JP4958403B2 - Wave power generation method - Google Patents

Description

The present invention relates to a wave power generation method for generating electric power by extracting electric energy from wave power.

  In wave power generation, wave energy in the ocean is used as power to rotate a turbine and operate a generator, which is converted into electric energy for use. In order to use this wave energy, it is converted into mechanical energy such as air energy and mechanical energy. The converted mechanical energy is further taken out as electrical energy using a turbine, a generator or the like.

  In other words, this wave power generation is divided into two methods: a method for converting wave power into air energy and rotating the turbine based on this, and a method for converting wave power into mechanical energy and rotating the turbine based on this. It will be divided roughly.

  Conventionally, a wave power generation device 106 as shown in FIG. 14 has been proposed as a method for converting wave power into air energy. The wave power generation device 106 is constructed by building a breakwater 102 on a wide area mound 101 provided on the seabed of a harbor or the like, incorporating caissons in the breakwater 102 in the vertical direction, and forming an opening 103a that leads to open sea water. And an air damper chamber 104 and a power generation chamber 105 disposed above the air chamber 103.

  The wave power generation device 106 includes a vent hole 107 that allows the air chamber 103 and the air damper chamber 104 to communicate with each other, an input port 108 that allows the air damper chamber 104 and the power generation chamber 105 to communicate with each other, and the power generation chamber 105 and the outside. A communicating intake / exhaust port 109 is formed in the partition wall of each chamber.

  Further, a dust removing screen 110 is formed in the vent hole 107, an input pipe 111 is attached to the input port 108 toward the inside of the air damper chamber 104, and a float valve 112 is disposed at the tip thereof. ing. A turbine 113 and a generator 114 are disposed at the input port 108 of the power generation chamber 105. The wave power generation device 106 having such a configuration obtains electric energy by operating the turbine 113 and the generator 114 by causing the ocean waves to move up and down the water surface of the air chamber 103 and swinging the air inside. .

  In particular, in recent years, it is possible to prevent the intrusion of seawater into the power generation chamber 105 by using the properties of the fluid without increasing the height of a building such as an air chamber without using a special complicated mechanism. A wave power generator has also been proposed (see, for example, Patent Document 1).

  In the wave power generation device 130 disclosed in Patent Document 1, for example, as shown in FIG. 15, a seawater reduction chamber 152 is provided between an air chamber 133 and a power generation chamber 135 that houses a turbine 143 and a generator 144. The air chamber 133 and the seawater reduction chamber 152 are communicated with each other through a ventilation pipe 153, and the seawater reduction chamber 152 and the turbine 143 of the power generation chamber 135 are communicated with each other through an input pipe 154.

  In this wave power generation device 130, the wave pressure in the air chamber 133 raises and lowers the air above, and the electric energy is acquired by operating the turbine 143 connected through the vent pipe 153 and the seawater reducing chamber 152. However, when the sea level rises when an abnormal wave height is applied, the air that escapes upward from the air chamber 133 is throttled sufficiently small by the vent pipe 153 and expanded by the seawater reducing chamber 152. As a result, in the seawater reduction chamber 152, the rising speed of the sea surface is slowed, so that it is possible to prevent the influence of abnormal seawater rising without providing a special mechanism.

  As a method for converting wave power into mechanical energy, a so-called pendulum type wave power generation device that applies force from a wave force to a generator through a pendulum has been proposed. This pendulum type is a wave power generation system that captures wave energy as a pendulum motion of a pressure receiving plate and converts it into hydraulic pressure.

  Normally, when a wave traveling from offshore hits a wall, a retreating wave is generated, and both waves mix to form a wave called a standing wave in front of the wall. This standing wave consists of a “belly” of vibrations in which water particles move up and down and a “node” part that moves horizontally. If a movable object is placed on this node part, the energy can be absorbed. The pendulum type applies a pendulum as such a movable object.

Further, with regard to wave power generation turbines, research has progressed especially in recent years. For example, as disclosed in Patent Document 2, for wave power capable of maximizing the energy brought by waves. A valveless turbine with a guide plate air outlet has also been proposed. In the turbine disclosed in Patent Document 2, a notch serving as an air outlet and suction port is opened above and below the turbine exterior, surrounded by an air outlet serving also as a guide plate, and a runner is placed therein.
JP-A-10-246171 JP 2000-87838 A

  By the way, in the conventional wave power generator described above, it is necessary to once convert wave energy into mechanical energy such as air energy or mechanical energy. In comparison, only a small amount of energy can be obtained. That is, it is difficult to improve energy efficiency as compared with the case where wave energy is directly converted into electrical energy. For this reason, the initial cost has become much higher, which has become a major barrier to the realization of wave power generation itself.

Accordingly, the present invention has been devised in view of the above-described problems, and an object thereof is to provide a wave power generation method capable of further improving energy efficiency.

In addition, the wave power generation method to which the present invention is applied includes a first wall and a second wall that are erected at intervals from each other, and approximately from the lower end of the first wall to the lower end of the second wall. The water is surrounded by a horizontal plate disposed in the horizontal direction, and a vortex of water is generated in the water reserving chamber in which an opening is formed in the lower portion of the first wall, and according to the vortex, The rotating shaft to which the blades under the water surface are fixed is rotated, and electric energy based on the rotation of the rotating shaft is extracted to generate electric power.

  A water turbine having a rotating shaft to which arc blades are fixed rotates counterclockwise based on this steady vortex. As a result, wave energy can be directly converted into electrical energy, and energy efficiency can be further improved as compared to the case where it is once converted into mechanical energy such as air energy or mechanical energy. Become. For this reason, it becomes possible to suppress initial cost, and it becomes possible to greatly improve the feasibility of wave power generation itself.

Hereinafter, as a best mode for carrying out the present invention, a wave power generation method for generating electric power by extracting electric energy from wave power will be described in detail with reference to the drawings.

  FIG. 1 shows a wave power generator 1 to which the present invention is applied. This wave power generator 1 is a lower transmission type and has a double curtain type structure, and is adjusted so that the drowning of the drooping wall 2 on the sea side is shallower than the impermeable wall 3 on the land side. Yes. That is, it is provided so that the flooded lower end 2 a located at the lower end of the drooping wall 2 is closer to the hydrostatic surface 4 than the flooded lower end 3 a located at the lower end of the impermeable wall 3. The hanging wall 2 and the impervious wall 3 are arranged in parallel with a space between each other, and a water-reserving chamber 10 is formed between the walls 2 and 3. Incidentally, it is assumed that the hydrostatic surface 4 in the water reserving chamber 10 is open to the outside.

  In the wave power generation device 1 configured with such different double water curtain walls, a lower water passage opening 6 a is formed between the lower water bottom 3 a of the impermeable wall 3 and the sea floor 5. Yes.

  Further, a submerged horizontal plate 8 is disposed in a horizontal direction at a height substantially coinciding with the upper end of the lower water passage opening 6a and from the flooded lower end 2a to the flooded lower end 3a. The submerged horizontal plate 8 enables control of vortex water generated from the lower end of the drooping wall 2 due to transmission wave reduction and wave action, and generation of an off-shore unidirectional flow by the control effect. An opening 7 is formed from the lower end of the hanging wall 2 to the submerged horizontal plate 8. Seawater goes back and forth from the opening 7 into the water reserving chamber 10.

  Further, the wave power generation device 1 is provided with a power generation unit 11 that generates power by using a vortex of seawater generated in a specific direction in the water reserving chamber 10 as power.

  The power generation unit 11 generates electric power by taking out electric energy by rotating the rotation shaft 13 that plays a role as a so-called water wheel having a circular arc blade 12 fixed thereto and rotating the rotation shaft 13 based on the vortex of seawater. It has a generator that does not. Incidentally, the circular arc blade 12 may be configured by a blade having any shape.

  2A is a view of the power generation unit 11 as viewed from the direction A in FIG. 1, and FIG. 2B is a cross-sectional view of the power generation unit 11. The arc blade 12 is made of, for example, a material such as vinyl chloride, and is fixed around the rotation shaft 13 at an interval of about 180 °. Incidentally, the arc blades 12 are not limited to such a configuration, and may be configured in any shape and any number of angles at any angular interval. The rotating shaft 13 is supported by a bearing 15. As this bearing 15, for example, a ball bearing bearing using a sphere as a rotating body is applied, and friction caused by the rotation of the rotating shaft 13 can be effectively reduced. As a result, the rotating shaft 13 can be smoothly rotated by receiving the wave force, and the position thereof is strongly held.

  Discs 16 are respectively disposed at both ends of the rotating shaft 13. By disposing the disk 16, seawater can be effectively taken in and the arc blade 12 can be propelled, and as a result, the rotational driving force of the rotating shaft 13 can be increased. Incidentally, the configuration of the disk 16 may be omitted. The rotating shaft 13 may be adjusted so as to be substantially the same height as the lower end of the hanging wall 2 in the vertical direction.

  The generator 14 is a so-called prime mover that receives pressure based on the vortex of seawater, converts wave energy into energy of rotational motion based on the rotating shaft 13, and extracts kinetic energy therefrom.

  In the example shown in FIG. 2, the case where two water turbines including the arc blade 12 and the rotating shaft 13 are provided has been described as an example. However, the present invention is not limited to such a configuration. Any number may be used.

  In the wave power generation device 1 having such a configuration, a water flow function such as a tidal current and a wave current is maintained by the seawater permeation section 6 formed between the submerged horizontal plate 8 and the seabed, and the water chamber is also provided. A vortex flow is generated from the flooded lower end portion 3a using the piston mode wave motion in 10 and the energy of the wave motion is finally efficiently converted into one-way flow energy.

  At this time, as shown in FIG. 3, the submerged horizontal plate 8 accumulates counterclockwise vortex flow in the state shown in the drawing in the water chamber 10, and this vortex flow interferes with the fluid flowing in the seawater permeable portion 6. It is possible to suppress the effect. In other words, the submerged horizontal plate 8 forms a lower water passage extending in the front-rear direction in the seawater permeation portion 6, and particularly plays a role of forming a ceiling surface in the seawater permeation portion 6.

  As shown in FIG. 3, the fluid flowing through the seawater permeable portion 6 is forced to be rectified into a water flow in a predetermined direction by the seawater permeable portion 6 formed of the submerged horizontal plate 8 and the sea of the drooping wall 2. Because it is strongly influenced by the clockwise vortex formed on the side, it is transported to the sea side when averaged over one wave period. That is, the submerged horizontal plate 8 that forms the seawater permeable portion 6 plays a role of causing an average flow of seawater from the land side toward the sea side, thereby further promoting the exchange of seawater inside and outside the harbor. It will be.

  Further, by providing such a seawater permeable portion 6, a counterclockwise vortex generated from the lower end of the drooping wall 2 along with the wave motion is accumulated in the water reserving chamber 10. This vortex flows constantly in a specific direction of rotation regardless of the time phase. The strength of this steady eddy current is also related to the magnitude of the average transport flow rate in the offshore direction through the seawater permeation section 6.

  For this reason, the water wheel consisting of the rotating shaft 13 to which the circular arc blade 12 is fixed rotates counterclockwise based on this steady vortex. As a result, wave energy can be directly converted into electrical energy, and energy efficiency can be further improved as compared to the case where it is once converted into mechanical energy such as air energy or mechanical energy. Become. For this reason, it becomes possible to suppress initial cost, and it becomes possible to greatly improve the feasibility of wave power generation itself.

  In addition, this invention is not limited to embodiment mentioned above, For example, as shown in FIG. 4, the chamfering part 9 by which the chamfering was made about the at least one corner part of the water-reservoir chamber 10 may be formed. . As a result, the steady vortex described above can be generated more efficiently, and the energy efficiency can be further improved.

  Hereinafter, the result of examining the possibility of utilizing the power generation by taking in the rotational kinetic energy of the vortex flow in the water reserving chamber 10 by the arc blade 12 will be described.

  The model used for this examination experiment has the same cross section as the wave power generator 1 as shown in FIG. 1, and the length of one dam body is 50 cm. In the experiment, two models 21 of the wave power generation device 1 were manufactured so as to occupy the entire water channel width of 1 m. By the way, the scale of the manufactured model 21 is 1/20.

  Next, the model 21 of the produced wave power generation device 1 is provided in a wave-making water tank. As shown in FIG. 5, the wave water tank 20 is a long water channel having a length of 100 m, a width of 2 m, and a height of 2 m. The wave-making water tank 20 is divided into two substantially in the width direction by a partition wall 28 made of concrete, and two models 21 of the wave power generator 1 are fixed in a test water channel 20a having a width of 1 m on one side. The other water channel 20b in the wave-making water tank 20 is provided with a permeable wave breaker 22 at the end. As a result, it is possible to prevent the water from easily flowing back and causing a difference in water level when an average flow occurs in the test water channel 20a.

  In the test channel 20a, a slope 25 having a 1/30 gradient is formed, and a horizontal floor 26 is laid so as to be smoothly connected to the top 25a. The model 21 was fixed on the horizontal floor 26 with bolts and nuts (not shown). By the way, the installation position of the rotating shaft 13 in the model 21 is selected after a plurality of trials and errors at a position considered to have the highest number of rotations for a specific wave condition.

  In the experiment, the wave height of the incident wave was measured with a capacitive wave height meter (not shown) provided near the start end of the 1/30 slope in the test channel. Regarding the reflected wave from the model 21, two capacitive wave height meters were installed on the sea side of the model 21, and the wave height was measured by reading the water surface fluctuation record. Furthermore, the reflectance was obtained from the water surface fluctuation records of these two wave height meters through the separation and estimation method of the incoming reflected wave.

  Further, by installing one capacitive wave height meter on the land side of the model 21 and in the water chamber 10 of the model 21, the transmitted wave height and the wave height in the water chamber 10 can be measured. I was able to do it.

  Moreover, in order to be able to measure the horizontal flow velocity in the seawater permeation | transmission part 6, the electromagnetic anemometer was installed in the lower water flow opening 6a periphery.

The wave conditions used were as shown in the following table.

  FIG. 6 shows the number of rotations N of the circular arc blade 12 per wave period as a change due to the wave period T. From FIG. 6, it can be seen that the rotation speed N per wave cycle of the arc blade 12 increases when the wave cycle is long and the action wave height H is large, and is approximately 2.5 rotations.

  The reason why the rotational speed N increases when the acting wave height H is large is considered to be that the amount of vortex from the lower end of the hanging wall 2 increases excessively. Moreover, it is considered that the reason why the rotational speed increases as the period of the action wave becomes longer is that the amplification degree of the piston mode wave motion in the water reserving chamber 10 becomes larger on the long period side. This is a diagram showing the relationship between the rotational speed of the arc blade 12 and the ratio of the wavelength L and the water chamber width B (= L / B), and the relationship between the reflectance Cr and the transmittance Ct with respect to the L / B. It can be inferred to some extent from the comparison with 8.

  FIG. 9 shows the average rotational angular velocity of the arc blade 12. In any periodic condition, the average rotational angular velocity tends to increase when the acting wave height is large. The rotational angular velocity was about 8-9 radian / s when the wave height H was about 10 cm with little change due to the wave period. In this experiment, only two types of working wave heights of 5 cm and 10 cm are employed, but it is presumed that the rotational angular velocity further increases under higher wave height conditions.

  FIG. 10 shows a temporal change in the rotational speed of the arc blade 12 when the wave period T is 1.4 s as a representative example. From FIG. 10, it can be seen that the rotational angular velocity has a temporal fluctuation component, but the steady velocity component has an outstanding magnitude, suggesting that it can be used as a power source for wave power generation. Yes.

  FIG. 11 shows the results of the reflectance Cr and the transmittance Ct when a water turbine is installed in the water reserving chamber, as a change in the wavelength / water reserving chamber width ratio L / B. In FIG. 11, the calculation result by the attenuation wave theory is also shown. However, in this calculation result, it is assumed that there is no influence from the turbine.

  From the comparison between FIG. 11 and FIG. 8 where there is no water wheel, the effect of installing the water wheel is that the L / B condition in which the minimum value of the reflectance appears shifts to the larger long period side. I understand. However, with respect to the transmittance, there was almost no effect due to the installation of the water turbine.

  FIG. 12 shows the change of the wave height in the water reserving chamber 10 due to L / B. In FIG. 12, the wave height Hc in the water reserving chamber 10 is represented by the wave height amplification degree obtained by dividing the wave height Hc by the incident wave height H.

  From this figure, the reflectance is reduced in the vicinity of L / B = 12, where the wave height amplification is relatively large, and the rotation speed of the water turbine increases to 2.5 rotations / cycle after this condition. It can be confirmed that Thus, it is considered that the reason why the reflected wave divergence and the rotation speed of the water turbine become remarkable is due to the amplification of the piston mode wave motion in the water-reservoir chamber.

  As described above, for the purpose of acquiring wave energy, experimental studies have been conducted on the effectiveness of the method using the kinetic energy of the vortex flow formed in the water reserving chamber 10.

  As a result, the water wheel provided in the water reserving chamber 10 is rotated in one direction at a rate of about 1.5 to 2.5 rotations per wave cycle by the one-way rotating vortex generated in the water reserving chamber 10. There was found. It was also confirmed that the number of rotations showed an increasing tendency as the incident wave height and wave period increased.

  And when this wave power generation device 1 is used as a breakwater, there is almost no effect on the reduction of transmitted waves and reflected waves, which is a function of the breakwater, due to the provision of a water turbine in the aquatic chamber 10. I understood. However, it has been confirmed that the wave period at which the reflectance is minimized shifts to the long period side to some extent by providing a water wheel.

  In the above-described embodiment, the case where the hanging wall 2 and the impermeable wall are arranged from the sea side to the land side is described as an example. However, the present invention is not limited to this configuration, and the sea, river, lake, etc. It may be arranged in any direction at any location where the water flow exists.

  The wave power generator 1 to which the present invention is applied may be configured so that the land-side impermeable wall 3 is in contact with the shore 31 as shown in FIG. In the configuration of FIG. 13, the same elements and members as those of the configuration of FIG. 1 described above are denoted by the same reference numerals and description thereof is omitted here. In the configuration of FIG. 13, as a result of fixing the lower end of the impermeable wall 3 to the seabed 5, the impermeable wall 3 is also extended to a portion corresponding to the lower water passage opening 6 a. Further, the seawater does not pass through the seawater transmission part 6.

  In such a case as well, seawater goes back and forth from the opening 7 into the water reserving chamber 10. As a result, it is possible to generate a steady vortex in the water reserving chamber 10, and the water turbine formed of the rotating shaft 13 to which the circular arc blade 12 is fixed can be rotated counterclockwise to generate electric power.

  Further, as shown in FIG. 13, the present invention may include the case where the land-side impermeable wall 3 is disposed on the sea without contacting the shore 31.

Furthermore, the wave power generator 1 to which the present invention is applied is not limited to the case where the drooping wall 2 provided on the sea side and the impermeable wall 3 provided on the land side are provided, and these are spaced apart from each other. Alternatively, the first wall and the second wall may be replaced with each other. The first wall and the second wall are not limited to the case where the first wall and the second wall are provided on the sea side and the land side, respectively, and may be disposed at any location in the water. The submerged horizontal plate 8 may be replaced with any horizontal plate.

It is a figure showing a wave power generator to which the present invention is applied. It is a cross-sectional view of a power generation unit. It is a figure for demonstrating about the steady vortex | eddy_current produced | generated in a reclaimed water chamber. It is a figure which shows the example which formed the chamfering part in the corner in a water-reservoir chamber. It is a figure shown about the experimental system of the wave power generator to which this invention is applied. It is a figure which shows the data of the rotation speed of the water wheel per wave cycle. It is a figure which shows the data which made wavelength / water storage room width ratio L / B the horizontal axis | shaft with respect to the rotation speed of the water wheel per cycle of a wave. It is a figure which shows the relationship between transmission and a reflectance. It is a figure which shows the data of the average rotational angular velocity of a circular arc blade | wing. It is a figure which shows the time change of the rotational speed of the circular arc blade | blade in case the wave period T is 1.4 s. It is the figure which showed the result of the reflectance and the transmittance | permeability when a water wheel was installed in the water play room with the change of wavelength and water play room width ratio L / B. It is a figure which shows the change by L / B of the wave height in a water play room. It is a figure which shows the other example in the wave power generator to which this invention is applied. It is a figure which shows the conventional wave power generator. It is another figure which shows the conventional wave power generator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Wave power generator 2 Drooping wall 3 Impervious wall 4 Still water surface 5 Sea bottom part 6 Seawater permeation part 7 Opening part 8 Submerged horizontal plate 9 Chamfering part 10 Reservoir chamber 11 Power generation part 12 Arc blade 13 Rotating shaft 14 Generator 15 Bearing 16 Disc

Claims (1)

A first wall and a second wall which are erected at intervals from each other, and a horizontal plate which is disposed in a substantially horizontal direction from the lower end of the first wall to the lower end of the second wall. A water eddy current is generated in the water reserving chamber which is surrounded and has an opening formed in the lower portion of the first wall;
A wave power generation method characterized in that, in accordance with the eddy current, a rotating shaft to which a blade under the water surface is fixed is rotated, and electric energy based on the rotation of the rotating shaft is extracted to generate electric power.

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