JP5278900B2 - Method and apparatus for converting water energy into electrical power - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for converting water energy to electric power and the apparatus thereof by using water flow in which it is considered that a flutter phenomenon does not generally occur in the prior art. <P>SOLUTION: The method comprises the steps of generating a flutter phenomenon to a blade (01) which is immersed into water flow, extracting reciprocally translational motion, which is a motion of crossing the flow, from the oscillation of the blade (01) constituting the flutter phenomenon to convert the motion into electric power, and converting the reciprocally translational motion into the reciprocally rotational motion of a disc (14) to provide rotational inertia moment to perform mass addition of a value which is necessary to generate the flutter phenomenon. For this, the blade (01) is elastically supported by leaf springs (05, 05) such that the blade can be moved in reciprocal translation, as well as, the reciprocally translational motion of the blade is converted into the reciprocally rotational motion of the disc (14) through a ball screw shaft (11). <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a method and apparatus for generating flutter phenomenon in an air flow and converting the water energy into electric power, although flutter phenomenon is generally considered to occur in an object in the air flow.

  Power generation by windmills aimed at energy conservation and global warming suppression is widespread in various parts of the world, and there are many places where it is part of the landscape, so it is extremely common and is expected to increase in the future. However, in Japan, there is a problem that there are few places and frequencies where a wind of 10 to 15 m / s, which is a general design wind speed, blows. In addition, since the amount of power generation is proportional to the cube of the wind speed, there is a problem that the amount of power generation drops sharply as the wind speed decreases.

In addition, attempts have been made to provide a hollow air collecting cylinder that contracts or expands along the direction of the wind in order to reduce the wind flow and increase the wind speed locally so that power can be generated even at low speed (for example, non- Patent document 1), the effect is not as great as expected, and if it is a small scale, it will be difficult to install the cylinder. Although the blades are lengthened in order to increase the power generation amount per unit, there is also a problem that the peripheral speed increases and the noise increases as the power is increased.
Yuji Oya, “Wind Power Generation Using the Wind Lens Effect”, A & A Seminar, May, 2001

  On the other hand, some attempts have been made to obtain power by effectively utilizing the flutter phenomenon, which is a destructive self-excited vibration that occurs in aircraft wings and suspension bridges, etc., compared to the radial wings of windmills. By arranging the blades in a row, there is an advantage that wind energy can be used effectively and power generation efficiency is increased (for example, Non-Patent Documents 2 to 4). As an example of the above destructive self-excited vibration, the collapse of the Tacoma Bridge that occurred in Washington in the United States in 1940 has been documented and is famous.

The movement of the wing due to this flutter phenomenon is
(1) Pitching motion (reciprocating rotational motion) in which the blades change the angle of attack with respect to the flow.
(2) Superposition of reciprocal translational movements where the wing moves across the flow. The movements of (1) and (2) are almost 90 degrees out of phase, and as a result, the wings are twisted by fish. Exercise like swimming. Power generation is performed using the movement (2) of the above movements.

Duncan, J.W., `` The Fundumentals of Flutter '', R & M No. 2417, Nov. 1948 Mckinney, W. and DeLaurier, J., `` The Wingmill: An Oscillating Wing Windmill '', Journal of Energy, Vol. 5, No. 2, March-April 1981 Koji Kaiga et al., “Conceptual design of flutter power generation using CFD”, Special Reference No.57, National Aerospace Laboratory

  On the other hand, the history of water turbines that use hydropower, that is, kinetic energy of water, is old, and hydropower generation that generates electricity by converting the energy of the water stored by the dam into kinetic energy is widely used all over the world. As is well known. In addition, dams have brought tremendous benefits to flood control, irrigation to agricultural land, drinking water, industrial water, etc., but it may be partly due to natural destruction by the dam construction, local disappearance, but local industries and residents Numerous adverse effects have been pointed out, such as obstruction of life, abnormal algae due to insufficient oxygen in stored water, and deterioration of water quality.

  On the other hand, in Japan, there are many small and medium-sized rivers with relatively high flow speeds, so there is a potential for small and medium-sized rivers that directly use the flow of water (kinetic energy), which does not depend on the dams and has almost no adverse effects described above. There are strong expectations for hydropower use, especially power generation. However, the flutter phenomenon due to the flow of water did not occur as a natural phenomenon, or because the negative image about the flutter phenomenon was strong, it has a specific gravity 800 times that of air and is about 1/10 of the wind speed. Although it is possible to generate electricity at a flow rate and it is advantageous compared to air, there has been no idea to use it effectively until now.

  In order to cause the flutter phenomenon due to the water, details are omitted, but the theoretical mass of the wing is about 10 times the imaginary mass of the fluid to which it is exposed (the mass of the cylinder whose diameter is the chord). The above is necessary. For example, while the mass of the wing in the above-mentioned example of shellfish wind power generation is 233 kg, if water is used, a mass of 180 t or more is necessary, and therefore hydroelectric power generation using water flow cannot be realized as it is. Is obvious and a mechanism is needed to increase the mass by some means.

As a mass addition mechanism for translational motion, a method is known in which translational motion is converted into rotational motion to rotate a rotating body such as a disk and the rotational inertia moment of the rotating body such as a disk is used. By applying this method, the inertial mass involved in the vertical vibration of the seismic isolation target structure is increased, and the vertical vibration of the seismic isolation target structure is lengthened to obtain a vertical seismic isolation effect. A seismic isolation device has been proposed (for example, Patent Document 1).
JP 2004-44748 A

  In view of the above, in order to eliminate the above-mentioned drawbacks of the prior art, the present invention adds the mass necessary for causing the flutter phenomenon to the blades even in the flow of water by the rotational moment of inertia of the rotating body including the disk. It is an object of the present invention to provide a method and an apparatus for converting water energy into electric power.

  The method of converting the energy of water of the first invention for solving the above-mentioned problem is to cause flutter phenomenon in a blade immersed in a flow of water, and among vibrations of the blade constituting the flutter phenomenon. Extracting the reciprocating translational motion that moves across the flow, converting it to electric power, and converting the reciprocating translational motion into the reciprocating rotational motion of the rotating body, adding the mass addition necessary to cause the flutter phenomenon And is performed by the rotational moment of inertia.

  In addition to the configuration of the first invention, the second invention is characterized in that the blade is elastically supported by a leaf spring so as to be capable of reciprocating translation.

The third invention is characterized in that, in addition to the configuration of the first or second invention, the reciprocating translational motion of the blade is converted into the reciprocating rotational motion of the rotating body via a ball screw.
Here, the ball screw is a combination of a ball screw shaft constituting a male screw portion and a female screw portion to which the ball screw shaft is screwed.

  According to a fourth aspect of the invention, in addition to any one of the first to third aspects of the invention, pitching motion (reciprocating rotational motion) that changes the angle of attack with respect to the flow of the blade vibration constituting the flutter phenomenon. ) Is forcibly raised by a motor.

  According to a fifth aspect of the invention, in addition to any one of the configurations of the first to fourth aspects, the cross-sectional shape of the blade is symmetrical in the front-rear direction, and the center of the pitching motion (reciprocating rotational motion) is the center of the chord. And

  A device for converting water energy into electric power according to a sixth aspect of the invention is a blade that immerses in a water flow and causes a flutter phenomenon, and the flutter: the vibration of the blade based on the phenomenon so as to cross the water flow. And a rotating body that reciprocally rotates in conjunction with the moving reciprocating translational movement, and the rotating body can ensure mass addition of a value necessary for causing the flutter phenomenon by the moment of inertia. It is characterized by being.

  According to a seventh aspect of the invention, in addition to the configuration of the sixth aspect of the invention, there is provided a pair of isometric parallel leaf springs that elastically support a reciprocating translation member that reciprocally translates in conjunction with the wing so that the wing can be reciprocally translated. It is characterized by having.

  The eighth invention is characterized in that, in addition to the configuration of the sixth or seventh invention, a ball screw for converting the reciprocating translational motion of the blade into the reciprocating rotational motion of the rotating body is provided.

  A ninth aspect of the invention includes, in addition to any one of the constitutions of the sixth to eighth aspects, pitching motion (reciprocating rotational motion) of the blade vibration constituting the flutter phenomenon in which the blade changes the angle of attack with respect to the flow. ) Is forcibly raised.

  In addition to any of the configurations of the sixth to ninth inventions, the tenth invention includes a wing whose cross-sectional shape is symmetric in the longitudinal direction and whose pitching motion (reciprocating motion) is the center of the chord. It is characterized by that.

  According to the first aspect of the present invention, mass can be added very easily by the rotating body, and flutter phenomenon can be caused to the wing immersed in the flow of water, which does not normally occur, thereby The received water energy can be easily converted into electric power.

  According to the second invention, in addition to the function and effect of the first invention, the frequency of the reciprocating translational motion of the blade converted into electric power can be set to a predetermined frequency by the leaf spring, and the reciprocation thereof. Translational motion can be guided almost without friction loss.

  According to the third aspect of the invention, in addition to the effects of the first or second aspect of the invention, the mass addition effect can be easily adjusted with almost no friction loss simply by changing the lead of the ball screw.

  According to the fourth invention, in addition to the operational effects of any of the first to third inventions, the flutter phenomenon of the blades can be stably caused by the slight electric power applied by the motor.

  According to the fifth aspect, in addition to the effects of any one of the first to fourth aspects, the flutter phenomenon of the blade can be stably caused even when the direction of the water flow is reversed.

  According to the sixth aspect of the present invention, it is possible to easily add a mass of a value necessary for causing a flutter phenomenon to occur on a wing immersed in a flow of water that does not normally occur by the rotating body. It becomes possible to easily convert the energy of water into electric power using the phenomenon.

  According to the seventh invention, in addition to the function and effect of the sixth invention, the leaf spring provides a restoring force for making the frequency of the reciprocating translational motion of the blade converted into electric power a predetermined frequency. The reciprocating translational motion is guided almost without friction loss.

  According to the eighth invention, in addition to the effects of the sixth or seventh invention, the ball screw can easily adjust the mass addition effect of the rotating body simply by changing the lead.

  According to the ninth aspect of the invention, in addition to the effects of any of the sixth to eighth aspects of the invention, the motor that reciprocally rotates the blade stabilizes the flutter phenomenon of the blade only by consuming a small amount of power. To give rise to.

  According to the tenth invention, in addition to the operational effects of any of the sixth to ninth inventions, even when the direction of the water flow is reversed, the flutter of the wing without changing the direction of the wing or the entire device. The phenomenon occurs stably.

  In place of conventional wind power generation and hydroelectric power generation using dams, the device of the present invention is installed in the flow of water in small rivers that are scattered in many places and capable of generating several kW and are not used at all. As a result, a considerable amount of electric power is provided as a distributed power source, and it is expected to contribute not only to energy saving but also to the suppression of carbon dioxide generation, which is said to warm the earth.

  Further, according to the tenth invention, it is possible to generate power without changing the direction of the wing or the entire apparatus even for a tidal current in which the direction of water flow is reversed. Is expected to be used.

  Hereinafter, an embodiment of the present invention will be described with reference to FIG.

In the figure, 01 is a blade that immerses in the flow of water and causes fluttering, and its chord length extends substantially along the flow of water, and its blade width extends in the water depth (vertical) direction. The posture is set. The movement of the wing 01 due to the flutter phenomenon is
(1) Reciprocating rotational motion (pitching motion) in which the blade 01 changes the angle of attack with respect to the flow.
(2) The reciprocal translational motion of the wing 01 moving across the flow is superposed. The movements of (1) and (2) are almost 90 degrees out of phase. Behaves like swimming with a twisted body. Furthermore, the power generation of the present invention utilizes the movement (2) of the above movements.

  The blade 01 is supported as follows so that a flutter phenomenon can occur in the flow of water. That is, 02 is an axis extending vertically from the upper end of the blade 01 and extending in the vertical direction. The blade 01 is reciprocally rotated (pitched) around the shaft 02 by two upper and lower bearings 03, 03. It is supported.

  Next, 04 is a rod-like reciprocating translation member that reciprocally translates in conjunction with the wing 01, and is arranged so as to cross the flow of water, and the wing 01 is connected to the bearings 03, 03 and its bearings. It is supported via a vertical flat shaft fixing seat (reference numeral omitted) for fixing 03, 03.

  Reference numerals 05 and 05 denote a pair of equal-length parallel leaf springs that directly and elastically support the reciprocating translation member 04. The reciprocating translation member 04 is linked to the blades 01 to achieve desired vibration without friction loss. It is set so that it can reciprocate in a number, and the longitudinal direction is parallel to the water flow, the width is vertical, and the shaft 02 is parallel to each other so that the blade 01 is sandwiched between them. In addition, the reciprocating translation member 04 is coupled to the respective distal ends thereof, and the respective proximal ends thereof are fixed to the frame 06. The effect will be described later.

  If the flutter phenomenon occurs in the wing 01 with the above configuration, the reciprocal translational motion can be converted into power generation. However, since the flutter phenomenon does not occur due to a lack of mass in the present invention, The mass adding mechanism 10 is added to ensure the necessary mass.

  That is, 11 is a ball screw shaft arranged in parallel to the reciprocating translation member 04, that is, a male screw portion of the ball screw, and is screwed to the female screw portion 12 that reciprocally translates in conjunction with the reciprocating translation member 04. Thereby, the reciprocating rotational motion of the blade 01 is smoothly converted into the reciprocating rotational motion of the ball screw shaft 11 via the reciprocating translation member 04 and the female screw portion 12. Reference numeral 13 denotes a bearing for supporting the non-threaded portion (reference numeral omitted) of the ball screw shaft 11.

  Next, 14 is a disk directly connected to the ball screw shaft 11, and the virtual mass of the blade 01 is necessary for the flutter phenomenon to occur by arbitrarily setting the diameter, mass, and lead of the ball screw shaft 11. It can be increased beyond a certain value. Further, the disk 14 is not limited to a circular plate, but may be a cylinder or other rotating body, and at least a part of the disk 14 can be replaced by a rotor of the generator 20 described later. The generator 20 is disposed on the tip side of the ball screw shaft 11 and on the shaft. Although not visible in the drawing, the generator 20 is directly connected to the tip of the ball screw shaft 11 and a stator surrounding the rotor (both shown). (Omitted) is built-in.

  In addition to the above configuration, at least one “torsion spring” having a restoring force for causing a reciprocating rotational motion (pitching motion) at a desired frequency is interposed in the blade 01 immersed in the water flow. In this way, one elastic support system is constituted and combined with another elastic support system corresponding to the reciprocating translational motion including the leaf springs 05 and 05, and the blade 01 is subjected to water flow. It is also possible to generate electricity by causing a flutter phenomenon.

  However, in order to cause the flutter phenomenon more stably, the following configuration is further adopted here. That is, instead of the “torsion spring”, the motor 30 is directly connected to the shaft 02, and the blade 01 is forced to reciprocate and rotate (pitching motion) at an arbitrary cycle and an arbitrary angle via the shaft 02. I tried to make it happen. In addition, the electric power for making this blade | wing 01 reciprocatingly rotate (pitching movement) is about 10% of the electric power generation amount of this apparatus.

  Even when the direction of water flow is reversed by making the blade cross-sectional shape of the blade 01 symmetric in the front-rear direction and the center of the reciprocating rotational motion (pitching motion) to be the center of the chord, On the other hand, the flutter phenomenon can occur stably.

  Here, a part of the method used for the planned design of the above apparatus will be described. The mass of the blade 01, the center of gravity (not shown), the position of the shaft 02, Parameters such as the additional mass by the mass adding mechanism 10 and the frequency ratio of the translational vibration and the pitching vibration of the blade 01 are analyzed using the potential theory for the unsteady hydraulic power of the water flow or numerical analysis of the Navier-Stokes equations. The details are omitted.

  The effect of this apparatus is demonstrated. First, an elastic support system including the leaf springs 05 and 05 corresponding to the reciprocating translational motion of the blade 01 will be described. Regardless of the flow of water, when the reciprocating translation member 04 is translated in the longitudinal direction by any means on the wing 01 or the reciprocating translation member 04, the leaf springs 05 and 05 are bent in that direction.

  When the force that bent the plate springs 05 and 05 disappears, the reciprocating translation member 04 coupled to the tip thereof has a natural period (frequency) based on the mass and the spring constant. Although it vibrates freely left and right together with the wings 01 that are interlocked with each other, its movement is gradually attenuated by a (very slight) loss caused mainly by the curvature of the leaf springs 05 and 05 and stops.

  That is, the elastic support system including the leaf springs 05 and 05 has a function of providing a restoring force for setting the frequency of the reciprocating translational motion of the blade 01 to a desired frequency, and the reciprocating translational motion without friction loss. There is a guide function that can be performed with very little damping, and both functions are very effective for the operation of the apparatus.

Next, the mass adding mechanism 10 will be described. The mass addition by the mass addition mechanism 10 is expressed by the following equation.

  For example, when a blade having a chord length of 400 mm and a blade width of 1500 mm is used as the blade 01, the blade mass needs to be about 3000 kg in order to cause the flutter phenomenon. As the disk 14 constituting the mass adding mechanism 10, for example, if a disk having a mass of 0.7 kg and a radius of 150 mm is used and the lead of the ball screw is 10 mm and the formula (1) is used, the mass addition is 3100 kg, and the flutter phenomenon It is almost equal to 3000 kg required to cause

  That is, according to the present apparatus, a flutter phenomenon occurs in the flow of water by using a 0.7 kg disk instead of a mass of 3000 kg, which is thought to be difficult to achieve with a blade having a chord length of 400 mm and a blade width of 1500 mm. .

  Next, the operation of this apparatus will be described. The wing 01 is immersed in a flow of water, the motor 30 is driven so as to have an appropriate maximum angle of attack and period according to the flow rate of the water, and the shaft 02 is moved. Forcibly, a reciprocating rotational motion (pitching motion) is performed. Along with this, a flutter phenomenon occurs stably on the blade 01 elastically supported by the leaf springs 05 and 05 via the reciprocating translation member 04 and the like.

To reiterate, (1) The reciprocating rotational motion (pitching motion) in which the blade 01 changes the angle of attack with respect to the flow.
(2) The reciprocal translational motion of the wing 01 moving across the flow is superposed. The movements of (1) and (2) are almost 90 degrees out of phase. It behaves like a swirling swim. In the present invention, the movement (2) of the above movements is used for power generation.

  As described above, a flutter phenomenon occurs in the blade 01 in a water flow that has not been predicted in the past, and the reciprocating translation of the blade 01 is linked to the reciprocating translation member 04 and the female screw portion 12. Thus, the ball screw shaft 11 and the reciprocating rotational motion of the rotor are smoothly converted, whereby the generator 20 is finally driven and converted into electric power with high efficiency.

  In addition, hydropower generation using existing propellers uses the energy of a circular cross-section that the propeller crosses the running water, whereas this device uses the energy of a rectangular cross-section where the blades 01 are reciprocally translated. Therefore, the energy of the flowing water that can be used increases, and the amount of power generation can be increased.

  Furthermore, in this device, since the other device parts and equipment except the wing 01 and a part of the shaft 02 that supports the wing are in the air and no waterproof specification is required, the reliability is increased and the maintenance management is facilitated. In addition, the present apparatus can be provided at a low cost.

  In addition, because the submerged part is only the first wing 01 and a part of the shaft 02 that supports the wing, compared with hydroelectric power generation using an existing propeller with many submerged parts, dust contained in the water flow is caught and power generation efficiency is reduced. The risk of doing so can be reduced.

  In place of conventional wind power generation and hydroelectric power generation using dams, the device of the present invention is installed in the flow of water in small rivers that are scattered in many places and capable of generating several kW and are not used at all. As a result, a considerable amount of electric power is provided as a distributed power source, and it is expected to contribute not only to energy saving but also to the suppression of carbon dioxide generation, which is said to warm the earth.

  Further, by making the blade cross-sectional shape of the blade 01 symmetrical in the front-rear direction and setting the center of the reciprocating rotational motion (pitching motion) to the center of the chord, the tidal current in which the direction of water flow reverses Since the flutter phenomenon can occur stably with respect to the wing 01 without changing the direction of the wing 01 or the entire apparatus, it is possible to generate electric power. Therefore, the apparatus of the present invention can also be used for power generation using tidal currents. Be expected.

  Here, referring to FIG. 2 and FIG. 3, an experimental apparatus that is the basis of the present invention and an experimental result thereof will be described for reference. FIG. 3 shows a photograph of FIG.

  2 and 3, the same reference numerals in FIG. 1 are used as they are for most of the members of the same type as those in FIG. 1, and descriptions thereof are omitted. Here, 40 is an electromagnetic damper that acts as a kind of generator, which generates an electric current (eddy current) in a good electric conductor that moves across a magnetic field, and generates electric power by resistance to the movement of the good electric conductor. It is something to measure. More specifically, 41 is a permanent magnet having a U-shaped cross section, and 42 is a strip-shaped metal piece that moves between the magnetic poles of the permanent magnet 41 so as to reciprocate in conjunction with the rod-like reciprocating translation member 04. It is fixed to one end of it. Reference numeral 43 denotes a load cell for measuring the resistance. In the figure, reference numeral 44 denotes a load cell for confirming addition of additional mass by the disk 14, and detailed description thereof is omitted.

1) Experimental conditions:
Wing specifications:
Chord length: 100mm
Wing width: 300 mm
Airfoil: NACA0015
Reciprocal translation part:
Natural frequency: 5.7 rad / s (0.907 Hz)
Mass: 23.6 kg (16.3 kg of which is added by the mass addition mechanism)
Pitching frequency: 6.0 rad / s (0.955 Hz)
Water flow rate: 1m / s

2) Experimental results:
The flutter phenomenon occurred according to the theory by the flow of water.
Reciprocal translational amplitude: 53mm
Power generation efficiency: 37.2%
Power generation amount: 4.4W

It is a perspective view which shows the whole structure. It is a perspective view which shows an experimental apparatus. It is a photograph of FIG.

Explanation of symbols

01 blade 02 shaft 03 bearing 04 rod-like reciprocating translation member 05 leaf spring 06 frame 10 mass adding mechanism 11 ball screw shaft 12 female screw portion 13 bearing 14 disk 20 generator 30 motor 40 electromagnetic damper 41 permanent magnet 42 strip metal piece 43, 44 load cell

Claims (10)

  Causing a flutter phenomenon to occur in a blade immersed in a flow of water, extracting a reciprocating translational motion that moves across the flow from vibrations of the blade constituting the flutter phenomenon, and converting the flutter into power. A method of converting water energy into electric power, wherein mass addition of a value necessary to cause a phenomenon is performed by converting the reciprocating translational motion into a reciprocating rotational motion of a rotating body and using the rotational inertial moment.   The method for converting water energy into electric power according to claim 1, wherein the blade is elastically supported by a leaf spring so as to be capable of reciprocating translation.   The method for converting water energy into electric power according to claim 1 or 2, wherein the reciprocating translational motion of the blade is converted into a reciprocating rotational motion of the rotating body via a ball screw.   4. The pitching motion (reciprocating rotational motion) that causes the blade to change the angle of attack with respect to the flow of the blade vibration constituting the flutter phenomenon is forcibly caused by a motor. 5. A method of converting the energy of water described in Crab into electric power.   5. The energy of water according to claim 1, wherein the cross-sectional shape of the blade is symmetrical in the front-rear direction, and the center of the pitching motion (reciprocating rotational motion) is the center of the chord. Method.   A blade that immerses in a water flow and causes flutter phenomenon, and a rotating body that reciprocally rotates in conjunction with a reciprocating translational motion that moves across the water flow among the vibrations of the blade based on the flutter phenomenon. An apparatus for converting water energy into electric power, characterized in that the rotating body is capable of securing a mass addition of a value necessary for causing the flutter phenomenon by the moment of inertia. .   The water according to claim 6, further comprising a pair of isometric parallel leaf springs that elastically support a reciprocating translation member that reciprocally translates in conjunction with the wing so that the wing can be reciprocally translated. That converts the energy of the energy into electric power.   The apparatus for converting water energy into electric power according to claim 6 or 7, further comprising a ball screw for converting the reciprocating translational motion of the blade into the reciprocating rotational motion of the rotating body.   7. A motor that forcibly causes a pitching motion (reciprocating rotational motion) that changes the angle of attack with respect to a flow of the blade vibration constituting the flutter phenomenon is provided. The apparatus which converts the energy of the water in any one of 8 into electric power. 10. The water energy according to claim 6, wherein the blade has a blade cross-sectional shape that is symmetrical in the front-rear direction and has a wing whose pitching motion (reciprocating rotational motion) is centered on the chord. Device to convert to.