Wave power

About: Wave power is a research topic. Over the lifetime, 2671 publications have been published within this topic receiving 41439 citations. The topic is also known as: wind wave energy & sea wave energy.

Numerical simulation of wave energy converters using Eulerian and Lagrangian CFD methods

Abstract: During the last years many concepts of wave energy converters (WEC) have been proposed. All are designed to generate energy at competitive economic rates in average sea states and also to survive extreme wave conditions. Due to the complexity of most offshore wave energy devices and their motion response in different sea states, physical tank tests are common practice for WEC design. Full scale tests are also necessary, but are expensive and only considered once the design has been optimised. Computational Fluid Dynamics (CFD) is now recognised as an important complement to traditional physical testing techniques in offshore engineering. Once properly calibrated and validated to the problem, CFD offers a high density of test data and results in a reasonable timescale to assist with design changes and improvements to the device. Within the EPSRC funded research project "Extreme Wave Loading on Offshore Wave Energy Devices: a Hierarchical Team Approach" the two WECs Pelamis and the Manchester Bobber are investigated using different Eulerian and Lagrangian CFD techniques. Both devices float on the water surface and generate the electricity from the motion of the waves. Pelamis' overall movement is limited due to the mooring system, but the individual segments are allowed to move in 6 degrees of freedom and interact with the waves and the adjacent segments. The dynamics of the Manchester Bobber comprise the nominally vertical motion of the floats, which are arranged in an array, and the highly complex interactions between the floats and the waves. Two test cases leading towards simulation of the full dynamics of Pelamis and the Manchester Bobber have been modelled using different CFD techniques. The problems involve the interaction between regular waves and fixed horizontal cylinders of different levels of submergence. Results are compared with experimental data to calibrate the CFD codes. Furthermore, results for the fluid-structure interaction of an oscillating cone on the water surface are presented. The complexity of this problem is rather high, as it involves rigid body motion of an axisymmetric body. The motion is not linear, but is generated as a Gaussian focused wave packet. Complex jet-effects occur at the intersection of water and body surface. These and the forces on the structure are discussed. Four different CFD codes are applied to simulate the test cases: Smoothed Particle Hydrodynamics, a Cartesian Cut Cell method based on an artificial compressibility method with shock capturing for the interface, and two pressure-based Navier-Stokes codes, one using a Finite Volume and the other a control volume based Finite Element approach. ?? 2010 by The International Society of Offshore and Polar Engineers (ISOPE).

Combined type green energy resource ship

Abstract: The utility model relates a combined type green energy resource ship, in particular to a combined type green energy resource ship which comprehensively adopts wind energy source, solar energy source and sea wave energy source. Wind power systems (4) are respectively arranged at the head and the tail of a ship hull (1); a solar power system (3) is arranged on the outer surface of the central cabin of the ship hull (1); sea wave power systems (3) are arranged in the water lines on the both sides of the ship hull (1); and an intelligent controller, a storage battery, a converter, an actuating motor and other loads are arranged inside the ship hull (1). By comprehensively gathering wind energy source, solar energy source and sea wave energy source, the energy can be supplied to the energy resource ship, and when the energy is insufficient, the storage battery of the ship can be charged with commercial power, to supply energy to the ship.

Design and Analysis of a Novel Modular Linear Double-Stator Biased Flux Machine

Abstract: In this paper, a novel modular linear double-stator biased flux (LDSBF) machine is proposed for wave power generation. The operation principle based on flux path analysis is presented. And stator/rotor pole number combinations are discussed by using coil flux analysis. The modular LDSBF machine has better flux path distribution than its counterpart, namely, linear biased flux permanent magnetic machine. More than that, the topology of the modular LDSBF machine makes it feasible to modular design and easy assembly. The electromagnetic characteristics of four types of linear machines are analyzed and compared by using time-stepping finite-element method. The comparative study shows that modular LDSBF machine with improved performance is a good potential design for wave power generation.

Introducing Wave Regeneration by Wind in a Mild-Slope Wave Propagation Model MILDwave to Investigate the Wake Effects in the Lee of a Farm of Wave Energy Converters

Abstract: The increasing energy demand, the need to reduce greenhouse gas emissions and the shrinking reserves of fossil fuels have all enhanced the interest in sustainable and renewable energy sources, including wave energy. Many concepts for wave power conversion have been invented. In order to extract a considerable amount of wave power, single Wave Energy Converters (abbreviated as WECs) will have to be arranged in arrays or ‘farms’ using a particular geometrical layout, comprising large numbers of devices. As a result of the interaction between the WECs within a farm, the overall power absorption is affected. In general, the incident waves are partly reflected, transmitted and absorbed by a single WEC. Also, the wave height behind a large farm of WECs is reduced and this reduction may influence neighbouring farms, other users in the sea or even the coastline (wake effects of a WEC farm). The numerical wave propagation model MILDwave has been recently used to study wake effects and energy absorption of farms of WECs, though without taking into account wave regeneration by wind in the lee of the WEC-farm which can be significant in large distances downwave the WECs. In this paper, the implementation of wave growth due to wind in the hyperbolic mild-slope equations of the wave propagation model, MILDwave is described. Several formulations for the energy input from wind found in literature are considered and implemented. The performance of these formulations in MILDwave is investigated and validated. The modified model MILDwave is then applied for the investigation of the influence of the wind on the wakes in the lee of a farm of wave energy converters.Copyright © 2011 by ASME