NO850512L - ARRIVALS FOR CHARGING POWER PLANTS. - Google Patents

Description

Wave power on the dive, rotating body

1. Hiring.

A submerged body is exposed to wave forces.

We have discovered that if the body is given a rotation around an axis that passes through the body, the wave forces on

the body changes significantly. Depending on the direction of incidence of the waves in relation to the axis of rotation, the direction of rotation and the speed of rotation, the forces on the body can be both substantially greater and substantially less than the wave forces without rotation. With the help of the rotation, the wave forces on a body can therefore

largely controlled. F*- y^- f ,;The body is preferably rotationally symmetrical with regard to rotation about the axis of rotation, e.g. a cylinder that rotates about the cylinder axis. We have experimentally demonstrated that if the cylinder was given a constant rotation about the cylinder axis, the forces increased by a factor of up to 6 compared to the forces on a non-rotating cylinder. We could also reduce the forces on the cylinder by reversing the direction of rotation.' ;2. Applications in wave power plants. Submerged bodies exposed to wave forces can be used to convert wave energy into useful energy. The wave forces set the body in motion. By damping the swing arm with a damping mechanism, useful energy can be produced. For example, the body can be co-loaded to the bottom via pumps. When the body is set in motion, the liquid will be pumped through a hydraulic motor or turbine, which in turn drives an electric generator. The so-called Bristol cylinder (British proposal for a wave power plant) works according to such a principle. If the forces on the submerged body increase, the energy production will also increase. This can therefore be achieved by rotating the body. Depending on the direction of rotation, the forces on the body can also be reduced. This may be of interest to reduce the stresses on the wave power plant in extreme wave heights. It may also be of interest to regulate energy production, e.g. in relation to consumption. This can then be done by regulating the direction of rotation and the rotational speed of the body. An important requirement for bow power plants is that the damping mechanism works between the body and a point that is fixed or at least has a relative movement in relation to the body. Such a fixed point can e.g. be the seabed. This applies to the "Bristol cylinder". But the bottom may be far down. In addition, it is usually expensive to obtain an anchoring point on the bottom which must bear relatively large forces. Rotating play chambers can eliminate the need to go to the bottom to obtain the necessary reference point. Let us imagine two parallel cylinders rotating in opposite directions. These are exposed to rotation-induced wave forces. But because the cylinders rotate in the opposite direction, these wave forces are also in the opposite direction. The cylinders will therefore oscillate with opposite phase and the distance between them will thus vary in time with the waves. If we now connect pumps between the cylinders, they will be able to produce energy. We therefore see that we now have the necessary reference within the system itself. The need for an external reference point against which the pumps can work, e.g. the bottom, is thus eliminated. With this method, one can reach e.g. make floating power plants with conventional anchoring systems to hold the power plant in place. ;Circulation without rotation of the body;The rotation of the cylinder sets up a circulation of water around the cylinder. The combination of the circulating water and the oscillating water in the wave is what gives rise to the rotation-induced wave forces. If it is then possible to create circulation of water in an alternative way to letting the cylinder itself rotate, this will have the same effect as far as the wave forces on the cylinder are concerned. One way to do this is e.g. to make slot-shaped, slanted openings in the cylinder wall through which water is pumped out in such a way that a circulation is set up around the cylinder. By regulating the speed of the water out through the slits, the wave forces on the cylinder can be regulated. 5yes Another way to create circulation is to put a propeller on the outside of the body and in that way establish a circulation one way or the other around the body. Sjc<h>' <■■ Y^~*~

The rotation axis or circulation axis of the body can have different orientations in relation to the direction of incidence of the wave and to the angular direction.

The body does not need to be completely submerged either, but can

be half submerged. A completely submerged body can nevertheless have certain advantages because the wave forces will then increase approximately linearly with the wave amplitude.

If the body has the shape of a plate or a wing-

profile, a translation of the vane in the water in the same plane as the plane of the vane or alternatively a forced water-

flow past the vane, give an extra lifting force on the vane in waves. ^ jc1 -£x'y^u

Vane profiles

An airplane wing provides lift because the wing sets up a circulation of air around the wing due to the vane's design and the angle of the vane in relation to the air flow past the vane.

Correspondingly, wave-induced lifting forces can be achieved

on the dive, wing-shaped playrooms. The operation is analogous to that which applies to a rotating cylinder, except

that the lifting forces do not increase linearly with the wave height,

as is approximately the case for rotating cylinders. «->J a q

3. Applications in offshore constructions.

The wave forces on "offshore" constructions induce

unwanted movements on the structures. By controlling the forces on e.g. pontoons to semi-submersible platforms, the total wave force on the structure as a whole can be minimised. If the forces are small, so is that

the movements small. Rotating spawning chambers^forced water currents around or past spawning chambers and/or wing design of spawning chambers can thus be used to reduce the movements of "offshore constructions".

Claims (7)

1. Device for influencing the wave forces on a submerged body, characterized in that a liquid circulation has been established around the body. 2. Device in accordance with claim 1, characterized in that the circulation is established by the body rotating around an axis through the body. 3. Device in accordance with claim 1, characterized in that nozzles are placed on the surface of the body and that liquid is pumped through the nozzles tangentially to the surface of the body, so that a liquid circulation is created around the body. 4. Device in accordance with claim 1, characterized in that two or more propellers are placed at different locations around the periphery of the body and where the propellers are arranged to generate a liquid stream in the same direction around the body, so that in an efficient way, a circulation is established around the body. 5. Device in accordance with claim 1, characterized in that the body is designed with a wing profile. 6. Device in accordance with requirements 2 to 5 and where the device is designed for the absorption of wave energy^characterized by the fact that body chambers with parallel circulation axes are used, but with opposite circulation directions, so that the oscillating wave forces are oppositely directed at the bodies and that pumps or the like are placed between the bodies for the conversion of wave energy into useful energy by the fact that the relative distance between the bodies oscillates in time with the wave forces. 7. Device for stabilizing floating structures in waves, characterized by establishing circulation around a submerged part of the structure in accordance with requirements 2 to 5.