmentally friendly power take off unit which can perform efficiently in a variety of wave energy harvesting devices. Secondary objectives include testing and proving of existing structural and mechanical components previously developed by ocean engineering and mechanical engineering students.

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A study of diffuser angle effect on ducted water current turbine performance using CFD


P Khunthongjan, A Janyalertadun – Songklanakarin Journal of Science and Technology February 2012

Abstract
The water current has used as the energy resource for long time however its velocity is very low therefore there are not found in wide range of uses. This study purposes accelerate water velocity by installing diffuser. The problems were analyzed by one dimension analysis and computational fluid dynamics (CFD); the domain covers the diffuser and turbine which substituted by porous jump condition is install inside. The flow was identified as axisymmetric steady flow, the inlet boundary is identified as uniform flow, all simulation use the same size of diffuser, only the diffuser angles are vary. The results show that velocities of water current in diffuser are increase when the diffuser angle are widen. The angle of diffuser is 20°, the velocity is increase to 1.96 times, compared to free stream velocity. If the angle was about 0-20° and 50-70° the force toward diffuser became high instantly; whereas the force toward the rotor will be still and the maximum rate of diffuser augmentation possibly was 3.62 and rotor power coefficient was 2.14.

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Multi-arrayed tidal current energy farm and the integration method of the power transportation


CH Jo, KH Lee, JH Lee, C Nichita – 2012 International Symposium on Power Electronics, Electrical Drives, Automation, and Motion, June  2012

Abstract
Ocean energy resources are attractive renewable supply options for Korea being surround by ocean. Also having very strong tidal current speeds, there are many suitable sites for the application of TCP (Tidal Current Power) on the west and south coastal region in Korea with the maximum current speed of up to 6.5m/s. Not like other renewable energy sources, TCP is the high reliable and predictable and continuous energy source as the current pattern and speed can be predicted throughout the year. Since the large scale tidal current farm consists of many units of the turbine devices, the interaction effect is very important in power production. Also the power integration method in ocean energy has of very important issue. In this paper, the interaction effect and the power connection methods for each turbine unit and the integration method for 200MW tidal current farm are conceptually introduced with the offshore power integration platform

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Wave energy converter control by wave prediction and dynamic programming


G Li, G Weiss, M Mueller, S Townley, MR Belmont – Renewable Energy, June 2012

Highlights
► We investigate constrained optimal control of sea wave energy converters. ► The objective is to maximize energy take-off while minimizing the risk of damage. ► The optimal control problem is analyzed using Pontryagin’s minimum principle. ► Dynamic programming is employed to resolve the on-line optimization problem. ► Simulation result shows at least a two-fold increase in energy output.

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Synchronized control of cross-flow-water-turbine-based twin towers


M Vallet, I Munteanu, AI Bratcu, S Bacha, D Roye – Renewable Energy, June 2012

Highlights
► A system composed of cross-flow-water-turbine-based twin vertical towers is studied. ► The angular position synchronization of the two towers is ensured by control action. ► This approach is similar to the phase-locked loop techniques used in electronics. ► Real-time experiments on a power hardware-in-the-loop simulator have been carried out. ► The results sustain the reliability and effectiveness of the approach.

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