Showing papers on "Wave power published in 1995"

Cushioned dual-action constant speed wave power generator

Abstract: A wave power generator is substantially continuously driven by a pair of floats (22, 32) connected to a common drive shaft (12) and positioned side by side along a line perpendicular to the direction of wave motion (40), one float being specifically designed to efficiently drive the shaft during the rising portion of a wave, the other to efficiently drive the shaft during the falling portion of a wave. A flywheel (52) is maintained at a constant speed by an automatic load control throughout a range of wave patterns sufficient to encompass over 70% of the statistically expected wave patterns at the generator (54) location. An inclined-bottom float (22) is used for the rising wave drive, and a bottom-weighted float (32) is used for the falling wave drive. The floats (94, 96) may be disposed one above the other and may have mating conical surfaces (90, 92) for cushioning occasional contact between the floats.

Energy Flux from Traveling Hurricanes to the Oceanic Internal Wave Field

Abstract: The generation of long interval waves by traveling hurricanes on an f plane is studied within the context of linear theory. The emphasis of the present work is on the interval wave power, that is, the fraction of the energy input from the hurricane that is absorbed by the internal wave field in the ocean. Particular attention is paid to the dependence of the interval wave power on the hurricane speed, the oceanic stratification, and the Coriolis parameter. A formula for the wave power, expressed in terms of the wind-forcing spectrum, is derived. The wave power can be divided in two parts: one part generated by the divergence of the wind stress and one part generated by the curl of the wind stress. The latter part, which is dominating for hurricanes, is always decreased when the strength of the stratification is increased, while the former part may either increase or decrease depending on the speed of the hurricane. It is shown that, for a specified stratification and a fixed latitude, the wave po...

The sampling variability and the validation of high frequency radar measurements of the sea surface

Abstract: Remote sensing is becoming an increasingly important tool for ocean wave measurement, and over the past decade much progress has been made in the development of the wave measuring capabilities of HF (High Frequency) radar. This system is able to make detailed and near continuous observations of the sea surface over a wide area. However, because the mathematics of the data extraction process is rather difficult, the statistical properties of the observed data have to date been poorly understood. In this study, the approximate sampling distributions of a variety of measurements from HF radar (including significant waveheight, mean wave period, wind direction, and various spectral parameters) are derived in terms of quantities that are either known or estimable. The resulting confidence intervals are, in the case of significant waveheight and mean wave period, of comparable width to those obtained from the corresponding NURWEC2 (Netherlands UK Radar Wave buoy Experimental Comparison) wave buoy measurements, and in the case of spectral power, they are narrower. Furthermore, methods are derived by which such radar measurements may be compared with their corresponding wave buoy measurements in a statistically valid manner, and their relative biases estimated. These methods are then applied to data taken during the NURWEC2 field trial, which suggest that the radars and the wave buoy show good correspondence for measurements of significant waveheight and of spectral power (over 85 - 125mHz - the frequencies with most wave power, and hence those of most importance). There is also a fair correspondence for mean period measurements in the range 6.8 - 11.0secs. Spectral mean direction shows good correspondence over 85 - 155mHz over the somewhat limited directional range (i. e. as observed during the NURWEC2 storm) of the data.

The hydrodynamic performance of an oscillating water column wave energy converter

Abstract: A full description of the application of image shifting to the technique of particle image velocimetry (PIV) is given along with a discussion of the design and construction of a versatile rotating mirror image shifting system. The use of such a shifting system leads to systematic errors in the measured fluid velocities and it is shown that these errors can be accounted for and that a correction may be applied to eliminate them. A description of PIV itself and, in particular, the application of PIV to a study of the internal kinematics of an OWC in a wave flume is also provided. A simple semi-empirical model of the response of an OWC to a given wave climate is developed and its predictions are compared with air pressure and water level measurements obtained during flume tests of a model OWC. Finally detailed PIV time-series measurements, incorporating image shifting, are made of the flow within the OWC chamber and it is shown that as much as 7% of the wave energy may be lost due to viscous dissipation within the strong vortices which are formed around the submerged lip of the front wall of the model. Declaration This Thesis has been composed by me and, except where stated, the work contained is my own.

Model Studies of Oscillating Water Column Wave-Energy Device

Abstract: A harbor oscillating water column wave-energy device has been selected for the Indian pilot wave-energy program. The site has a water depth of about 12 m and an average annual wave-power potential of 13 kW/m. Such sites are attractive locations for fishing breakwaters. Due to the relatively low power potential, these oscillating water column devices are intended to be modules of a multifunctional breakwater. The present paper highlights the results of the scale-model experiments carried out on a prototype wave-energy caisson.

Combined wind-power and wave-power plant for electrical power generation

Abstract: The kinetic energy of the wind and the sea waves is utilised in the complete width and height of the plant, and is converted across a flywheel-generator combination in to electric power. The sails are arranged ring shaped. The sails are positioned analogous to a sailing ship travelling in a circle respectively according to the direction of the wind. The sail rotor (2) is seated on its outer rim and is displaced in a rotational movement. The wave paddles (20) are arranged diagonal to the wave front, to make possible a continuous transmission of the different incoming wave forces.

Field measurements of breaking wave loads on a shoreline wave power station

Abstract: Field measurements of breaking wave loads on a shoreline wave power station G.Muller, PhD, MSc, and T. T.Whittaker, PhD, MRINA J. W A wave load monitoring system for the Islay prototype wave power station was designed and installed. The monitoring system comprises a transducer module which houses five transducers and a selective data acquisition system. The system has been operational since January 1991. Six major storms with a duration of 24 days were monitored. So far, 2326 data records were taken and a maximum pressure of 51.3 kN/m-2, corresponding to 12% of the design pressure, was measured...

Surface wave driven generator

Abstract: The development of surface water wave power, as a source of energy, has made little progress in the last fifty years, due mainly to the high cost of converting intermittent energy into a more sustainable form. Two serious "prior art" projects, the British and the Japanese are examined in the "Disclosure". A model of a SURFACE WAVE DRIVEN GENERATOR is proposed which uses economical small scale and presently developed technology. Its distinguishable features from other inventions may be summarized as follows: - the concept of this machine implicitly challenges the notion that large industrial hydroelectric type of installations offer the ideal model for a successful development of wave energy. Instead, this is better achieved by smaller installations, which are capable of meeting the household needs of poor populations living off the coastlines of third world countries blessed with abundant, albeit unutilized wave energy. - this invention makes full use of two devices ¢flywheel, compressed air! capable of storing energy in order to correct the intermittent nature of wave power. In this respect, the most efficient energy storage device, the flywheel, plays the predominant role. - the performance and efficiency of the compressed air process are increased through a scientifically controlled solar exposure of the walls of the compressed air container. - operational costs are substantially reduced if the sensitive and vulnerable parts of the wave driven machine are stationed ashore where they are easily accessible for repairs and surveillance.

Floating body type wave power device

Abstract: PURPOSE:To realize a device simple in constitution and large in scale by converting energy in use of a coil-formed floating body so as to convert energy of wave to rotational energy in taking out as power. CONSTITUTION:A floating body 2 in coil form, having its central axis along the sea surface 1 is disposed, and pitch of the floating body 2 is set approximately to agree with average wavelength of wave. A position retaining means like a sea anchor 3 is disposed via a rotary joint 4b at tip of the floating member 2, to orient the coil-formed, floating member 2 in wave advancing direction. A rotation type power take-out mechanism like a generator 5 is disposed at the base end of the floating body 2. The floating member 2 is formed in coil having pitch nearly equal to wavelength of wave, so that rotational force is caused to the floating body 2 along with advance of wave.

Generator using free-wheel

Abstract: PURPOSE:To solve various problems by centralizing natural energy and thermal energy such as hydraulic power, wind force, wave power. geothermal energy, solar energy, biomass energy, ocean differential temperature energy and the power of an electric motor or the like to the rotation axis of the same generator by using the principle of a free-wheel and carrying out a generating operation combined with other uses. CONSTITUTION:The principle of a free-wheel 1 is used to transmit a plurality of power for generating electric power to the same rotation axis 8 of a generator 2. Thus, various kinds of energy sources are efficiently combined together and centralized to the rotation axis of the generator.

Experimentally determined profiles of fast wave current drive on DIII-D

Abstract: Profiles of non-inductive current driven by fast waves have been determined for reversed-shear DIII-D discharges. Both the current profile and toroidal electric field profile are determined from time sequences of equilibrium reconstructions. Using this information, the measured current profile has been separated into inductive and non-inductive portions. By comparing similar fast wave power, the portion of the total non-inductive current driven by fast waves were determined. The experimentally determined profiles of FWCD are in general agreement with theoretical predictions. Specifically, 135 kA was driven by 1.4 MW of rf power with a profile peaked inside {rho} = 2.

Ocean structure having wave power utilizing function

Abstract: PURPOSE:To suppress the fluctuation in a wavy condition by providing wings with a necessary form and size at the left side and the right side of an ocean structure main body, at the underwater position, in a structure provided with an air chamber at the front end of the ocean structure main body, and a wave energy converting device at the upper side of the air chamber CONSTITUTION:An air chamber 3 is provided at the front end of an ocean structure main body 1 having a buoyancy chambers 2 and 12, and openings 4 are formed at the lower front end of the air chamber 3, air holes 5 are provided at the ceiling of the air chamber 3, and power chambers 6 are provided at the outer side By utilizing the power of the air in the air chamber 3 which is boosted when the waves surge, air turbines provided in the power chambers 6 are rotated, so as to drive an energy converting device 7 In order to suppress the up and down movement by the waves 9 to reduce the variation of the water level in the air chamber 3, plate form of wings 15 are provided in the horizontal direction in the underwater position at the sides of the ocean structure main body 1 Consequently, the movement in the wavy condition of the ocean structure is reduced, and the absorbing efficiency of the wave energy is improved

RF-power upgrade system with resonant loading

Abstract: The RF-power upgrade systems with RF-field energy compression are intended for accelerating wave power increase in order to increase an accelerated beam energy or decrease the feeding RF-generators power. At present a number of energy compression system (ECS) types and designs with various properties are known. Among these a system with a resonant load presents the certain interest for practical use. The main difference of such ECS from the other types is that here a resonant load is an essential part of the system that influence significantly the parameters. They are systems with connected resonators.

Analysis of wave power plants as oscillatory systems

Abstract: The analysis of oscillatory phenomena, which was performed in this paper, enables developers of wave power plants to analyze rather simply the operating conditions and calculate the basic parameters of the elements of the oscillatory systems with allowance for the given energy spectrum of the waves.