Fluid kinetic energy capture device based on vortex cylinder and flexible wake slapping plate

Abstract

The application discloses a fluid kinetic energy capturing device based on a vortex cylinder and a flexible wake slapping plate, wherein the vortex cylinder energy collection system is used for generating vortex-induced vibration response under the action of fluid to collect fluid kinetic energy; the flexible wake slapping energy collection system is arranged at the rear of the vortex cylinder energy collection system in the flow direction; when the vortex cylinder energy collection system cannot be excited out of the resonance lock-in frequency area, the flexible wake slapping energy collection system is used for capturing fluid kinetic energy under the action of the unsteady flow vortex environment shed at the rear of the vortex cylinder energy collection system; when the vortex cylinder energy collection system generates vortex-induced vibration response under the action of fluid, the flexible wake slapping energy collection system is used for assisting in capturing fluid kinetic energy. The energy collection mode of the application is suitable for a wide range of working flow rates, not only improves the working ability out of the resonance lock-in frequency area, but also improves the fluid energy conversion rate in a composite manner, has strong energy collection robustness, high energy conversion rate, is green and environment-friendly, and is suitable for underwater environment.

Description

Technical Field

[0001] This invention relates to the technical field of renewable fluid kinetic energy capture and conversion, specifically to a fluid kinetic energy capture device based on a vortex-vibrating cylinder and a flexible wake-beating plate. Background Technology

[0002] Structures in contact with fluids (water, wind, sediment, etc.) are often inevitably subjected to flow-induced forces, resulting in structural deformation or vibration, forming phenomena such as vortex-induced vibration. Vortex-induced vibration is generally considered high-energy and harmful; however, recent studies have also shown that during the vibration process, structures can often absorb a considerable amount of fluid kinetic energy. Therefore, vortex-induced vibration also has great potential for fluid energy capture.

[0003] The ever-increasing energy demand of human society and the depletion of environmental resources have created a sharp contradiction, making the search for and research into renewable energy harvesting methods an urgent priority. The ocean, covering more than 70% of the Earth's surface, possesses abundant energy reserves; statistics show that global ocean current energy reserves alone reach 76.6 billion kW. Currently, tidal energy converters using turbines as conversion devices, nearshore oscillating water columns and offshore oscillating harvesting bodies using wave energy, and offshore floating wind turbines combining wind and wave energy have seen significant development. Compared to these technologies, clean energy harvesting devices based on vortex-induced vibration have significant advantages. For example, energy conversion methods such as turbines require high start-up speeds and cannot harvest low-grade energy in low-velocity waters, while vortex-induced vibration energy harvesting devices can achieve frequency-locked resonance at low speeds to complete energy collection. These vortex-induced vibration energy harvesting devices mainly consist of elastically supported oscillators, mechanical transmission devices, and power generation equipment systems. The working principle is as follows: when the incoming fluid flows laterally around the blunt body oscillator, it will cause the oscillator to generate a vortex-induced vibration response perpendicular to the direction of the incoming flow. During this process, the transmission device converts the linear motion of the vibration into rotational motion, which in turn drives the generator to rotate and generate electrical energy.

[0004] Many technologies have been developed for vortex-induced vibration energy harvesting devices, but the following key challenges remain: (1) The frequency-locked resonance range of vortex-induced vibration is limited. Within the frequency-locked resonance range, the oscillator can oscillate significantly to harvest energy through fluid-structure interaction. However, outside the frequency-locked resonance range, the oscillator cannot effectively harvest energy, which means that the working range of such devices is limited and the energy harvesting robustness is poor; (2) Although vortex-induced vibration has unique advantages in energy harvesting, its energy conversion efficiency is limited and there is room for further improvement. Summary of the Invention

[0005] This invention aims to at least solve one of the technical problems existing in the prior art. Therefore, one objective of this invention is to propose a fluid kinetic energy harvesting device based on a vortex-vibrating cylinder and a flexible wake-beating plate. This energy harvesting method is adaptable to a wide range of working flow velocities, exhibits strong energy harvesting robustness, high energy conversion efficiency, and is environmentally friendly, making it suitable for underwater environments.

[0006] A fluid kinetic energy harvesting device based on a vortex-vibrating cylinder and a flexible wake-beating plate according to an embodiment of the present invention includes:

[0007] support;

[0008] A vortex-induced cylindrical energy collection system is mounted on the support; the vortex-induced cylindrical energy collection system is used to generate vortex-induced vibration response under the action of fluid and collect fluid kinetic energy.

[0009] A flexible wake-blowing energy collection system is mounted on the support and spaced apart behind the vortex-induced cylindrical energy collection system in the incoming flow direction. When the vortex-induced cylindrical energy collection system is outside the resonant frequency-locked region and cannot start oscillation, the flexible wake-blowing energy collection system is used to capture the fluid kinetic energy under the influence of the unsteady flow vortex environment that falls off behind the vortex-induced cylindrical energy collection system. When the vortex-induced cylindrical energy collection system generates vortex-induced vibration response under the action of fluid, the flexible wake-blowing energy collection system is used to assist in capturing fluid kinetic energy.

[0010] The fluid kinetic energy harvesting device based on a vortex-vibrating cylinder and a flexible wake-beating plate according to an embodiment of the present invention operates on the following principle:

[0011] Under the influence of the incoming water flow velocity U, when the fluid flows past the oscillator of the vortex-driven cylindrical energy collection system, the fluid in contact with the oscillator surface is slowed down due to viscosity, thus forming a boundary layer. Furthermore, the boundary layer separates, causing periodic vortices to detach from the rear of the oscillator, forming a vortex street, which in turn alters the pressure distribution along the oscillator's surface. Different pressure differences generate periodically alternating lateral lift, causing the oscillator to vibrate periodically, forming vortex-induced vibration. As the incoming water flow velocity U changes, the vortex shedding frequency in the wake behind the oscillator changes accordingly. Specifically, when the vortex shedding frequency matches the natural frequency of the vortex-driven cylindrical energy collection system, the oscillator will oscillate significantly, forming a frequency-locked resonance phenomenon, thereby continuously converting fluid kinetic energy into mechanical energy and then into electrical energy through the vortex-driven cylindrical energy collection system. The flexible wake-pulsating energy collection system can generate an excitation response in the vortex-vibrating cylindrical energy collection system, and can even work simultaneously in the frequency-locked resonance region to assist in capturing fluid kinetic energy, thereby improving the overall energy conversion efficiency of the equipment.

[0012] When the vortex shedding frequency generated by the incoming water flow velocity U bypassing the oscillator of the vortex-vibrating cylindrical energy collection system differs significantly from the natural frequency of the system, the oscillator cannot achieve frequency-locked resonance, resulting in a small vibration amplitude. In this case, the energy harvesting effect of the vortex-vibrating cylindrical energy collection system is poor. However, in the non-frequency-locked resonance region, the vortex intensity of the wake from the oscillator of the vortex-vibrating cylindrical energy collection system is higher and more concentrated, which is beneficial for the flexible wake-pulling energy collection system to operate and harvest energy. On one hand, the vortex wake of the oscillator of the vortex-vibrating cylindrical energy collection system contains alternating unsteady vortices, which is conducive to exciting the flexible wake-pulling energy collection system to produce pulsating behavior; on the other hand, even under uniform incoming flow velocity, the flexible wake-pulling energy collection system can self-excite and generate pulsating behavior. Therefore, the flexible wake-pulling energy collection system can continuously capture fluid kinetic energy by generating large-amplitude pulsating phenomena in the vortex wake of the aforementioned vortex-vibrating cylindrical energy collection system, thereby improving the overall energy conversion efficiency of the equipment.

[0013] The fluid kinetic energy capture device based on a vortex-vibrating cylinder and a flexible wake flapping plate according to an embodiment of the present invention has the following advantages: (1) The energy collection method is adaptable to a wide range of working flow velocities and has strong energy collection robustness. When the water flow velocity is in the vortex-vibrating frequency-locked resonance zone, both the upstream vortex-vibrating cylinder energy collection system and the downstream flexible wake flapping energy collection system can convert fluid kinetic energy; when the flow velocity is outside the range of vortex-vibrating frequency-locked resonance conditions, the upstream vortex-vibrating cylinder energy collection system cannot effectively collect energy, but the downstream flexible wake flapping energy collection system can swing significantly in the Karman vortex street that falls off behind the oscillator of the upstream vortex-vibrating cylinder energy collection system, thereby effectively capturing energy and making up for the existing defects of vortex-vibrating energy capture. (2) High energy conversion rate. Combining the vortex-induced frequency-locked resonance of the upstream vortex-vibrating cylinder energy collection system and the flexible flapping of the downstream flexible wake flapping energy collection system under the action of unsteady wake vortex, the fluid kinetic energy capture efficiency can be significantly improved. (3) Green and environmentally friendly. On the one hand, this device can effectively capture renewable fluid kinetic energy; on the other hand, compared with rotating energy harvesting mechanisms such as blades and turbines, it is more environmentally friendly to marine organisms. In summary, the fluid kinetic energy harvesting device based on a vortex-vibrating cylinder and a flexible wake-beating plate in this invention has a wide range of working flow velocities. It not only improves the working capability outside the resonant frequency-locking region, but also comprehensively improves the fluid energy conversion rate. It has strong energy harvesting robustness, high energy conversion efficiency, is green and environmentally friendly, and is suitable for underwater environments.

[0014] In some embodiments, the flexible wake flapping energy collection system includes a flexible flapping plate, a piezoelectric structure, and a flapping plate piezoelectric energy collection device. The leading edge of the flexible flapping plate extends vertically and is connected to the support. The trailing edge of the flexible flapping plate is a free end. The flexible flapping plate can perform multiple free flapping and bending movements. The piezoelectric structure is disposed on the flexible flapping plate, and the flapping plate piezoelectric energy collection device is connected to the piezoelectric structure.

[0015] In some embodiments, the flexible wake flapping energy collection system further includes a shaft connected to the leading edge of the flexible flapping plate, and the shaft is rotatably supported on the bracket.

[0016] In some embodiments, the shaft is connected to the bracket via a rotating element.

[0017] In some embodiments, there are two rotating members, which are respectively connected to the upper and lower ends of the shaft, and are also connected to the bracket.

[0018] In some embodiments, the piezoelectric structure includes a piezoelectric layer fixed to the flexible tapping plate.

[0019] In some embodiments, the piezoelectric structure further includes a substrate layer, which is attached to the flexible tapping plate, and the piezoelectric layer is attached to the substrate layer.

[0020] In some embodiments, the vortex-induced cylindrical energy collection system includes a vortex-induced cylindrical vibrator, a transmission mechanism, and a vibration energy collection device; the vortex-induced cylindrical vibrator is vertically arranged in front of the flexible tapping plate and connected to the support through the transmission mechanism, and the vibration energy collection device is connected to the transmission mechanism.

[0021] In some embodiments, the transmission mechanism includes an upper sliding member, a lower sliding member, an upper spring, a lower spring, a rack, and a gear; the upper sliding member and the lower sliding member are respectively fixed to the upper and lower ends of the vortex-induced cylindrical oscillator, and the upper and lower sliding members are respectively slidably arranged laterally on the support; the upper spring and the lower spring are arranged laterally on one side of the upper and lower sliding members, and one end of the upper spring and the lower spring is fixed to the support, while the other end of the upper spring and the lower spring is respectively connected to the upper and lower sliding members; the rack is arranged laterally on the other side of the lower sliding member and is slidably arranged laterally on the support, and one end of the rack is fixed to the lower sliding member; the gear meshes with the rack, and the gear is connected to the vibration energy collection device through a gear shaft.

[0022] In some embodiments, based on simulation experimental verification results, the damping coefficient of the vortex-induced cylindrical energy collection system is selected as 0.1 to 0.2, the ratio of the structural mass of the vortex-induced cylindrical oscillator to its own displacement mass is 2 to 5:1, the distance between the vortex-induced cylindrical oscillator and the flexible flapping plate is G, G = 6D, where D represents the diameter of the vortex-induced cylindrical oscillator, the length from the leading edge to the trailing edge of the flexible flapping plate is 3D, and the dimensionless stiffness of the flexible wake flapping energy collection system is 0.4 to 0.6.

[0023] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0024] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0025] Figure 1 This is a schematic diagram of the fluid kinetic energy capture device based on a vortex-vibrating cylinder and a flexible wake flapping plate according to the present invention.

[0026] Figure 2a and Figure 2b This is a schematic diagram illustrating the working principle of the fluid kinetic energy capture device based on a vortex-vibrating cylinder and a flexible wake-beating plate of the present invention.

[0027] Figure label:

[0028] Support 1; Front upper support 101; Front lower support 102; Front vertical support 103; Rear upper support 104; Rear lower support 105; Rear vertical support 106; Front and rear connecting frame 107; Vortex-induced cylindrical energy collection system 2; Vortex-induced cylindrical vibrator 201; Transmission mechanism 202; Upper sliding member 2021; Lower sliding member 2022; Upper spring 2023; Lower spring 2024; Rack 2025; Gear 2026; Vibration energy collection device 203; Flexible wake flapping energy collection system 3; Flexible flapping plate 301; Piezoelectric structure 302; Piezoelectric layer 3021; ​​Substrate layer 3022; Piezoelectric energy collection device for flapping plate 303; Shaft 304; Rotating member 305; Rotating mechanism 3051; Piezoshaft connector 3052. Detailed Implementation

[0029] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0030] The following is combined with Figures 1 to 2bThis invention describes a fluid kinetic energy capture device based on a vortex-vibrating cylinder and a flexible wake-beating plate, according to an embodiment of the present invention.

[0031] like Figures 1 to 2b As shown, the fluid kinetic energy harvesting device based on a vortex-vibrating cylinder and a flexible wake-beating plate according to an embodiment of the present invention includes a support 1, a vortex-vibrating cylinder energy collection system 2, and a flexible wake-beating energy collection system 3.

[0032] Among them, the bracket 1 mainly serves to reliably support the vortex-vibration cylindrical energy collection system 2 and the flexible wake-pulsating energy collection system 3.

[0033] The vortex-induced cylindrical energy collection system 2 is mounted on the support 1; the vortex-induced cylindrical energy collection system 2 is used to generate vortex-induced vibration response under the action of fluid and collect fluid kinetic energy.

[0034] The flexible wake flapping energy collection system 3 is mounted on the support 1 and is arranged at intervals behind the vortex-induced cylindrical energy collection system 2 in the direction of incoming flow. When the vortex-induced cylindrical energy collection system 2 is outside the resonant frequency-locked region and cannot start oscillation, the flexible wake flapping energy collection system 3 is used to capture the fluid kinetic energy under the action of the unsteady flow vortex environment that falls off behind the vortex-induced cylindrical energy collection system 2. When the vortex-induced cylindrical energy collection system 2 generates vortex-induced vibration response under the action of fluid, the flexible wake flapping energy collection system 3 is used to assist in capturing fluid kinetic energy.

[0035] The fluid kinetic energy harvesting device based on a vortex-vibrating cylinder and a flexible wake-beating plate according to an embodiment of the present invention operates on the following principle:

[0036] refer to Figure 2a Under the influence of the incoming water flow velocity U, when the fluid flows past the oscillator of the vortex-induced cylindrical energy collection system 2 (refer to the vortex-induced cylindrical oscillator 201 below), the fluid in contact with the oscillator surface is decelerated due to viscosity, thus forming a boundary layer. Furthermore, the boundary layer separates, causing periodic vortices to detach from the rear of the oscillator, forming a vortex street, which in turn alters the pressure distribution along the oscillator's structural surface. Different pressure differences generate periodically alternating lateral lift, causing the oscillator to vibrate periodically, forming vortex-induced vibration. As the incoming water flow velocity U changes, the vortex shedding frequency in the wake behind the oscillator changes accordingly. Specifically, when the vortex shedding frequency matches the natural frequency of the vortex-induced cylindrical energy collection system 2, the oscillator will oscillate significantly, forming a frequency-locked resonance phenomenon, thereby continuously converting fluid kinetic energy into mechanical energy and then into electrical energy through the vortex-induced cylindrical energy collection system 2. The flexible wake-pulsating energy collection system 3 generates an excitation response in the vortex-vibration cylindrical energy collection system 2, and can even work simultaneously in the frequency-locked resonance region to assist in capturing fluid kinetic energy, thereby improving the overall energy conversion efficiency of the equipment.

[0037] refer to Figure 2bWhen the vortex shedding frequency generated by the incoming water flow velocity U bypassing the oscillator of the vortex-vibrating cylindrical energy collection system 2 differs significantly from the natural frequency of the system, the oscillator cannot achieve frequency-locked resonance, resulting in a small vibration amplitude. In this case, the energy harvesting effect of the vortex-vibrating cylindrical energy collection system 2 is poor. However, in the non-frequency-locked resonance region, the vortex intensity released by the wake of the oscillator of the vortex-vibrating cylindrical energy collection system 2 is higher and more concentrated, which is beneficial for the flexible wake-pulling energy collection system 3 to operate and harvest energy. On the one hand, the vortex wake of the oscillator of the vortex-vibrating cylindrical energy collection system 2 contains alternating unsteady vortices, which is conducive to exciting the flexible wake-pulling energy collection system 3 to produce pulsating behavior; on the other hand, even under uniform incoming flow velocity, the flexible wake-pulling energy collection system 3 can self-excite and generate pulsating behavior. Therefore, the flexible wake-pulling energy collection system 3 can continuously capture fluid kinetic energy by generating large-amplitude pulsating phenomena in the vortex wake of the upper vortex-vibrating cylindrical energy collection system 2, thereby improving the overall energy conversion efficiency of the equipment.

[0038] The fluid kinetic energy capture device based on the vortex-vibrating cylinder and the flexible wake flapping plate according to the embodiments of the present invention has the following advantages: (1) The energy collection method is adaptable to a wide range of working flow velocities and has strong energy collection robustness. When the water flow velocity is in the vortex-vibrating frequency-locked resonance zone, both the upstream vortex-vibrating cylinder energy collection system 2 and the downstream flexible wake flapping energy collection system 3 can convert fluid kinetic energy; when the flow velocity is outside the range of vortex-vibrating frequency-locked resonance conditions, the upstream vortex-vibrating cylinder energy collection system 2 cannot effectively collect energy, but the downstream flexible wake flapping energy collection system 3 can swing significantly in the Karman vortex street that falls off behind the oscillator of the upstream vortex-vibrating cylinder energy collection system 2, thereby effectively capturing energy and making up for the existing defects of vortex-vibrating energy capture. (2) High energy conversion rate. Combining the vortex-induced frequency-locked resonance of the upstream vortex-vibrating cylinder energy collection system 2 and the flexible flapping of the downstream flexible wake flapping energy collection system 3 under the action of unsteady wake vortex, the fluid kinetic energy capture efficiency can be significantly improved. (3) Green and environmentally friendly. On the one hand, this device can effectively capture renewable fluid kinetic energy; on the other hand, compared with rotating energy harvesting mechanisms such as blades and turbines, it is more environmentally friendly to marine organisms. In summary, the fluid kinetic energy harvesting device based on a vortex-vibrating cylinder and a flexible wake-beating plate in this invention has a wide range of working flow velocities. It not only improves the working capability outside the resonant frequency-locking region, but also comprehensively improves the fluid energy conversion rate. It has strong energy harvesting robustness, high energy conversion efficiency, is green and environmentally friendly, and is suitable for underwater environments.

[0039] In some embodiments, the flexible wake flapping energy collection system 3 includes a flexible flapping plate 301, a piezoelectric structure 302, and a flapping plate piezoelectric energy collection device 303. The leading edge of the flexible flapping plate 301 extends vertically and is connected to the support 1. The trailing edge of the flexible flapping plate 301 is a free end. The flexible flapping plate 301 can perform multiple free flapping and bending movements. The piezoelectric structure 302 is disposed on the flexible flapping plate 301, and the flapping plate piezoelectric energy collection device 303 is connected to the piezoelectric structure 302.

[0040] refer to Figure 2b When the vortex-induced cylindrical energy collection system 2 cannot form a frequency-locked resonance phenomenon, its energy harvesting effect is poor. However, in the non-frequency-locked resonance region, the vortex intensity of the wake of the vortex-induced cylindrical energy collection system 2 is higher and more concentrated, which is beneficial for the operation and energy harvesting of the flexible wake-pulling energy collection system 3 of the present invention. On the one hand, the wake of the vortex-induced cylindrical energy collection system 2 has alternating unsteady vortices, which is beneficial for exciting the flexible pulsating plate 301 to produce pulsating behavior; on the other hand, even under a uniform incoming flow velocity, the flexible pulsating plate 301 can self-excite and produce pulsating behavior. Therefore, the flexible pulsating plate 301 can produce a large-scale pulsating phenomenon in the wake of the vortex-induced cylindrical energy collection system 2 upstream. Furthermore, under the above mechanism, the flexible pulsating plate 301 will drive the piezoelectric structure 302 to deform and generate strain. Correspondingly, this strain energy is converted into piezoelectric voltage and corresponding power on the piezoelectric load resistor and transmitted to the pulsating plate piezoelectric energy collection device 303. Because the flexible flapping plate 301 itself has a restoring force, the flexible wake flapping energy collection system 3 can perform reciprocating periodic flapping in the flow environment and continuously capture fluid kinetic energy.

[0041] refer to Figure 2a and Figure 2b As the inflow velocity U changes, when the efficiency of the upstream vortex-vibrating cylindrical energy collection system 2 is limited, the downstream flexible wake-beating energy collection system 3 has favorable operating conditions. It should be noted that in this embodiment, the upstream vortex-vibrating cylindrical energy collection system 2 and the downstream flexible wake-beating energy collection system can also operate simultaneously under relatively favorable conditions, improving the overall efficiency and operational capability of the energy collection system.

[0042] In some embodiments, the flexible wake flapping energy collection system 3 further includes a shaft 304, which is connected to the leading edge of the flexible flapping plate 301. For example, the connection can be made by the leading edge of the flexible flapping plate 301 being nested on the shaft 304. The shaft 304 is rotatably supported on the bracket 1. In this way, the leading edge of the flexible flapping plate 301 can perform single-degree-of-freedom rotational motion, and combined with the fact that the rest of the flexible flapping plate 301 can perform multi-degree-of-freedom flapping, bending, and other movements, it is more conducive to the flexible flapping plate 301 flapping in different fluid flow velocities and effectively capturing fluid kinetic energy.

[0043] In some embodiments, the shaft 304 is connected to the bracket 1 via the rotating member 305, which enables the leading edge of the flexible flapping plate 301 to perform a single degree of freedom rotational motion, and the connection is convenient and reliable.

[0044] The rotating component 305 includes a rotating mechanism 3051 and a flapping shaft connector 3052 connected to each other. The shaft 304 is connected to the rotating mechanism 3051, and the flapping shaft connector 3052 is connected to the bracket 1.

[0045] In some embodiments, there are two rotating members 305, which are respectively connected to the upper end and the lower end of the shaft 304, and the two rotating members 305 are connected to the bracket 1, making the connection convenient and reliable.

[0046] In some embodiments, the piezoelectric structure 302 includes a piezoelectric layer 3021, which is fixed to the flexible tapping plate 301. Thus, the flexible tapping plate 301 causes the piezoelectric layer 3021 to deform and generate strain. Correspondingly, this strain energy is converted into piezoelectric voltage and corresponding power on the piezoelectric load resistor and transmitted to the tapping plate piezoelectric energy collection device 303.

[0047] In some embodiments, the piezoelectric structure 302 further includes a substrate layer 3022, which is attached to the flexible flapping plate 301, and a piezoelectric layer 3021 is attached to the substrate layer 3022. When the flexible flapping plate 301 flaps in the fluid, it causes the substrate layer 3022 to displace. When the displacement occurs, the piezoelectric layer 3021 attached to the substrate layer 3022 also deforms and generates strain. Correspondingly, this strain energy is converted into piezoelectric voltage and corresponding power on the piezoelectric load resistor and transmitted to the flapping plate piezoelectric energy collection device 303.

[0048] In some embodiments, the vortex-induced cylindrical energy collection system 2 includes a vortex-induced cylindrical vibrator 201, a transmission mechanism 202, and a vibration energy collection device 203; the vortex-induced cylindrical vibrator 201 is vertically arranged in front of the flexible flapping plate 301 and connected to the support 1 through the transmission mechanism 202, and the vibration energy collection device 203 is connected to the transmission mechanism 202.

[0049] It is understandable that the vortex-induced vibration cylindrical oscillator 201 has a cylindrical shape. During operation, refer to... Figure 2aUnder the influence of the incoming water flow velocity U, when the fluid flows past the vortex-induced vibration cylindrical oscillator 201, the fluid in contact with the surface of the vortex-induced vibration cylindrical oscillator 201 is decelerated due to viscosity, thus forming a boundary layer. Furthermore, the boundary layer separates, causing periodic vortices to detach from the rear of the vortex-induced vibration cylindrical oscillator 201, forming a vortex street, which in turn alters the pressure distribution along the structural surface. Different pressure differences generate periodically alternating lateral lift, causing the vortex-induced vibration cylindrical oscillator 201 to vibrate periodically, forming vortex-induced vibration. As the incoming water flow velocity U changes, the vortex shedding frequency of the wake behind the vortex-induced vibration cylindrical oscillator 201 changes accordingly. Specifically, when the vortex shedding frequency matches the structural natural frequency of the vortex-induced vibration cylindrical energy collection system 2, the vortex-induced vibration cylindrical oscillator 201 will oscillate significantly, forming a frequency-locked resonance phenomenon. Under these conditions, the kinetic energy of the vortex-induced cylindrical oscillator 201 is transmitted to the cylindrical oscillator energy collection device through the transmission mechanism 202, and the cylindrical oscillator energy collection device works to convert energy.

[0050] refer to Figure 2b When the vortex shedding frequency generated by the water flow velocity U bypassing the vortex-induced cylindrical oscillator 201 differs significantly from the natural frequency of the vortex-induced cylindrical energy collection system 2, the vortex-induced cylindrical oscillator 201 cannot form a frequency-locked resonance phenomenon, and therefore its vibration amplitude is small. In this case, the energy harvesting effect of the vortex-induced cylindrical energy collection system 2 is poor. However, the vortex wake of the vortex-induced cylindrical oscillator 201 contains alternating unsteady vortices, which is beneficial for exciting the flexible flapping plate 301 to produce flapping behavior.

[0051] In some embodiments, the transmission mechanism 202 includes an upper sliding member 2021, a lower sliding member 2022, an upper spring 2023, a lower spring 2024, a rack 2025, and a gear 2026; the upper sliding member 2021 and the lower sliding member 2022 are respectively fixed to the upper and lower ends of the vortex-induced cylindrical oscillator 201, and the upper sliding member 2021 and the lower sliding member 2022 are respectively slidably arranged laterally on the bracket 1; the upper spring 2023 and the lower spring 2024 are arranged laterally on the upper sliding member 2021 and the lower sliding member 2022. On one side, one end of the upper spring 2023 and the lower spring 2024 are fixed to the bracket 1, and the other ends of the upper spring 2023 and the lower spring 2024 are respectively connected to the upper sliding member 2021 and the lower sliding member 2022; the rack 2025 is arranged in the transverse direction on the other side of the lower sliding member 2022 and can be slidably arranged in the transverse direction on the bracket 1, and one end of the rack 2025 is fixed to the lower sliding member 2022; the gear 2026 meshes with the rack 2025, and the gear 2026 is connected to the vibration energy collection device 203 through the circumference of the gear 2026.

[0052] refer to Figure 2aUnder the influence of the incoming water flow velocity U, when the fluid flows past the vortex-induced vibration cylindrical oscillator 201, the fluid in contact with the surface of the vortex-induced vibration cylindrical oscillator 201 is decelerated due to viscosity, thus forming a boundary layer. Furthermore, the boundary layer separates, causing periodic vortices to detach from the rear of the vortex-induced vibration cylindrical oscillator 201, forming a vortex street, which in turn alters the pressure distribution along the structural surface. Different pressure differences generate periodically alternating lateral lift, causing the vortex-induced vibration cylindrical oscillator 201 to vibrate periodically, forming vortex-induced vibration. As the incoming water flow velocity U changes, the vortex shedding frequency of the wake behind the vortex-induced vibration cylindrical oscillator 201 changes accordingly. Specifically, when the vortex shedding frequency matches the structural natural frequency of the vortex-induced vibration cylindrical energy collection system 2, the vortex-induced vibration cylindrical oscillator 201 will oscillate significantly, forming a frequency-locked resonance phenomenon. Under these conditions, the vortex-induced cylindrical oscillator 201, together with the upper sliding member 2021 and the lower sliding member 2022, undergoes oscillating displacement on the support 1. Furthermore, the rack 2025, fixed to the lower sliding member 2022, is also pushed by the vortex-induced vibration of the cylindrical oscillator 201 to generate lateral linear motion, and then uses meshing transmission to cause the gear 2026 to rotate, driving the cylindrical oscillator energy collection device to work and convert energy. Furthermore, during the vortex-induced vibration motion, the vortex-induced cylindrical oscillator 201 will compress or stretch the upper spring 2023 and the lower spring 2024, and is subjected to the restoring force of the upper spring 2023 and the lower spring 2024 to maintain periodic reciprocating motion, continuously converting fluid kinetic energy into mechanical energy and then into electrical energy.

[0053] In some embodiments, based on simulation results, the damping coefficient of the vortex-induced cylindrical energy collection system 2 is selected as 0.1–0.2; the ratio of the structural mass to the self-displaced mass of the vortex-induced cylindrical oscillator 201 is 2–5:1; the distance between the vortex-induced cylindrical oscillator 201 and the flexible flapping plate 301 is G, where G = 6D, and D represents the diameter of the vortex-induced cylindrical oscillator 201; the length from the leading edge to the trailing edge of the flexible flapping plate 301 is 3D; and the dimensionless stiffness of the flexible wake flapping energy collection system 3 is 0.4–0.6 (defined as the ratio of dimensional stiffness to density, the square of the incoming flow velocity U, and the square of the flapping plate length). By selecting the values ​​of the above key parameters, the frequency-locked resonance speed range and the motor energy conversion efficiency can be better controlled.

[0054] In some embodiments, the bracket 1 includes a front upper bracket 101, a front lower bracket 102, a front vertical bracket 103, a rear upper bracket 104, a rear lower bracket 105, a rear vertical bracket 106, and a front and rear connecting frame 107; the front upper bracket 101, the front lower bracket 102, the rear upper bracket 104, and the rear lower bracket 105 all extend laterally, the front vertical bracket 103 is connected between the front upper bracket 101 and the front lower bracket 102, the rear vertical bracket 106 is connected between the rear upper bracket 104 and the rear lower bracket 105, and the front and rear connecting frame 107 is connected between the front lower bracket 102 and the rear lower bracket 105.

[0055] The upper and lower ends of the vortex-induced cylindrical oscillator 201 are respectively connected to the upper sliding member 2021 and the lower sliding member 2022, which are slidably mounted on the upper front support 101 and the lower front support 102. The upper spring 2023 and the lower spring 2024 are arranged laterally on one side of the upper sliding member 2021 and the lower sliding member 2022, and one end of the upper spring 2023 and the lower spring 2024 are respectively fixed to one end of the front upper bracket 101 and the front lower bracket 102, and the other end of the upper spring 2023 and the lower spring 2024 are respectively connected to the upper sliding member 2021 and the lower sliding member 2022; the rack 2025 is arranged laterally on the other side of the lower sliding member 2022 and can be slidably arranged laterally on the front lower bracket 102, and one end of the rack 2025 is fixed to the lower sliding member 2022; the gear 2026 meshes with the rack 2025, and the gear 2026 is connected to the vibration energy collection device 203 through the gear shaft.

[0056] The front edge of the flexible flapping plate 301 is nested on the shaft 304. The upper and lower ends of the shaft 304 are connected to the upper rear bracket 104 and the lower rear bracket 105 respectively through two rotating parts 305.

[0057] In summary, this embodiment of the invention uses an elastically supported vortex-induced vibration cylindrical oscillator 201 as the front-end energy conversion oscillator and a flexible flapping plate 301 as the rear-end energy conversion oscillator, combining an energy transfer mechanism and a conversion mechanism to form a power generation device. Considering the abundant energy and favorable non-uniform flow distribution of the unsteady vortex detached behind the vortex-induced vibration cylindrical oscillator 201, the rear-end flexible flapping plate 301, combined with a piezoelectric structure 302, captures the fluid kinetic energy in the upstream vortex-induced vibration wake. Under this setting, when the vortex-induced vibration cylindrical oscillator 201 is outside the resonant frequency-locking region and cannot start oscillating, the flexible flapping plate 301 can exhibit a large-amplitude flapping phenomenon in the upstream vortex street to compensate for insufficient energy capture under this working condition and improve the overall energy capture robustness. Furthermore, within the frequency-locking resonance region, the flexible flapping plate 301 can also act simultaneously, further enhancing the overall energy conversion efficiency of the device. This embodiment of the invention has a simple, reliable, and environmentally friendly overall mechanism, suitable for underwater environments, and eliminates high-speed rotating mechanisms such as turbines and blades, making it environmentally friendly to the marine environment.

[0058] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0059] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A fluid kinetic energy harvesting device based on a vortex-vibrating cylinder and a flexible wake-beating plate, characterized in that, include: support; A vortex-vibrating cylindrical energy collection system, wherein the vortex-vibrating cylindrical energy collection system is mounted on the support; The vortex-induced cylindrical energy collection system is used to generate vortex-induced vibration response under the action of fluid and collect fluid kinetic energy; A flexible wake-blowing energy collection system is mounted on the support and spaced apart behind the vortex-induced cylindrical energy collection system in the incoming flow direction. When the vortex-induced cylindrical energy collection system is outside the resonant frequency-locked region and cannot start oscillation, the flexible wake-blowing energy collection system is used to capture the fluid kinetic energy under the influence of unsteady flow vortices falling behind the vortex-induced cylindrical energy collection system. When the vortex-induced cylindrical energy collection system generates vortex-induced vibration response under the influence of fluid, the flexible wake-blowing energy collection system is used to assist in capturing fluid kinetic energy. The flexible wake flapping energy collection system includes a flexible flapping plate, a piezoelectric structure, and a flapping plate piezoelectric energy collection device. The leading edge of the flexible flapping plate extends vertically and is connected to the support. The trailing edge of the flexible flapping plate is a free end. The flexible flapping plate can perform multiple free flapping and bending movements. The piezoelectric structure is disposed on the flexible flapping plate, and the flapping plate piezoelectric energy collection device is connected to the piezoelectric structure. The vortex-induced cylindrical energy collection system includes a vortex-induced cylindrical vibrator, a transmission mechanism, and a vibration energy collection device; the vortex-induced cylindrical vibrator is vertically arranged in front of the flexible tapping plate and connected to the support through the transmission mechanism, and the vibration energy collection device is connected to the transmission mechanism. in, The transmission mechanism includes an upper sliding member, a lower sliding member, an upper spring, a lower spring, a rack, and a gear. The upper and lower sliding members are respectively fixed to the upper and lower ends of the vortex-induced cylindrical oscillator, and are respectively slidably mounted on the support. The upper and lower springs are arranged laterally on one side of the upper and lower sliding members, with one end of each spring fixed to the support and the other end connected to the upper and lower sliding members, respectively. The rack is arranged laterally on the other side of the lower sliding member and is slidably mounted on the support, with one end of the rack fixed to the lower sliding member. The gear meshes with the rack and is connected to the vibration energy collection device via a gear shaft. Based on the simulation results, the damping coefficient of the vortex-induced cylindrical energy collection system is selected to be 0.1~0.2, the mass ratio of the vortex-induced cylindrical oscillator structure to its own displacement mass is 2~5:1, the distance between the vortex-induced cylindrical oscillator and the flexible flapping plate is G, G=6D, where D represents the diameter of the vortex-induced cylindrical oscillator, the length from the leading edge to the trailing edge of the flexible flapping plate is 3D, and the dimensionless stiffness of the flexible wake flapping energy collection system is 0.4~0.

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2. The fluid kinetic energy harvesting device based on a vortex-vibrating cylinder and a flexible wake-beating plate according to claim 1, characterized in that, The flexible wake flapping energy collection system also includes a shaft connected to the leading edge of the flexible flapping plate, and the shaft is rotatably supported on the bracket.

3. The fluid kinetic energy harvesting device based on a vortex-vibrating cylinder and a flexible wake-beating plate according to claim 2, characterized in that, The shaft is connected to the bracket via a rotating component.

4. The fluid kinetic energy harvesting device based on a vortex-vibrating cylinder and a flexible wake-beating plate according to claim 3, characterized in that, There are two rotating components, which are respectively connected to the upper and lower ends of the shaft, and are also connected to the bracket.

5. The fluid kinetic energy harvesting device based on a vortex-vibrating cylinder and a flexible wake-beating plate according to claim 1, characterized in that, The piezoelectric structure includes a piezoelectric layer, which is fixed to the flexible flapping plate.

6. The fluid kinetic energy harvesting device based on a vortex-vibrating cylinder and a flexible wake-beating plate according to claim 5, characterized in that, The piezoelectric structure further includes a substrate layer, which is attached to the flexible flapping plate, and the piezoelectric layer is attached to the substrate layer.

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