Vortex-induced vibration power generation device and vortex-induced vibration power generation system

Abstract

To provide a vortex-induced vibration power generation device that has few restrictions on size and installation location and has a simple structure, making it possible to generate power over a wide range of flow velocities, and a vortex-induced vibration power generation system using the same.SOLUTION: A vortex-induced vibration power generation device 10 constituting a vortex-induced vibration power generation system includes a hollow column 20 having an upper end (free end) and a lower end (fixed end), a transducer 30 that converts the vibration energy of the hollow column 20 into electrical energy, and a load application device 40. The load application device 40 is configured to apply a load between the upper and lower ends of the hollow column 20 from inside the hollow column 20. The load may be in a direction that draws the upper end toward the lower end, or in a direction that moves the upper end away from the lower end. When such a load is applied between the upper and lower ends, an axial force in a compressive or tensile direction acts on the hollow column 20. The structural resonance frequency of the hollow column 20 changes due to the action of this axial force.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a vortex-induced vibration power generation device that converts vibration energy obtained by vortex-induced vibration of a pillar placed in a fluid into electrical energy to generate electricity, and a vortex-induced vibration power generation system using the same. [Background technology]

[0002] When an object is placed in a fluid such as air or water, Kármán vortices may be generated behind the object in the direction of the fluid flow. However, depending on the conditions, synchronous vibrations accompanied by symmetric vortices may occur in the direction of the flow, in addition to the synchronous vibrations caused by Kármán vortices, at lower flow velocities. When the Kármán vortex shedding frequency and the object's structural resonant frequency coincide, vortex-induced vibration occurs, in which the object vibrates in sync with the Kármán vortices. Furthermore, when the structural resonant frequency and the Kármán vortex shedding frequency of a cylindrical object approach each other, the two resonant frequencies synchronize, generating Kármán vortices and causing structural vibration, a phenomenon known as lock-in. Vortex-induced vibration power generation (VIV) systems generate electricity by converting the vibrational energy of an object vibrating due to vortex-induced vibration into electrical energy. However, fluid flow velocities in nature are not necessarily constant. Therefore, to improve the power generation performance of VIV systems, a mechanism is needed to match the structural resonant frequency of the object to the Kármán vortex shedding frequency, which changes with the fluid flow velocity. A vortex-induced vibration power generation device having such a mechanism is disclosed in, for example, Patent Document 1 (Japanese Patent Laid-Open No. 2001-157433) and Patent Document 2 (Japanese Patent Laid-Open No. 2017-530675).

[0003] Patent Document 1 discloses a vortex-excited vibration power generation system (e.g., a first embodiment) in which an object (vibrator) to be vortex-excited is supported by an elastic body, and the restoring rigidity of the elastic body is changed by displacement due to the force of the fluid hitting the vibrator, thereby changing the structural resonance frequency of the vibrator in accordance with the flow velocity of the fluid. Patent Document 1 also discloses a vortex-excited vibration power generation system (e.g., a third embodiment) in which the vibrator is formed from a string-shaped member formed to bend elastically, one end of the vibrator is fixed, a movable magnet is provided at the other end, and a fixed magnet is further arranged at a position opposite the movable magnet so that the same poles face each other. In a vortex-excited vibration power generation system configured in this way, the force of the fluid causes the vibrator to bend, changing the distance between the movable magnet and the fixed magnet. This changes the tension applied to the vibrator due to the repulsive force between the movable magnet and the fixed magnet, and the structural resonance frequency of the vibrator changes in accordance with the flow velocity of the fluid. Furthermore, Patent Document 1 discloses a vortex-induced vibration power generation device (e.g., a fifth embodiment) in which both ends of a vibrating body are supported by elastic bodies (coil springs), both end faces of the vibrating body to which the elastic bodies are attached are made of elastic thin plates, and a bending member with a weight is provided in the center between the both end faces. With this configuration, the elastic body expands and contracts due to the force of the fluid hitting the vibrating body, changing the distance between the both end faces of the vibrating body. This changes the degree of bending of the bending member, changing the rotational moment of the rotational vibration of the vibrating body, and the structural resonance frequency of the vibrating body changes depending on the flow velocity of the fluid.

[0004] Patent Document 2 discloses a vortex-induced vibration power generation system in which a static structure surrounds a pole extending vertically upward from the ground, and ring-shaped magnets are attached to both the pole and the static structure. In Patent Document 2, the pole corresponds to the vibrating body in Patent Document 1. The ring-shaped magnets attached to the pole and the ring-shaped magnets attached to the static structure are arranged in a mutually repulsive orientation. With this configuration, when the pole vibrates, the magnets attached to the pole and the static structure approach each other on one side, while the distance between the magnets increases on the opposite side. Because the repulsive force between magnets is inversely proportional to the square of the distance, as the fluid flow rate increases and the vibration amplitude of the pole increases, the distance between the magnets at their closest points becomes shorter, thereby increasing the maximum repulsive force generated between the magnets. This increase in repulsive force improves the apparent rigidity, and the resonant frequency of the pole increases as the fluid flow rate increases. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-157433 [Patent Document 2] Special Publication No. 2017-530675 Summary of the Invention [Problem to be solved by the invention]

[0006] The vortex-induced vibration power generation device disclosed in Patent Document 1 has a mechanism for automatically changing the structural resonance frequency of the vibrating body in accordance with changes in the fluid flow velocity. However, the range of application of the vortex-induced vibration power generation device disclosed in Patent Document 1 is limited. For example, in the first embodiment, the upper and lower ends of the vibrating body are supported by frame-shaped supports via coil springs. This configuration makes it difficult to apply to large facilities such as wind farms, and conversely, it is difficult to miniaturize it for use as an IoT device. Furthermore, depending on the direction of the fluid flow relative to the vibrating body, the supports can affect the generation of Karman vortices, which places restrictions on installation locations.

[0007] The vortex-induced vibration power generation device disclosed in Patent Document 2 also has a mechanism that can automatically change the structural resonance frequency of the vibrating body in accordance with changes in the fluid flow velocity. However, the vortex-induced vibration power generation device disclosed in Patent Document 2 also has size limitations. For example, when this vortex-induced vibration power generation device is applied to a wind farm, the pole and the static structure surrounding the pole must be enlarged. However, as the pole becomes larger and heavier, the magnet must also be larger and stronger, but such magnets are difficult to obtain. Furthermore, since the pole must be positioned in the center of the static structure when there is no flow velocity, this vortex-induced vibration power generation device can be installed on the ground or hung down, but it is difficult to install it horizontally. In addition, the structure for arranging the magnets facing each other is complex.

[0008] The present disclosure has been made in view of the above-mentioned problems, and one objective of the present disclosure is to provide a vortex-induced vibration power generation device that has a simple structure with few restrictions on size and installation location and that is capable of generating power over a wide range of flow velocities, and a vortex-induced vibration power generation system using the same. [Means for solving the problem]

[0009] The vortex-induced vibration power generation apparatus provided in the present disclosure includes a hollow column having a free end and a fixed end, a transducer that converts the vibration energy of the hollow column into electrical energy, and a load application device that applies a load between the free end and the fixed end from inside the hollow column. The hollow column may be installed vertically, horizontally, or diagonally, as long as one end is fixed and the other end is free. The hollow column may be cylindrical or rectangular, or may have a more complex cross-sectional shape. Furthermore, the cross-section of the hollow column may have a constant shape from the free end to the fixed end, or the shape or area may change depending on the distance from the free end or the fixed end.

[0010] In one embodiment of the vortex-induced vibration power generation system, the load application device may include a linear member provided inside the hollow column and connecting the free end and the fixed end, and an actuator that pulls the linear member. A linear member refers to a member that can carry a tensile load but bends and cannot carry a compressive load. Examples of linear members include wires, ropes, chains, belts, cables, strings, and cords. The number of linear members may be one or more. The actuator may pull the linear member inside the hollow column, or may pull the linear member from inside the hollow column.

[0011] In another embodiment of the vortex-induced vibration power generation system, the load application device may include a rod member provided inside the hollow column, one end of which is fixed to the free end and the other end of which is fixed to the fixed end, and an actuator that pushes, pulls, or expands the rod member. The rod member is a rod-shaped member that can be loaded in both the tensile and compressive directions. The number of rod members may be one or more. The actuator may be one that pulls out or pushes the rod member inside the hollow column, or one that expands or contracts the rod member from inside the hollow column.

[0012] In yet another embodiment of the vortex-induced vibration power generation system, the load application device may include an inner hollow column provided inside the hollow column and having one end fixed to the free end and the other end fixed to the fixed end, and an actuator for pushing, pulling, or extending the inner hollow column. One or more inner hollow columns may be provided. The actuator may be one that extends or pushes the inner hollow column from inside the hollow column, or one that extends or retracts the inner hollow column from inside the hollow column.

[0013] In yet another embodiment of the vortex-induced vibration energy generator, the load application device may include an actuator for increasing or decreasing the pressure inside the hollow column. The interior of the hollow column may be filled with a gas or a liquid. The actuator may compress or expand a fluid inside the hollow column, or may suck or expel a fluid from or to the interior of the hollow column.

[0014] In yet another embodiment of the vortex-induced vibration power generation system, multiple types of load application devices may be combined, including a load application device consisting of a linear member and an actuator that pulls it, a load application device consisting of a rod member and an actuator that pushes and pulls or expands and contracts it, a load application device consisting of an internal hollow column and an actuator that pushes and pulls or expands and contracts it, and a load application device consisting of an actuator that increases or decreases the pressure inside the hollow column.

[0015] In one embodiment of a vortex-induced vibration power generation system provided in the present disclosure, the vortex-induced vibration power generation system includes the above-described vortex-induced vibration power generation device and a feedforward control device. The feedforward control device is configured to acquire a measured or predicted value of the flow velocity of the fluid flowing around the hollow column, and to control the load application device so as to change the load in accordance with the measured or predicted value. The relationship between the fluid flow velocity and the load may be set in advance based on the relationship between the load and the axial force generated in the hollow column, so as to obtain a desired resonant frequency in accordance with the fluid flow velocity. The vortex-induced vibration power generation system may control a plurality of vortex-induced vibration power generation devices.

[0016] In another aspect of the vortex induced vibration power generation system provided in the present disclosure, the vortex induced vibration power generation system includes the above-described vortex induced vibration power generation device and a feedback control device. The feedback control device is configured to control the load application device to change the load in accordance with the power generated by the transducer. For example, if the generated power is insufficient relative to a set value, the load may be changed so that the structural resonance frequency approaches the Karman vortex shedding frequency. Alternatively, if the generated power is in excess of the set value, the load may be changed so that the structural resonance frequency moves away from the Karman vortex shedding frequency. The vortex induced vibration power generation system may control a plurality of vortex induced vibration power generation devices.

[0017] In yet another aspect of the vortex induced vibration power generation system provided in the present disclosure, the vortex induced vibration power generation system includes the above-described vortex induced vibration power generation device, the above-described feedforward control device, and the above-described feedback control device. The vortex induced vibration power generation system may control a plurality of vortex induced vibration power generation devices. [Effects of the Invention]

[0018] According to the vortex-induced vibration power generation system provided in the present disclosure, the axial force generated in the hollow column can be changed by changing the load applied between the free end and the fixed end by the load application device. If the axial force of the hollow column changes, the structural resonance frequency of the hollow column also changes. Therefore, by appropriately adjusting the load applied by the load application device, the structural resonance frequency of the hollow column can be brought closer to the generation frequency of Kármán vortices generated around the hollow column, thereby generating vortex-induced vibration. The vibration energy of the vortex-induced vibration can then be extracted as electrical energy by a transducer. In other words, the vortex-induced vibration power generation system provided in the present disclosure is capable of generating electricity over a wide range of flow velocities.

[0019] Furthermore, in the vortex-induced vibration power generation system provided in the present disclosure, the load application device applies a load between the free end and the fixed end from inside the hollow column, thereby changing the axial force generated in the hollow column. Therefore, the presence or operation of the load application device does not affect the fluid outside the hollow column. Furthermore, because the load application device only applies a load between the free end and the fixed end from inside the hollow column, it can have a simple structure. Therefore, the vortex-induced vibration power generation system provided in the present disclosure can reduce size restrictions and installation location restrictions. Another advantage is that the load application device is located inside the system, making it easier to predict the generation of vortices compared to when it is installed externally.

[0020] According to the vortex induced vibration power generation system provided in the present disclosure, the load applied by the load application device between the free end and the fixed end of the hollow column can be controlled so that the structural resonance frequency of the hollow column approaches the generation frequency of Karman vortices generated around the hollow column, thereby enabling the vortex induced vibration power generation system to efficiently generate power over a wide range of flow velocities. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a diagram showing the overall configuration of a vortex-induced vibration power generation apparatus according to an embodiment of the present disclosure. FIG. [Figure 2]10A and 10B are diagrams showing modified shapes of hollow columns. [Figure 3] 10A and 10B are diagrams showing modified shapes of hollow columns. [Figure 4] FIG. 2 is a diagram illustrating the function of a load application device. [Figure 5] 10A and 10B are diagrams illustrating a method for causing a vortex-induced vibration power generation device to generate power when the flow velocity is low and the vortex-induced vibration generation frequency is low. [Figure 6] 10A and 10B are diagrams illustrating a method for causing a vortex-induced vibration power generation device to generate power when the flow velocity is high and the vortex-induced vibration generation frequency is high. [Figure 7] 1A and 1B are diagrams illustrating the configuration and operation of a first embodiment of a load application device. [Figure 8] 10A and 10B are diagrams illustrating the configuration and operation of a second embodiment of a load application device. [Figure 9] 10A and 10B are diagrams illustrating the configuration and operation of a third embodiment of a load application device. [Figure 10] 10A and 10B are diagrams illustrating the configuration and operation of a fourth embodiment of a load application device. [Figure 11] 1 is a diagram showing a configuration of a vortex-induced vibration power generation system according to a first embodiment of the present disclosure. FIG. [Figure 12] FIG. 2 is a diagram showing a control flow of the vortex-induced vibration power generation system according to the first embodiment of the present disclosure. [Figure 13] FIG. 10 is a diagram showing the configuration of a vortex-induced vibration power generation system according to a second embodiment of the present disclosure. [Figure 14] FIG. 10 is a diagram showing a control flow of a vortex-induced vibration power generation system according to a second embodiment of the present disclosure. [Figure 15] FIG. 10 is a diagram showing the configuration of a vortex-induced vibration power generation system according to a third embodiment of the present disclosure. [Figure 16] FIG. 10 is a diagram showing a control flow of a vortex-induced vibration power generation system according to a third embodiment of the present disclosure. [Figure 17] FIG. 1 is a diagram showing an example of the configuration of a vortex-induced vibration power generation system. [Figure 18] FIG. 10 is a diagram showing another example of the configuration of a vortex-induced vibration power generation system. [Figure 19]This figure shows the relationship between the load and natural frequency applied by a wire-type load application device (hollow plastic cylinder, nylon wire), comparing experimental data, calculated values ​​using a theoretical formula, and analytical values ​​using the finite element method. [Figure 20] 1 is a graph obtained by non-dimensionalizing each parameter of a theoretical formula for the relationship between the load applied by a wire-type load application device and the natural frequency. [Figure 21] This is a graph obtained by non-dimensionalizing each parameter in the theoretical formula for the relationship between the load and natural frequency applied by rod-type, double-cylinder-type, and pressure-type load application devices. [Figure 22] FIG. 10 is a diagram showing the results of an analysis using the finite element method on the relationship between the load applied by a rod-type load application device and the natural frequency. [Figure 23] FIG. 10 is a diagram showing the results of an analysis using the finite element method on the relationship between the load applied by a double-cylinder load application device and the natural frequency. [Figure 24] FIG. 10 is a diagram showing the results of an analysis using the finite element method on the relationship between the load applied by the pressure-type load application device and the natural frequency. DETAILED DESCRIPTION OF THE INVENTION

[0022] 1. Vortex-induced vibration power generation device 1-1. Embodiment of vortex-induced vibration power generation device 1-1-1. Overall configuration of the vortex-induced vibration power generation device An embodiment of a vortex-induced vibration power generation device provided in the present disclosure will be described below. First, the overall configuration of the vortex-induced vibration power generation device will be described with reference to FIG.

[0023] The vortex-induced vibration power generation system 10 includes a long hollow column 20 as a vibrating body. The hollow column 20 is a cylinder with a hollow interior 21. The hollow column 20 stands facing upward from a base 50. The lower end 23 of the hollow column 20 is a fixed end fixed to the base 50, and the upper end 22 is an unconstrained free end. The hollow column 20 is placed in a fluid. For example, the hollow column 20 may be placed in air with a flow, or in a liquid with a flow. Furthermore, when the hollow column 20 is placed in a liquid, it does not necessarily have to be entirely submerged in the liquid; the upper end may protrude into the air, or only the upper end may be submerged in the liquid.

[0024] The hollow pole 20 can be made of, for example, iron or steel materials such as steel, light metals such as aluminum, reinforced concrete, resins such as nylon or polyamide, elastomers, fiber-reinforced composite materials, or natural materials such as bamboo. The material to be used can be determined according to desired requirements such as the size and weight of the hollow pole 20, the environment in which the hollow pole 20 will be installed, and the power supply target. The hollow pole 20 may also be made of multiple types of materials, such as making the base of the hollow pole 20 out of reinforced concrete and the tip out of a composite material.

[0025] The size of the hollow column 20 may be determined depending on the application of the vortex excited vibration power generation apparatus 10. Because there are few size restrictions on the vortex excited vibration power generation apparatus 10, the vortex excited vibration power generation apparatus 10 can be applied to a variety of applications. For example, the vortex excited vibration power generation apparatus 10 can be configured as a small power supply for supplying power to a microcomputer, IoT device, etc. In that case, the size of the hollow column 20 will be approximately 10 to 30 cm. The vortex excited vibration power generation apparatus 10 can also be configured as a power generation apparatus to be installed on the roof of an office building, etc. In that case, the size of the hollow column 20 will be in the 2 meter range. Furthermore, the vortex excited vibration power generation apparatus 10 can also be configured as a large power generation facility such as a wind farm. In that case, the size of the hollow column 20 will be in the 10 meter range.

[0026] The base 50 may have any shape and material that can stably support the hollow columns 20. For example, if the hollow columns 20 are large structures, the base 50 may be a foundation structure made of concrete, such as a pile foundation. Furthermore, if the vortex-induced vibration power generation apparatus 10 is installed offshore, the base 50 may be a floating structure. Furthermore, depending on the type of power supply target that receives power from the vortex-induced vibration power generation apparatus 10, the power supply target itself may serve as the base 50, and the hollow columns 20 may be attached to the power supply target. The vortex-induced vibration power generation apparatus 10 can be installed in a variety of locations. For example, the vortex-induced vibration power generation apparatus 10 can be installed on remote islands, mountainous areas, coastal areas, bridges, along roads where vehicles travel, farmland, building rooftops, marine aquaculture facilities, factory exhaust ducts, power plant cooling towers, large pipes, dam spillways, houses, observation balloons, ships, rivers, and the ocean. Furthermore, the vortex-induced vibration power generation apparatus 10 does not need to be completely fixed to one installation location, but can be portable for use in emergencies, events, etc.

[0027] The base 50 is provided with a transducer 30. More specifically, the transducer 30 is provided at the installation portion of the hollow column 20 and connected to the hollow column 20. The transducer 30 is a device that converts vibration energy generated in the hollow column 20 into electrical energy. For example, the piezoelectric effect, electromagnetic induction, electrostatic induction, or inverse magnetostriction effect can be used to generate power using the transducer 30. The means to be used can be selected appropriately depending on the power generation scale of the vortex-induced vibration power generation device 10, the frequency of the vortex-induced vibration generated in the hollow column 20, and the size of the vortex-induced vibration power generation device. Although not shown, a battery or transformer for storing the power generated by the transducer 30 can also be provided on the base 50.

[0028] Vortex-induced vibration of the hollow column 20 is caused by the fluid flowing around the hollow column 20. More specifically, when the fluid hits the hollow column 20, Karman vortices are generated behind it. Then, when the Karman vortex generation frequency matches the structural resonance frequency of the hollow column 20 itself, or approaches it, the hollow column 20 vibrates due to vortex-induced vibration due to the lock-in phenomenon. However, although the Karman vortex generation frequency changes depending on the flow velocity, the flow velocity of the fluid flowing around the hollow column 20 is not necessarily constant. For this reason, in order to extract electrical energy from the vibration of the hollow column 20, a mechanism is needed to actively or passively change the structural resonance frequency of the hollow column 20.

[0029] The vortex-induced vibration power generation system 10 includes a load application device 40 as a mechanism for actively changing the structural resonance frequency of the hollow column 20. The load application device 40 is a device that applies a load between the upper end 22 and the lower end 23 of the hollow column 20 from the inside 21 of the hollow column 20. The load applied between the upper end 22 and the lower end 23 of the hollow column 20 changes the structural resonance frequency of the hollow column 20. The specific configuration of the load application device 40 will be described later.

[0030] 1-1-2. Modifications and other configurations The overall configuration of the vortex-induced vibration power generation system 10 described above is merely one embodiment, and modifications can be made. FIG. 2 shows modified shapes of the hollow column 20. The cross-sectional shape of the hollow column can be an N-sided polygonal cross-section (N is a natural number greater than or equal to 3). For example, a rectangular cross-section such as hollow column (rectangular cross-section) 20A shown in FIG. 2A may be used. Furthermore, a cross-sectional shape other than a convex hull can also be used. For example, an H-shaped cross-section such as hollow column (H-shaped cross-section) 20B shown in FIG. 2B may be used. Furthermore, although not shown, a hydrodynamically optimized shape such as an airfoil shape can also be used. The shape of the hollow column may be one that actively induces vortex-induced vibration, or one that does not induce vortex-induced vibration more than necessary.

[0031] The cross section of the hollow column does not need to be constant in the longitudinal direction. For example, it may have a tapered shape that narrows toward the tip like an aircraft wing, or a tapered shape that widens to optimize vibration characteristics. The tip of the hollow column may also be bent to reduce noise. For example, a winglet may be provided like an aircraft wing. Furthermore, the hollow column may be provided with a splitter, vortex generator, spoiler, tip vane, or other aerodynamic devices to control vortex-induced vibration. Furthermore, the hollow column does not have to be a single column. For example, it may have an H-shaped structure in which two columns are connected in the center, or a portal-shaped structure in which two columns are connected at their tips.

[0032] As shown in Figure 3, a large diameter section 25 having an outer diameter larger than that of the hollow column 20 may be provided. The large diameter section 25 may be provided in a portion of the hollow column 20 in the longitudinal direction, or may be provided over the entire column. By increasing the outer diameter of the portion that the fluid hits, it becomes possible to optimize the Strouhal number and Reynolds number, which will be described later. The shape of the large diameter section 25 may be not only circular as shown in Figure 2, but also rectangular or H-shaped.

[0033] It is desirable to provide appropriate measures for the hollow columns depending on the installation location, such as protection against lightning (by earthing), bird strikes (by designing them with raptor eyes), protection against deposits such as volcanic ash and snow, thermal stress due to solar radiation and temperature changes, icing, adhesion of marine organisms, and salt damage. Access holes may also be provided for inspecting or replacing the internal structure of the hollow columns. The location and size of the access holes can be determined according to the size of the hollow columns. Furthermore, monitoring test specimens may be installed in the hollow columns to inspect for fatigue failure and perform health monitoring using the monitoring test specimens.

[0034] 1-2.Outline of the load application device The load application device 40 will be outlined with reference to FIGS. 4A and 4B. FIG. 4 is a diagram illustrating the function of the load application device 40. As shown in FIG. 4A, the load application device 40 can apply an inward load between the upper end 22 and the lower end 23 of the hollow column 20. This inward load generates an axial force in the compressive direction in the hollow column 20. The load application device 40 can adjust the magnitude of the inward load, thereby adjusting the magnitude of the axial force in the compressive direction. Also, as shown in FIG. 4B, the load application device 40 can apply an outward load between the upper end 22 and the lower end 23 of the hollow column 20. This outward load generates an axial force in the tensile direction in the hollow column 20. The load application device 40 can adjust the magnitude of the outward load, thereby adjusting the magnitude of the axial force in the tensile direction.

[0035] By controlling the load applied by the load application device 40 and changing the axial force generated in the hollow column 20, it is possible to change the structural resonance frequency of the hollow column 20. An example is shown below. The partial differential equation shown in Equation 1 is a vibration equation for the beam of the hollow column 20 taking the axial force into consideration.

number

[0036] When solving Equation 1 for the structural resonant frequency (natural frequency) using several assumptions, the structural resonant frequency taking into account the axial force is obtained as shown in Equation 2 below. At this time, it can be seen that the structural resonant frequency fluctuates depending on the buckling load and axial force values ​​according to Euler's equation.

number

[0037] The symbols used in Equation 1 and Equation 2 mean: ρ: material density, A: cross-sectional area, w: deflection, x: position, t: time, P: axial force, E: Young's modulus of material, I: moment of inertia of hollow column, L: length of hollow column, i: mode number, f i :i-order structure resonance frequency, λ i: ith mode coefficient, k: buckling coefficient. However, the vibration equation of a beam may include not only bending but also torsional vibration and their coupling. Next, we show the dimensionless numbers related to the motion of the fluid.

[0038] The following equation (3) is the Reynolds number. The Reynolds number is a dimensionless number that indicates the relationship between the inertial force and viscous force of a fluid.

number

[0039] The following equation 4 is the Strouhal number. The Strouhal number is a dimensionless number that indicates the relationship between the local flow velocity and the flow-average velocity in a fluid phenomenon.

number

[0040] The symbols used in Equation 3 and Equation 4 mean: D: characteristic length (outer diameter of hollow column), U: flow velocity, ν: kinematic viscosity, f k : Kármán vortex shedding frequency. When a structure exists in the flow and the cross section of the hollow cylinder 20 is circular, the Reynolds number shown in Equation 3 is 5.0 × 10 2 ~2.0×10 5 Furthermore, when the Strouhal number shown in Equation 4 is about 0.15 to 0.20, Karman vortices are generated. At this time, f calculated from Equation 4 k is the Karman vortex shedding frequency.

[0041] According to the above formula 2, when a compressive axial force P (negative value) is applied to the hollow column 20, the structural resonance frequency f iTherefore, as shown in the graph of the calculation example in Figure 5, if the structural resonance frequency is higher than the Kármán vortex shedding frequency (hereinafter and in the figure, the frequency of vortex-induced vibration that occurs when Kármán vortices are generated and match the structural resonance frequency is referred to as the vortex-induced vibration shedding frequency), an inward load can be generated by the load application device 40 to apply a compressive axial force to the hollow column 20. Note that the flow velocity is assumed to change every hour. This reduces the structural resonance frequency and brings it closer to the vortex-induced vibration shedding frequency, making power generation by vortex-induced vibration possible. In addition, the load that can be output must be controlled according to the structural strength, safety factor, and operating conditions. The latter region of Figure 5 is an example in which the load is kept constant because the flow velocity is low and vortex-induced vibration will not occur unless excessive axial force is applied.

[0042] On the other hand, according to the above formula 2, when a tensile axial force P (positive value) is applied to the hollow column 20, the structural resonance frequency f i increases. Therefore, as shown in the graph of the calculation example in Figure 6, if the structural resonance frequency is lower than the vortex-induced vibration occurrence frequency, an outward load can be generated by the load application device 40 to apply a tensile axial force to the hollow column 20. Note that the time change in flow velocity is assumed to be every hour. This increases the structural resonance frequency, bringing it closer to the vortex-induced vibration occurrence frequency, making it possible to generate power using vortex-induced vibration. Furthermore, as with compression, it is necessary to control the load that can be output depending on the structural strength, safety factor, and operating conditions. The first and second half of Figure 6 show an example in which the load is kept constant because the vortex-induced vibration occurrence frequency is high and vortex-induced vibration will not occur unless excessive axial force is applied.

[0043] 1-3. Details of the load application device 1-3-1. First embodiment 7 is a diagram showing the configuration and operation of a first embodiment of a load application device. The load application device 410 of the first embodiment includes a wire 411 as a linear member and a winder 412. The wire 411 is provided inside the interior 21 of the hollow column 20, and one end is fixed to the upper end 22 of the hollow column 20. The other end of the wire 411 is attached to the winder 412. The winder 412 is fixed to the lower end 23 of the hollow column 20. As a result, the upper end 22 and the lower end 23 of the hollow column 20 are connected by the wire 411 via the winder 412.

[0044] The winding machine 412 is an actuator that pulls the wire 411. Specifically, an electric motor (servo motor) or hydraulic motor that can rotate in both directions can be used as the winding machine 412. When the wire 411 is wound by the winding machine 412, the wire 411 is pulled as shown in FIG. 7(A), and an inward load is applied between the upper end 22 and the lower end 23 of the hollow column 20. This inward load causes an axial force in the compressive direction to act on the hollow column 20. On the other hand, when the winding machine 412 is rotated in the direction opposite to the winding direction, the wire 411 relaxes as shown in FIG. 7(B), and the inward load that was applied between the upper end 22 and the lower end 23 of the hollow column 20 decreases or disappears. As a result, the axial force in the compressive direction that was acting on the hollow column 20 also decreases or disappears.

[0045] In Fig. 7, the winding machine 412 is attached to the underside of the lower end 23 of the hollow column 20, but the actuator for the load application device 410 may be provided inside 21 of the hollow column 20. In other words, the actuator may be one that pulls out the wire 411 from inside 21 of the hollow column 20 as shown in Fig. 7, or one that pulls the wire 411 inside 21 of the hollow column 20. Also, a pulley may be provided inside 21 of the hollow column 20, and the wire 411 may be wound around the pulley to pull the wire 411.

[0046] As the actuator for the load application device 410, a cylinder capable of bidirectional multi-stage positioning or continuous positioning can be used instead of the winding machine 412. The cylinder may be an electric cylinder or a hydraulic cylinder. The tension of the wire 411 can be controlled by fixing the wire 411 to the tip of the cylinder and controlling the position of the cylinder. Alternatively, the wire 411 may be fixed to the tip of a shaft that is pushed / pulled or extended by an electric motor, and the tension of the wire 411 can be controlled by the amount of pushing / pulling or extension of the shaft.

[0047] The wire 411 can be made of synthetic fibers (carbon fiber, nylon, aramid fiber, boron fiber, etc.), glass fiber, natural fiber, elastomer, or metal. The wire 411 may be in the form of a string, a sling, or a chain. Any material or form may be selected that can withstand the tension required when the winding machine 412 is operated to pull the wire 411.

[0048] Alternatively, the wire 411 may be composed of multiple unbraided wires. When the wire 411 is subjected to a load, the amount of expansion and contraction of all of the multiple wires constituting the wire 411 is the same. For example, consider the case where the wire 411 is composed of two wires, Wire A and Wire B. In this case, the material and cross-sectional area are selected so that Wire A will not break and Wire B will break when the wire 411 is expanded by the maximum load output by the load application device, taking into account the safety factor and operating conditions. By designing in this way, a system can be constructed that detects the breakage of Wire B and stops or reduces the output of the actuator, allowing it to be used as a safety device. Furthermore, the material and cross-sectional area of ​​Wire A must be set so that it will not break even if Wire B breaks and the load applied to Wire A increases. This is to prevent the elastic energy stored in the hollow column from being released all at once. As long as the above relationship is maintained, the number and type of wires may be two or more. For example, if there are multiple wires A and one wire B, the load applied by wire B is distributed among the multiple wires A, which is preferable because it reduces the possibility of all multiple wires A breaking at the same time. Alternatively, the multiple wires A can be configured as wires A1, A2, and A3, each made of a different material and with a different cross-sectional area, and wire A1 breaks first when the load applied by wire B is distributed, and then wire A2 breaks when the load applied by wire A1 is also distributed. By designing wires 411 to break in stages, it becomes possible to release the elastic energy of hollow column 20 in stages. Such a design can prevent abrupt changes in the actuator's output and prevent damage.

[0049] As the linear member for the load application device 410, a rope, chain, belt, cable, etc. can be used instead of the wire 411. The number of linear members may be one or more. However, it is preferable that the load capacity of the linear member is less than the buckling load of the hollow column 20. By designing it in this way, even if the control of the actuator becomes unstable and a load greater than the buckling load of the hollow column 20 is output, the linear member will break first, preventing catastrophic damage due to buckling of the hollow column 20.

[0050] 1-3-2. Second embodiment 8 is a diagram showing the configuration and operation of a second embodiment of a load application device. A load application device 420 of the second embodiment includes a rod 421 as a rod member and a worm gear 422. The rod 421 is provided inside 21 of the hollow column 20, and one end is fixed to the upper end 22 of the hollow column 20. A worm of a worm gear 422 is formed at the lower end of the rod 421. A worm wheel of the worm gear 422 is fixed to the lower end 23 of the hollow column 20. As a result, the upper end 22 and the lower end 23 of the hollow column 20 are connected by the rod 421 via the worm gear 422.

[0051] The worm gear 422 is an actuator that pushes and pulls or expands and contracts the rod 421. Specifically, an electric motor (e.g., a servo motor, an AC motor, etc.) that can rotate in both directions is attached to the worm wheel. When the worm gear 422 is rotated forward, the rod 421 is pulled outward from the interior 21 of the hollow column 20 as shown in FIG. 8(A), and an inward load is applied between the upper end 22 and the lower end 23 of the hollow column 20. This inward load can apply a compressive axial force to the hollow column 20. On the other hand, when the worm gear 422 is rotated backward, the rod 421 is pushed outward toward the interior 21 of the hollow column 20 as shown in FIG. 8(B), and an outward load is applied between the upper end 22 and the lower end 23 of the hollow column 20. This outward load can apply a tensile axial force to the hollow column 20.

[0052] 8, the worm gear 422 is attached to the underside of the lower end 23 of the hollow column 20, but the actuator for the load application device 420 may be provided inside 21 of the hollow column 20. In other words, the actuator may be one that pushes, pulls, or expands the rod 421 outside the hollow column 20 as shown in FIG. 8, or one that pushes, pulls, or expands the rod 421 inside 21 of the hollow column 20.

[0053] As the actuator for the load application device 420, a cylinder capable of bidirectional multi-stage positioning or continuous positioning can be used instead of the worm gear 422. The cylinder may be an electric cylinder or a hydraulic cylinder. By fixing a rod 421 to the tip of the cylinder and controlling the position of the cylinder, it is possible to control the amount of pushing and pulling or expansion of the rod 421 inside the hollow column 21, and thus to control the load applied between the upper end 22 and the lower end 23 of the hollow column 20.

[0054] There may be multiple rods 421 provided inside 21 of hollow column 20. Furthermore, the rod members for load application device 420 may be N-sided square rods (N is a natural number of 3 or more) or rods with an H-shaped cross section. Examples of materials for the rod members for load application device 420 include metal and resin. However, it is preferable that the tensile load capacity of the rod members is less than the buckling load of hollow column 20, and the buckling load of the rod members is less than the tensile load of hollow column 20, so that the rod members break before the hollow column 20 when a load is applied.

[0055] 1-3-3. Third embodiment 9 is a diagram showing the configuration and operation of a third embodiment of a load application device. A load application device 430 of the third embodiment includes an internal hollow column 431 and a cylinder 432. The internal hollow column 431 is provided in the interior 21 of the hollow column 20, and one end is fixed to the upper end 22 of the hollow column 20. The lower end of the internal hollow column 431 is fixed to the tip of the movable part of the cylinder 432. The cylinder 432 is fixed to the lower end 23 of the hollow column 20. As a result, the upper end 22 and the lower end 23 of the hollow column 20 are connected by the internal hollow column 431 via the cylinder 432.

[0056] The cylinder 432 is an actuator that pushes, pulls, or extends / contracts the internal hollow column 431. Specifically, the cylinder 432 is an electric cylinder capable of multi-stage positioning and continuous positioning. However, the cylinder 432 may also be a hydraulic cylinder. When the movable part of the cylinder 432 is retracted, the internal hollow column 431 is pulled outward from the interior 21 of the hollow column 20 as shown in FIG. 9(A), and an inward load is applied between the upper end 22 and the lower end 23 of the hollow column 20. This inward load can apply a compressive axial force to the hollow column 20. On the other hand, when the movable part of the cylinder 432 is extended, the internal hollow column 431 is pushed outward toward the interior 21 of the hollow column 20 as shown in FIG. 9(B), and an outward load is applied between the upper end 22 and the lower end 23 of the hollow column 20. This outward load can apply a tensile axial force to the hollow column 20.

[0057] 9, the cylinder 432 is attached to the underside of the lower end 23 of the hollow column 20, but the actuator for the load application device 430 may be provided inside 21 of the hollow column 20. A worm gear can also be used as the actuator for the load application device 430 instead of the cylinder 432. By fixing the inner hollow column 431 to the tip of a shaft and controlling the amount of pushing / pulling or expansion of the shaft with the worm gear, it is possible to control the amount of pushing / pulling or expansion of the inner hollow column 431 in the inside 21 of the hollow column 20, and ultimately to control the load applied between the upper end 22 and the lower end 23 of the hollow column 20.

[0058] A plurality of internal hollow columns 431 may be provided in the interior 21 of the hollow column 20. That is, multiple internal hollow columns may be provided. Furthermore, the internal hollow column for the load application device 430 may be an N-sided hollow rectangular column (N is a natural number of 3 or more) having a space inside, or a hollow cylinder. Examples of materials for the internal hollow column for the load application device 430 include light metal, steel, reinforced concrete, resin, elastomer, fiber-reinforced composite material, and natural materials. The material of the internal hollow column may be the same as that of the hollow column 20. The tensile load capacity of the internal hollow column is preferably less than the buckling load of the hollow column 20, and the buckling load of the internal hollow column is preferably less than the tensile load capacity of the hollow column 20.

[0059] 1-3-4. Fourth embodiment 10 is a diagram showing the configuration and operation of a fourth embodiment of a load application device. A load application device 440 of the fourth embodiment is a fluid pump. The fluid pump 440 is fixed to the lower end 23 of the hollow column 20, and a suction / discharge port 441 of the fluid pump 440 opens into the interior 21 of the hollow column 20. The hollow column 20 may be provided with a valve that can be opened in an emergency to reduce the internal pressure to atmospheric pressure. The interior 21 of the hollow column 20 may be filled with liquid.

[0060] The fluid pump 440 is an actuator that increases or decreases the pressure inside the hollow column 20. Specifically, the fluid pump 440 is a pump that can both suck and discharge fluid, such as a diaphragm pump. Alternatively, the fluid pump 440 may be composed of a suction pump and a discharge pump. When the fluid pump 440 sucks in the internal fluid, the pressure inside the hollow column 20 is reduced as shown in FIG. 10(A), and an inward load is applied between the upper end 22 and the lower end 23 of the hollow column 20. This inward load can apply a compressive axial force to the hollow column 20. On the other hand, when the fluid pump 440 discharges the internal fluid, the pressure inside the hollow column 20 is increased as shown in FIG. 10(B), and an outward load is applied between the upper end 22 and the lower end 23 of the hollow column 20. This outward load can apply a tensile axial force to the hollow column 20.

[0061] 1-3-5. Other embodiments The load application devices of the first to fourth embodiments described above can also be combined and implemented, i.e., any two, three, or all of the load application device 410 of the first embodiment, the load application device 420 of the second embodiment, the load application device 430 of the third embodiment, and the load application device 440 of the fourth embodiment can be combined to apply a load to one hollow column 20.

[0062] 2. Vortex-induced vibration power generation system 2-1. First embodiment A description will be given of a vortex-induced vibration power generation system that uses the above-described vortex-induced vibration power generation device 10. First, the vortex-induced vibration power generation system according to the first embodiment will be described with reference to FIGS.

[0063] FIG. 11 is a diagram showing the configuration of a vortex-induced vibration power generation system 101 according to the first embodiment. The vortex-induced vibration power generation system 101 is a system configured to control the vortex-induced vibration power generation device 10 by feedforward control. The vortex-induced vibration power generation system 101 includes the vortex-induced vibration power generation device 10, a sensor 110, and a control device 111. As one example, the control device 111 can be provided on the base 50 together with the transducer 30, the load application device 40, and the sensor 110. However, it is also possible to provide the control device 111 in a location away from the base 50 and connect the control device 111 to the load application device 40 by wire or wirelessly. In addition, the power supply target 100 is assumed to be a transformer, a battery, or a device that consumes power.

[0064] The sensor 110 is a sensor that measures the physical quantity of the fluid. Examples of the sensor 110 that can be used include a wind direction sensor, a flow rate sensor, a temperature sensor, a humidity sensor, and a flow velocity sensor. The sensor 110 may be installed near the vortex-induced vibration power generation system 10 or at a location far away from the vortex-induced vibration power generation system 10. The sensor 110 only needs to be able to measure or predict a physical quantity, such as the flow velocity of the fluid flowing around the hollow column 20. Therefore, a weather forecast system that can obtain meteorological information about the area around the vortex-induced vibration power generation system 10 can also be used as the sensor 110. In addition, in a system in which weather forecasts are manually input, the measured or predicted flow velocity value obtained by the sensor 110 is input to the control device 111 as feedforward information FF.

[0065] The control device 111 is a microcomputer or industrial computer, and executes feedforward control according to a program. In other words, the control device 111 is configured as a feedforward control device. In the program, the relationship between the feedforward information FF input from the sensor 110 and the actuator operation amount IN of the load application device 40 is defined in advance. More specifically, the actuator operation amount IN is defined in advance so that the power generation amount Pout (or other electrical physical amount may be used; the same applies below) by the transducer 30 is maximized or optimized for the feedforward information FF. The feedforward information FF may include electrical physical amounts related to power generation, information on the power supply target, and health monitoring values ​​of the power generation device.

[0066] Fig. 12 is a diagram showing the control flow of the vortex induced vibration power generation system 101. First, in step S101, a physical quantity, represented by the flow velocity of the fluid, is measured by the sensor 110. Then, in step S102, the actuator operation amount of the load application device 40 is determined based on the measurement result (or prediction result) of the flow velocity, and the load applied from the interior 21 of the hollow column 20 between the upper end 22 and the lower end 23 is changed. Control of the load by changing the actuator operation amount may be inching control. Then, by changing the load, the structural resonance frequency of the hollow column 20 changes, and when it matches or approaches the vortex induced vibration generation frequency, vortex induced vibration occurs, and power generation by the transducer 30 becomes possible.

[0067] Note that an actual value obtained from past history may be used as a predicted value of the flow velocity of the fluid flowing around the hollow column 20. For example, in cases where it is known from the history of actual values ​​that the flow velocity of the fluid varies depending on the time of day and the flow velocity is approximately the same depending on the season, operating conditions, and time of day, feedforward control can be performed without using the sensor 110.

[0068] 2-2. Second embodiment Next, a vortex-induced vibration power generation system according to a second embodiment will be described with reference to FIGS. 13 and 14. FIG.

[0069] FIG. 13 is a diagram showing the configuration of a vortex-induced vibration power generation system 102 according to the second embodiment. The vortex-induced vibration power generation system 102 is configured to control the vortex-induced vibration power generation device 10 by feedback control. The vortex-induced vibration power generation system 102 includes the vortex-induced vibration power generation device 10, a sensor 110, and a control device 112. As one example, the control device 112 can be mounted on the base 50 together with the transducer 30, the load application device 40, and the sensor 110. However, the control device 112 can also be mounted in a location away from the base 50 and connected to the load application device 40 by wire or wirelessly. The configuration and function of the sensor 110 are the same as those of the vortex-induced vibration power generation system 101, and therefore a description thereof will be omitted. The power supply target 100 is assumed to be a transformer, a battery, or a device that consumes power.

[0070] The control device 112 is a microcomputer or industrial computer that performs feedback control according to a program. In other words, the control device 112 is configured as a feedback control device. The program acquires the power generation amount Pout by the transducer 30 or a physical quantity related thereto as feedback information FB. Then, a correction amount for the actuator operation amount IN is calculated based on the feedback information FB so that the power generation amount Pout by the transducer 30 is maximized or optimized. For example, if the power generation amount Pout is insufficient relative to the set value, a correction amount for the actuator operation amount IN is calculated so that the structural resonance frequency approaches the vortex-induced vibration occurrence frequency. Conversely, if the power generation amount Pout is excessive relative to the set value, a correction amount for the actuator operation amount IN is calculated so that the structural resonance frequency moves away from the vortex-induced vibration occurrence frequency. The feedback information FB may also include electrical physical quantities related to power generation, information on the power supply target, and health monitoring values ​​for the power generation device.

[0071] 14 is a diagram showing the control flow of the vortex-induced vibration power generation system 102. First, in step S201, a physical quantity, typified by the flow velocity of a fluid, is measured by the sensor 110. The measurement result of the physical quantity measured in step S201 is used in step S202.

[0072] In step S202, the actuator operation amount of the load application device 40 is determined based on the measurement results of the physical quantities measured in step S201 and the feedback information FB obtained in step S203. Then, the load applied between the upper end 22 and the lower end 23 from the inside 21 of the hollow column 20 is changed. The change in load changes the structural resonance frequency of the hollow column 20, and when it matches or approaches the vortex-induced vibration generation frequency, vortex-induced vibration occurs, and power generation by the transducer 30 becomes possible.

[0073] In step S203, a correction amount for the actuator operation amount for adjusting the power generation amount is calculated based on the power generation amount by the transducer 30 or a physical quantity related to it. For example, PI control or PID control may be used to calculate the correction amount. Physical quantities related to the power generation amount include, for example, the axial force generated in the hollow column 20 and the vibration acceleration of the structure due to vortex-induced vibration. The axial force can be measured by an axial force sensor, and the vibration acceleration can be measured by an acceleration sensor. Note that information obtained from the axial force sensor, acceleration sensor, and fluid sensor group can also be used for environmental sensing of the vortex-induced vibration power generation device 10.

[0074] 2-3. Third embodiment Next, a vortex-induced vibration power generation system according to a third embodiment will be described with reference to FIGS. 15 and 16. FIG.

[0075] FIG. 15 is a diagram showing the configuration of a vortex-induced vibration power generation system 103 according to the third embodiment. The vortex-induced vibration power generation system 103 is configured to control the vortex-induced vibration power generation device 10 using feedforward control and feedback control. Unlike the second embodiment, the vortex-induced vibration power generation system 103 can turn on and off the feedback control system as needed. The vortex-induced vibration power generation system 103 includes the vortex-induced vibration power generation device 10, a sensor 110, and a control device 113. As an example, the control device 113 can be mounted on the base 50 together with the transducer 30, the load application device 40, and the sensor 110. However, the control device 113 can also be mounted in a location away from the base 50 and connected to the load application device 40 via a wired or wireless connection. The configuration and function of the sensor 110 are the same as those of the vortex-induced vibration power generation system 101, and therefore a description thereof will be omitted. The power supply target 100 is assumed to be a transformer, a battery, or a power-consuming device.

[0076] The control device 113 is a microcomputer or industrial computer that functions as both a feedforward control device and a feedback control device according to a program. In other words, in the example shown in FIG. 15 , one control device functions as both a feedforward control device and a feedback control device through program control. The program that causes the control device 113 to function as a feedforward control device predefines an actuator operation amount IN that maximizes or optimizes the power generation amount Pout of the transducer 30 relative to the feedforward information FF input from the sensor 110. The program that causes the control device 113 to function as a feedback control device acquires the power generation amount Pout of the transducer 30 or a physical quantity related thereto as feedback information FB. Then, a correction amount for the actuator operation amount IN is calculated based on the feedback information FB so that the power generation amount Pout of the transducer 30 maximizes or optimizes it. The feedback information FB may include electrical physical quantities related to power generation, information on the power supply target, and health monitoring values ​​of the power generation device. The control device 113 can be manually or programmatically switched on and off. The control device 113 can also be configured as a collection of feedforward control devices and feedback control devices having separate hardware. That is, the feedforward controller and the feedback controller can be realized by different software that share hardware, or by different hardware.

[0077] 16 is a diagram showing the control flow of the vortex induced vibration power generation system 103. First, in step S301, the sensor 110 measures a physical quantity, such as the flow velocity of the fluid. Then, in step S302, the actuator operation amount of the load application device 40 is determined based on the measurement result (or prediction result) of the flow velocity, and the load applied from the interior 21 of the hollow column 20 between the upper end 22 and the lower end 23 is changed. Then, the change in load changes the structural resonance frequency of the hollow column 20, and when it matches or approaches the vortex induced vibration generation frequency, vortex induced vibration occurs, and power generation by the transducer 30 becomes possible.

[0078] In step S303, when feedback control is on, a correction amount for the actuator operation amount for adjusting the power generation amount is calculated based on the power generation amount by the transducer 30 or a physical quantity related to it. For example, PI control or PID control may be used to calculate the correction amount. Physical quantities related to the power generation amount include, for example, the axial force generated in the hollow column 20 and the vibration acceleration of the structure due to vortex-induced vibration. The axial force can be measured by an axial force sensor, and the vibration acceleration can be measured by an acceleration sensor. Note that information obtained from the axial force sensor, acceleration sensor, and fluid sensor group can also be used for environmental sensing of the vortex-induced vibration power generation device 10. Note that when the feedback control system is off, step S303 may be omitted.

[0079] The correction amount of the actuator operation amount calculated in step S303 can be used in step S302. In step S302, the correction amount calculated in step S303 is added to the actuator operation amount calculated based on the flow velocity measurement result (or prediction result). This makes it possible to maximize or optimize the amount of power generated by the transducer 30.

[0080] 2-4. Other embodiments The vortex-induced vibration power generation systems according to the first to third embodiments can also be configured as shown in Fig. 17 and Fig. 18. The vortex-induced vibration power generation system shown in Fig. 17 is configured so that a plurality of vortex-induced vibration power generation devices 10 are controlled by a common control device 114. The vortex-induced vibration power generation system shown in Fig. 18 has a plurality of modules each consisting of a hollow column 20 and a transducer 30, and one load application device 40 is combined with the plurality of modules to configure the vortex-induced vibration power generation device 10. The load application device 40 is controlled by a control device 115. The control devices 114, 115 may be feedforward control devices, feedback control devices, or a combination of a feedforward control device and a feedback control device.

[0081] 3. Verification of the relationship between load and structural resonance frequency The above equation 2 shows that the structural resonance frequency (natural frequency) of the hollow column can be controlled by manipulating the load applied to the hollow column. Here, the validity of the calculated values ​​obtained from the theoretical equation 2 is verified by comparing experimental data with analytical values ​​obtained using the finite element method.

[0082] For the verification, a weight was used, which was considered to be the wire-type load application device shown in Figure 7. The only load that can be applied with the wire-type device is a load in the compression direction. In this case, only the compression plot is considered positive.

[0083] Figure 19 is a graph showing the results of this verification. The horizontal axis of the graph represents the compressive axial force, and the vertical axis represents the natural frequency. The experimental data shown in Figure 19 was obtained using a nylon wire attached to a hollow plastic cylinder. Since the upper limit load when the device is actually used is limited to a value that provides a sufficient safety factor against the buckling load, the range of experimental data obtained was set to a compressive axial force of 0N to 40N.

[0084] As shown in the graph in Figure 19, the calculated values ​​using Equation 2 show high consistency with both the experimental data and the analytical values ​​obtained using the finite element method. This proves the validity of the analytical solution of the partial differential equation used in Equation 2.

[0085] Here, Figure 20 is a graph obtained by non-dimensionalizing each parameter in the theoretical equation of Equation 2 for a wire-type load application device. The horizontal axis of the graph represents the non-dimensional load, which is the buckling load and non-dimensionalization of the compressive axial force. The vertical axis of the graph represents the non-dimensional natural frequency, which is the natural frequency that does not consider axial force and non-dimensionalization of the natural frequency that does consider axial force. When the magnitude of the non-dimensional load is 1, the structure buckles. Although there are some variations depending on the dimensions and materials, the relationship between the non-dimensional load and the non-dimensional natural frequency for a wire-type load application device generally follows the graph shown in Figure 20.

[0086] While wire-type load applicators can only apply loads in the compressive direction, the rod-type load applicator shown in Figure 8, the double-cylinder-type load applicator shown in Figure 9, and the pressure-type load applicator shown in Figure 10 can theoretically apply loads in both the compressive and tensile directions (in the case of pressure-type load applicators, internal pressures ranging from negative to positive). Figure 21 shows graphs obtained by non-dimensionalizing the parameters of the theoretical equation (Equation 2) for rod-type, double-cylinder-type, and pressure-type load applicators. The horizontal axis of the graph represents the non-dimensional load, and the vertical axis represents the non-dimensional natural frequency. Although there are some variations depending on the dimensions and materials, the relationship between the non-dimensional load and the non-dimensional natural frequency for rod-type, double-cylinder-type, and pressure-type load applicators generally follows the graph shown in Figure 21. However, in reality, the non-dimensional load in the tensile region for rod-type and double-cylinder-type load applicators is limited by the buckling load of the internal structure.

[0087] For reference, Figures 22 to 24 show examples of the results of a finite element analysis of the relationship between the load (internal pressure in the case of a pressure type) and the natural frequency for each load application device. In the analysis results shown, for the rod type, the buckling load is low, so the effective load range is almost exclusively in the compression direction. However, if the rod diameter is large or depending on the rod material, it is expected that the effective range in the tensile direction will also expand. For the double cylinder type, the buckling load is higher than for the rod type, so it is effective to a certain extent in the tensile direction as well. For the double cylinder type, it is expected that the effective range in the tensile direction can also be expanded depending on the size and material. On the other hand, for the pressure type, the effective range is wide, from negative pressure to positive pressure.

[0088] 4. Consideration of structural materials for hollow columns When designing a vortex-induced vibration power generation system, the relationship between the Karman vortex generation frequency and the natural frequency of the structure must be considered, and the natural frequency of the structure must be designed to a certain target frequency. When considering a uniform cylindrical structure, the mass is proportional to the density. When comparing steel, aluminum, and carbon fiber reinforced composite material (CFRP), the typical densities are 7850, 2700, and 1600 kg / m, respectively. 3 Therefore, when considering structures of the same volume, CFRP is particularly advantageous due to its light weight. Furthermore, according to the formula for natural frequency, when a structure with the same cross section and natural frequency is manufactured using the three materials listed above, CFRP, in particular, has a low density and excellent specific stiffness, allowing for the creation of larger structures. This is advantageous because it increases the surface area that can be subjected to fluid. For large structures, particularly those over 10 meters in size, a lightweight structure is advantageous in terms of foundation construction, etc. Furthermore, CFRP is generally considered to have excellent fatigue strength, making it a particularly suitable material for hollow columns in this invention, which utilizes elastic vibration. While steel has low material cost and excellent fatigue strength, salt corrosion can be a problem in areas with abundant wind power, such as coastal areas, and in seawater. CFRP, being a plastic material, also has excellent corrosion resistance. [Explanation of symbols]

[0089] 10. Vortex-induced vibration power generation device 20 hollow pillar 20A hollow column (rectangular cross section) 20B Hollow column (H-shaped cross section) 21 Inside 22 Upper end (free end) 23 Lower end (fixed end) 25 Large diameter section 30 transducers 40 Load application device 50 base 100 Power Supply Target 101 Vortex-induced vibration power generation system 102 Vortex-induced vibration power generation system 103 Vortex-induced vibration power generation system 110 Sensors 111 Control device (feedforward control device) 112 Control device (feedback control device) 113 Control device (feedforward and feedback controller) 410 Load application device 411 Wire (linear components) 412 Winding machine (actuator) 420 Load application device 421 Rod (rod member) 422 Worm gear (actuator) 430 Load application device 431 Internal hollow column (second hollow column) 432 Cylinder (actuator) 440 Fluid Pump (Load Applicator) 441 Suction / discharge port

Claims

1. a hollow post having a free end and a fixed end; a transducer for converting the vibration energy of the hollow column into electrical energy; a load application device that applies a load between the free end and the fixed end from inside the hollow column. A vortex-induced vibration power generation device characterized by:

2. 2. The vortex-induced vibration power generation system according to claim 1, The load application device is a linear member provided inside the hollow column and connecting the free end and the fixed end; an actuator that pulls the linear member A vortex-induced vibration power generation device characterized by:

3. 2. The vortex-induced vibration power generation system according to claim 1, The load application device is a rod member provided inside the hollow column, one end of which is fixed to the free end and the other end of which is fixed to the fixed end; an actuator for pushing and pulling or extending and contracting the rod member A vortex-induced vibration power generation device characterized by:

4. 2. The vortex-induced vibration power generation system according to claim 1, The load application device is an inner hollow column provided inside the hollow column, one end of which is fixed to the free end and the other end of which is fixed to the fixed end; and an actuator for pushing, pulling, or expanding the internal hollow column. A vortex-induced vibration power generation device characterized by:

5. 2. The vortex-induced vibration power generation system according to claim 1, The load application device includes an actuator that increases or decreases the pressure inside the hollow column. A vortex-induced vibration power generation device characterized by:

6. The vortex-induced vibration power generation device according to any one of claims 1 to 5, a feedforward control device that acquires a measured value or a predicted value of a physical quantity of a fluid flowing around the hollow column and controls the load application device so as to change the load in accordance with the measured value or the predicted value. A vortex-induced vibration power generation system.

7. The vortex-induced vibration power generation device according to any one of claims 1 to 5, a feedback control device that controls the load application device so as to change the load in accordance with the physical quantity of the electric power generated by the transducer. A vortex-induced vibration power generation system.

8. The vortex-induced vibration power generation device according to any one of claims 1 to 5, a feedforward control device that acquires a measured value or a predicted value of a physical quantity of a fluid flowing around the hollow column and controls the load application device so as to change the load in accordance with the measured value or the predicted value; a feedback control device that controls the load application device so as to change the load in accordance with the physical quantity of the electric power generated by the transducer. A vortex-induced vibration power generation system.

Images