JP4923245B2 - Vibration generator with fluid - Google Patents

Description

  The present invention relates to a vibration power generation apparatus using fluid, and is particularly suitable for use in an apparatus for converting natural energy such as wind power or hydraulic power into electric energy.

  Among the power generators using natural energy, wind turbine generators using wind power have made remarkable progress in both performance and price, especially in the field of large wind turbines, and have become comparable to conventional thermal power generation. Further, efficient wind turbines are being developed for small wind turbines, and wind power generators have been expected to generate power generators that do not generate greenhouse gases. On the other hand, hydroelectric power generation using hydropower with a long history is characterized by high energy density.

  By the way, when a fluid such as air or water hits the columnar body, a vortex called Karman vortex is generated behind the columnar body. Then, unstable vibration such as Karman vortex excitation and aerodynamic galloping occurs in the columnar body. Specifically, when a fluid hits a columnar body, the negative pressure generated on the rear side of the columnar body becomes asymmetrical due to the balance of the Karman vortex street, and one negative pressure becomes larger than the other negative pressure. . As a result, a pressing force is applied to the columnar body in one direction, and the columnar body swings in that direction. When the columnar body swings, the Karman vortex street changes, the negative pressure different from the previous one increases, and the pressing force acts in the opposite direction, causing the columnar body to swing in that direction. By repeating this, the columnar body vibrates in a direction orthogonal to the fluid flow direction.

Some proposals have already been made on such a power generation device using Karman vortices (see, for example, Patent Documents 1 and 2).
JP-A-8-321642 JP 2001-157433 A

  The amplitude of vibration excited in the columnar body by the Karman vortex grows to a large amplitude called rocking when the frequency matches the natural frequency of the columnar body itself, that is, the resonance frequency. However, the magnitude of the amplitude is sensitive to the velocity of the fluid, and decreases rapidly in the region where the flow velocity deviates from the resonance frequency region. Therefore, in order to efficiently extract electric energy from vibration due to Karman vortex, it is important to maintain a large amplitude within a range where the vibrating body is not broken.

  However, the conditions for the generation of Karman vortices due to fluids such as wind in nature are wide, with Reynolds number Re = u · d / v (u: flow velocity, d: diameter of cylinder, v: kinematic viscosity) being several tens to several tens of thousands. Range. On the other hand, the mechanical resonance of the vibrating body has a high Q value and a sharp peak, so that the range in which both frequencies match and maintain rocking is extremely narrow compared to the fluctuation range of the wind speed. .

  In addition, the speed of a fluid such as wind in the natural world is not always constant and fluctuates with time. Therefore, the Karman vortex frequency caused by the fluid is usually constantly fluctuating. On the other hand, since the mechanical resonance frequency of the columnar body is determined and constant from the dimensions of the columnar body, the resonance range is extremely narrow.

  Therefore, in a vibration power generation device using vibration of one columnar body arranged in a fluid, the Karman vortex frequency and the mechanical resonance frequency do not always coincide with each other, and electric energy is efficiently extracted from vibration energy. There was a problem that could not.

  As a countermeasure for this, in the invention described in Patent Document 1, a plurality of piezoelectric elements having different thicknesses are stacked so that each mechanical resonance frequency is different, but the mechanical resonance frequency of each piezoelectric element is the thickness thereof. Each is fixed. Therefore, when the Karman vortex frequency becomes a frequency other than the mechanical resonance frequency determined by the thickness of each piezoelectric element, the Karman vortex frequency and the mechanical resonance frequency do not coincide with each other. There was a problem that I could not. Further, in the invention described in Patent Document 2, the range in which the Karman vortex frequency coincides with the resonance frequency of the cylinder is expanded by changing the equivalent stiffness of the vibration cylinder in accordance with the flow velocity of the fluid. However, there is a problem that the configuration becomes complicated.

  The present invention has been made in view of such circumstances, and in a vibration power generator using fluid that converts kinetic energy of fluid into electrical energy, even if the flow velocity fluctuates over a wide range, the longitudinal vortex does not disappear, It is an object of the present invention to provide a vibration power generation apparatus that can efficiently generate power under a wide range of flow rates.

  It is another object of the present invention to provide a vibration power generator that does not require rotating parts like a power generator using a windmill or water turbine, is safe, low-cost, and has a low maintenance burden.

  According to the first aspect of the present invention, the first columnar body arranged so that the longitudinal direction intersects with the fluid flow direction and the longitudinal direction intersecting with a distance from the first columnar body. A fluid vibration power generation device comprising: a second columnar body disposed; and a power generation device disposed between the first columnar body and a mounting base.

  According to a second aspect of the present invention, in the vibration power generation apparatus using fluid according to the first aspect, the power generation apparatus is of an electromagnetic induction type.

  According to a third aspect of the present invention, in the vibration power generation apparatus using fluid according to the first aspect, the power generation apparatus is a power generation apparatus including a piezoelectric element and a pressing body that presses the piezoelectric element.

  According to a fourth aspect of the present invention, in the vibration power generation apparatus using fluid according to any one of the first to third aspects, the first columnar body is elastically supported.

  According to a fifth aspect of the present invention, in the vibration power generation apparatus using fluid according to any one of the first to fourth aspects, a gap between the first columnar body and the second columnar body is set to a fluid flow velocity. This is characterized in that it can be changed accordingly.

  According to the vibration power generation apparatus using fluid according to claim 1, the vertical vortex can be maintained even when the flow velocity of the fluid fluctuates in a wide range, and the vibration energy larger than the Karman vortex excitation can be taken out to efficiently generate power . Also, unlike the wind turbine generator and the water turbine generator, there is no need for maintenance over a long period of time because there is no rotating mechanism.

  According to the vibration power generation apparatus using fluid according to claim 2, since the main part of the power generation apparatus is composed of the magnet and the coil, it is possible to perform power generation with high reliability over a long period of time.

  According to the vibration power generation apparatus using fluid according to the third aspect, since the power generation apparatus includes the piezoelectric element and the pressing body that presses the piezoelectric element, a compact power generation apparatus can be realized.

  According to the vibration power generation apparatus using fluid according to the fourth aspect, since the first columnar body is elastically supported, the fluid energy by the vertical vortex can be easily converted into the amplitude of the columnar body.

  According to the vibration power generation apparatus using the fluid according to claim 5, the gap between the first columnar body and the second columnar body can be changed according to the flow velocity of the fluid. By selecting an appropriate gap, efficient power generation can be performed.

  Before describing the vibration power generation apparatus using fluid according to the present invention, the vertical vortex excitation found by the inventors of the present invention prior to the world will be briefly described. The longitudinal vortex excitation is arranged such that the longitudinal direction intersects with the first columnar body 1 disposed so that the longitudinal direction intersects the fluid flow direction and the first columnar body 1. In the apparatus having the second columnar body 2 provided, the distance (s) between the first columnar body 1 and the second columnar body 2 is set to the diameter (d) of the first columnar body 1. Occurs when a predetermined value is reached.

  FIG. 1 shows a first columnar body 1 arranged so that its longitudinal direction intersects with the fluid flow direction 3, and is arranged so that its longitudinal direction intersects with a distance from the first columnar body 1. 1 shows a form of a vertical vortex in an apparatus having a second columnar body 2 provided, the form shown in FIG. 1A is called a trailing vortex, and the form shown in FIG. 1B is a necklace vortex. I will call it. The trailing vortex occurs when the separation distance (s) between the first columnar body 1 and the second columnar body 2 is a small value with respect to the diameter (d) of the first columnar body 1. On the other hand, the necklace vortex is generated when the distance (s) between the first columnar body 1 and the second columnar body 2 is a relatively large value with respect to the diameter (d) of the first columnar body 1. appear. For example, the trailing vortex shown in FIG. 1A is observed in a water flow with s / d = 0.08 and a flow velocity of 12.8 cm / sec. The necklace vortex shown in FIG. 1B is observed in a water flow with s / d = 0.28 and a flow velocity of 12.5 cm / sec. Longitudinal vortices are periodically generated from the vicinity of the intersection between the first columnar body 1 and the second columnar body 2. It is observed that the vertical vortex takes two forms when the separation gap (s) between the first columnar body 1 and the second columnar body 2 is slightly changed. In addition, the excitation force generated by these two types of longitudinal vortices has a large excitation force that is more than three times the excitation force generated by the conventional Karman vortex, and the distance (s) between the two columnar bodies is slightly changed. It was found that the vibration was maintained even in a wide range of flow velocity. These two types of longitudinal vortex excitation, that is, trailing vortex excitation and necklace vortex excitation, show different forms from the conventional Karman vortex excitation.

  The vertical vortex is generated not only when the fluid is a liquid such as water but also when the fluid is a gas such as air. FIG. 2 shows a first columnar body 1 disposed so that the longitudinal direction intersects with the air flow direction, and is disposed so that the longitudinal direction intersects with a distance from the first columnar body 1. 6 is an experimental result showing a relationship between the air flow velocity and the amplitude of the first columnar body 1 in an apparatus having the second columnar body 2 formed. In the figure, the data of (1) shows the relationship of the amplitude to the vortex in a single columnar body, that is, the flow velocity by normal Karman vortex excitation. The change of the amplitude with respect to the flow velocity is extremely sensitive, and when the flow velocity fluctuates even slightly from the flow velocity corresponding to the resonance frequency, the amplitude decreases rapidly. The data of (2) shows the relationship of the amplitude to the flow velocity due to the trailing vortex excitation at s / d = 0.08. The trailing vortex excitation occurs in a region where the flow velocity is higher than that of the Karman vortex excitation, and the change in amplitude with respect to the flow velocity is insensitive. The data of (3) shows the relationship of the amplitude to the flow velocity due to necklace vortex excitation at s / d = 0.28. Necklace vortex excitation occurs in a region where the flow velocity is higher than that of trailing vortex excitation. And the change of the amplitude with respect to the flow velocity due to the necklace vortex excitation is extremely insensitive, and maintains a large value without the amplitude being attenuated in a wide flow velocity region. In the example of the figure, it can be seen that a large amplitude is maintained in a wide range of flow velocity ranging from 7.5 to 13 m / sec. From these data, it can be seen that if the necklace vortex excitation can be used for wind power generation and hydropower generation, a power generation device applicable to a wide range of wind speeds and water flow velocities can be realized.

  Hereinafter, a vibration power generation apparatus using a fluid according to the present invention will be described with reference to the drawings. FIG. 3 is a front view showing a first embodiment of the vibration power generation apparatus using fluid, and FIG. 4 is a plan view. 5 is a cross-sectional view taken along arrow AA in FIG. The present invention is arranged such that the first columnar body 1 disposed so that the longitudinal direction intersects the fluid flow direction 3 is separated from the first columnar body 1 and the longitudinal direction intersects. A second columnar body 2 provided, and a power generator 5 disposed between the first columnar body 1 and the mounting base 4 are provided.

  A support column 7 is erected on the bottom surface of the flow path through which a fluid such as water or air flows, for example, the ground surface 6. Near the upper end of the column 7, the base end portion of the first columnar body 1 is supported via an elastic body 8. The first columnar body 1 is elastically supported so as to be substantially parallel to the ground 6. Here, it is preferable to use an elastic body 8 having an anisotropic elastic coefficient. For example, the rubber 8 and the steel plate are laminated as the structure of the elastic body 8, and when the external force acts on the first columnar body 1, the horizontal rigidity is large and the vertical rigidity is small. Those having an elastic modulus of Further, an elastic body 8 configured to increase the rigidity in the horizontal direction by combining a spring having an isotropic elastic coefficient and the side plate and consequently reduce the rigidity in the vertical direction may be used.

  A mounting base 4 on which a coil 11 as a power generator is placed is fixed to the ground 6 corresponding to the tip 9 of the first columnar body 1, and a covered conductive wire is formed on the mounting base 4. A coil 11 is provided. A rod-like permanent magnet 12 is fixed to the tip of the first columnar body 1 and is suspended so as to be inserted into the central portion of the coil 11. Therefore, when the tip 9 of the first columnar body 1 vibrates in the vertical direction 13, the permanent magnet 12 is inserted into and removed from the center of the coil 11 fixed on the mounting base 4. AC power will be generated.

  On the downstream side of the first columnar body 1 arranged so that the longitudinal direction intersects the fluid flow direction 3, a second columnar body 2 is separated from the first columnar body 1. Is provided. The second columnar body 2 is erected so that the longitudinal direction intersects the first columnar body 1. Specifically, the second columnar body 2 is obtained by standing and fixing the columnar body 2 on the bottom plate 14 so that the bottom plate 14 can be fixed at an arbitrary position with respect to the ground 6. That is, in order to set the spacing (s) between the first columnar body 1 and the second columnar body 2 to a predetermined value with respect to the diameter (d) of the first columnar body 1, It is only necessary to change the position with respect to the ground 6. Therefore, the separation interval (s) between the first columnar body 1 and the second columnar body 2 is set according to the flow velocity of the fluid such as water or air in the environment where the vibration power generation apparatus according to the present invention is installed. Necklace vortex excitation can be reliably generated with s / d being an appropriate value.

  FIG. 6 is a front view showing a second embodiment of the present invention. This corresponds to FIG. 3 which is a plan view of the first embodiment. Although the basic configuration is the same as that of the first embodiment, in the first embodiment, the power generation device 5 is of an electromagnetic induction type, whereas in the second embodiment, the power generation device 5 presses the piezoelectric element 15 and the piezoelectric element 15. It differs in that it is a power generation device comprising the pressing body 16 that performs the above. A mounting base 4 on which a piezoelectric element 15 serving as a power generation device is placed is fixed to the ground 6 corresponding to the tip of the first columnar body 1, and a piezoelectric element 15 made of a piezoelectric material such as ceramics is placed on the mounting base 4. Is provided. A pressing body 16 that presses the piezoelectric element 15 is fixed to the tip of the first columnar body 1 and is in contact with or close to the upper surface of the piezoelectric element 15. Therefore, when the tip of the first columnar body 1 vibrates in the vertical direction 13, the piezoelectric element 15 is periodically pressed, and AC power is generated in the piezoelectric element 15.

  According to the vibration power generator of the first embodiment as described above, the separation gap (s) between the first columnar body 1 and the second columnar body 2 can be changed according to the flow velocity of the fluid. Therefore, by selecting the separation gap (s) that is optimal for the flow rate condition in the installation environment, even if the flow rate of the fluid fluctuates over a wide range, a vertical vortex can be reliably generated and power can be generated efficiently. Further, unlike the conventional wind turbine generator and water turbine generator, there is no need for maintenance over a long period of time because there is no rotating mechanism. Furthermore, since the main part of the power generator 5 is composed of the permanent magnet 12 and the coil 11, highly reliable power generation can be performed over a long period of time. Further, since the first columnar body 1 is elastically supported, the fluid energy due to the vertical vortex of the fluid can be easily converted into the amplitude of the columnar body 1.

  Further, according to the vibration power generator of the second embodiment, since the power generator 5 includes the piezoelectric element 15 and the pressing body 16 that presses the piezoelectric element 15, a compact power generator can be realized.

  As mentioned above, although this invention was demonstrated based on the Example, this invention can carry out various deformation | transformation implementation. For example, in the above embodiment, the first columnar body 1 and the second columnar body 2 use the columnar bodies 1 and 2 having a circular cross section, but the cross-sectional shapes of these columnar bodies 1 and 2 are limited to a circular cross section. It is not something. The cross-sectional shape may be a polygon such as a quadrangle, or a non-circular cross-sectional shape such as an ellipse. Further, both the first columnar body 1 and the second columnar body 2 may be supported at one end as in the embodiment, but may also be supported at both ends.

  Furthermore, although the case where the column 7 and the mounting base 4 are directly erected on the ground 6 has been described in the above embodiment, the column 7 and the mounting base 4 may be erected on a common base plate.

The state of a longitudinal vortex is shown, (a) shows a trailing vortex excitation, and (b) shows a necklace vortex excitation. It is a characteristic view which shows the relationship between the flow velocity of a fluid, and the amplitude of a columnar body. It is a front view which shows 1st Example of this invention. It is a top view which shows 1st Example of this invention. It is AA arrow sectional drawing in FIG. It is a front view which shows 2nd Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st columnar body 2 2nd columnar body 3 Flow direction of fluid 4 Installation stand 5 Power generator
15 Piezoelectric element
16 Pressing body

Claims (5)

A first columnar body disposed so that the longitudinal direction intersects the fluid flow direction;
A second columnar body disposed so as to intersect the longitudinal direction at a distance from the first columnar body;
A power generation device disposed between the first columnar body and the mounting base;
A vibration power generation apparatus using fluid. The vibration power generation apparatus using fluid according to claim 1, wherein the power generation apparatus is of an electromagnetic induction type. The vibration power generation apparatus using fluid according to claim 1, wherein the power generation apparatus is a power generation apparatus including a piezoelectric element and a pressing body that presses the piezoelectric element. The vibration power generation apparatus using fluid according to claim 1, wherein the first columnar body is elastically supported. 5. The vibration power generation using fluid according to claim 1, wherein a separation gap between the first columnar body and the second columnar body can be changed according to a flow velocity of the fluid. apparatus.

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