Tidal current energy collection method and device

Abstract

According to the tidal current energy collecting method and device, the energy harvesting efficiency of the tidal current energy can be effectively evaluated, meanwhile, a design thought can be provided for improving the tidal current energy harvesting efficiency, and the energy harvesting efficiency is further improved in combination with the oscillating wing type tidal current energy efficient collecting device.

Description

Technical Field

[0001] The present invention relates to the technical field of ships and marine engineering, and in particular to a tidal energy collection method and device. Background Art

[0002] Compared with propulsion turbines or other turbine designs, oscillating hydrofoil tidal energy turbines have the following advantages and characteristics in the field of tidal energy power generation: strong adaptability, simple structure, high reliability, high flexibility, high energy conversion efficiency, multi-purpose application, low noise and space saving, etc. Therefore, it is very necessary to research and develop oscillating hydrofoil tidal energy turbines.

[0003] Thanks to the development of science and technology, there are many new energy capture methods available, but there are generally problems such as low energy capture efficiency and poor economy. The efficient energy capture of the series oscillating blade tidal energy turbine will face complex flow fields, interactions between components and response speeds that will affect the damping characteristics of the power output (PTO) system, design and manufacturing challenges, as well as durability and reliability challenges. Summary of the invention

[0004] The technical problem to be solved by the technical solution of the present invention is: how to optimize the energy conversion efficiency of the series oscillating blade type tidal current energy turbine.

[0005] The technical solution of the present invention provides a tidal energy collection method, comprising the following steps:

[0006] Formulate an overall research plan for the series oscillating blade turbine based on the preliminary budget obtained from the survey;

[0007] According to the potential flow theory, the mechanical transmission and spatial layout design of the overall research plan of the series oscillating blade turbine and the preliminary design of the inertial mechanism and hydraulic PTO system were carried out to obtain the conceptual design plan of the series oscillating blade turbine system;

[0008] The conceptual design scheme of the series oscillating blade turbine system is subjected to nonlinear time-domain coupling dynamics analysis and frequency-domain coupling dynamics analysis. The nonlinear time-domain coupling dynamics analysis obtains the motion response and load characteristics under typical working conditions, and the frequency-domain coupling dynamics analysis obtains the motion response and power output response. The design parameters of the series oscillating blade tidal energy turbine are obtained based on the motion response and power output response and the motion response and load characteristics.

[0009] According to the design parameters of the series oscillating blade tidal energy turbine, the energy conversion efficiency target optimization study was carried out to obtain the design parameters of the optimal conversion efficiency solution;

[0010] According to the design parameters of the optimal conversion efficiency solution, it is applied to the series oscillating blade tidal energy turbine to collect tidal energy.

[0011] Preferably, in the potential flow theory, the NS equation is used as the control equation, and the turbulent kinetic energy and the turbulent kinetic energy dissipation rate are used as iterative parameters for initialization solution, and the initialization solution algorithm adopts a high-precision algorithm in a semi-implicit algorithm (PISO) format.

[0012] Preferably, the numerical results obtained by the initialization solution are presented in the form of post-processing results obtained by post-processing the vortex cloud map, and the post-processing process includes analyzing the oscillation characteristics of the oscillation wing under variable factors of different oscillation wing angles and different connecting column lengths according to the characteristics of the vortex cloud map.

[0013] Preferably, the NS equation is in the form of an unsteady equation, specifically as follows:

[0014]

[0015] Where ρ is the fluid density, is the characteristic variable, t is the time characterizing the non-steady nature of the flow field, V is the velocity vector, is the source term of the system of equations.

[0016] The technical solution of the present invention also provides a tidal energy collection device, which adopts a tidal energy collection method as described above, and the tidal energy collection device comprises: a small-scale single pile, a connecting column and a series oscillating hydrofoil, the small-scale single pile is fixed to the seabed and the top of the single pile is located above the water surface, and a movable swing mechanism is provided on the small-scale single pile, and the movable swing mechanism can perform pitch motion around the horizontal axis and simple harmonic motion around the vertical axis;

[0017] The serial oscillating hydrofoil is a rigid structure with a streamlined outer shell, including a plurality of oscillating wings connected in series. When the number of oscillating wings arranged is 2, the angle formed between the two oscillating wings is 90°. When the number of oscillating wings arranged is N and N is not less than 3, the angle formed between adjacent oscillating wings in the serial oscillating hydrofoil is 180° / N.

[0018] The connecting column is connected to the small-scale single pile by connecting to the movable swing mechanism, and is connected to the oscillating wing to achieve the connection between the serial oscillating hydrofoils and the connection between the serial oscillating hydrofoils and the small-scale single pile.

[0019] Preferably, a flow field boundary is applied to the tidal energy collection device, and the flow field boundary includes a velocity inlet, a pressure outlet, an oscillation wing, an oscillation control equation of a connecting column connecting the oscillation wing, and a wall boundary of a single column.

[0020] Preferably, the pitch motion equation adopts a polar coordinate system, and the control equation is the motion equation of the wave surface; the simple harmonic motion equation adopts a rectangular coordinate system, and the control equation is the vortex-induced motion equation induced by the pressure gradient formed by the shedding of the wake vortex.

[0021] Preferably, the diameter of the small-scale single pile does not exceed 2 m.

[0022] Preferably, the length of the connecting column is no more than 1.5 times the chord length of the cross-sectional airfoil of the oscillating wing, and no less than 1 times the chord length of the cross-sectional airfoil. The connecting columns are independent of each other, and the movements of the series-connected oscillating hydrofoils connected by the connecting columns are independent of each other.

[0023] Preferably, the axial direction of the series oscillating hydrofoil remains parallel to the direction of the connecting column, the two ends of the connecting column are in the same horizontal plane as the surface of the series oscillating hydrofoil and the small-sized single column, and the series oscillating hydrofoil and the connecting column are fixed at the fluid stagnation point position of the series oscillating hydrofoil.

[0024] The technical solution of the present invention proposes a tidal energy collection method and device that can effectively evaluate the energy capture efficiency of tidal energy, and at the same time can provide design ideas for improving the tidal energy capture efficiency. Combined with an oscillating wing-type tidal energy high-efficiency collection device provided by the technical solution of the present invention, the energy capture efficiency is further improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A flow chart of a tidal energy collection method provided by an embodiment of the present invention;

[0026] Figure 2 A three-dimensional conceptual schematic diagram of an oscillating wing in a tidal current energy efficient collection device in the form of an oscillating wing provided in an embodiment of the present invention;

[0027] Figure 3 A schematic diagram of the structure of an oscillating wing in a tidal current energy efficient collection device in the form of an oscillating wing provided in an embodiment of the present invention;

[0029] 1: Small-scale single pile, 2: Connecting column, 3: Oscillation wing. DETAILED DESCRIPTION

[0030] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0031] like Figure 1 As shown, an embodiment of the present invention provides a tidal energy collection method, which is applied to an offshore area rich in tidal energy, and includes the following steps:

[0032] Formulate the overall research plan of series oscillating blade turbine based on the preliminary budget obtained from the research;

[0033] According to the potential flow theory, the mechanical transmission and spatial layout design of the overall research plan of the series oscillating blade turbine and the preliminary design of the inertial mechanism and hydraulic PTO system were carried out to obtain the conceptual design plan of the series oscillating blade turbine system;

[0034] The conceptual design of the series oscillating blade turbine system is analyzed by nonlinear time-domain coupling dynamics analysis and frequency-domain coupling dynamics analysis. The motion response and load characteristics under typical working conditions are obtained by nonlinear time-domain coupling dynamics analysis, and the motion response and power output response are obtained by frequency-domain coupling dynamics analysis. The design parameters of the series oscillating blade tidal current energy turbine are obtained according to the motion response and power output response.

[0035] According to the design parameters of the series oscillating blade tidal current energy turbine, the energy conversion efficiency target optimization study was conducted to obtain the optimization scheme of the series oscillating blade tidal current energy turbine.

[0036] In the mechanical transmission and spatial layout design of the overall research plan of the series oscillating blade turbine, the NS (Navier-Stokes) equations are used as the control equations, and the turbulent kinetic energy and turbulent kinetic energy dissipation rate in the flow field are used as iterative parameters for initialization and solution. The initialization solution algorithm adopts a high-precision algorithm in PISO format.

[0037] The NS equation is in the form of an unsteady equation, as follows:

[0038]

[0039] Where ρ is the fluid density. This example is seawater. is the characteristic variable in this case, which is the turbulence intensity, t is the time to characterize the unsteadiness of the flow field, V is the velocity vector, is the source term of the system of equations.

[0040] The flow field boundary is imposed on the series oscillating blade tidal energy turbine model, and the flow field boundary includes the velocity inlet, the pressure outlet, the oscillating blade, the oscillation control equation of the connecting column connecting the oscillating blade, and the wall boundary of the single column.

[0041] The post-processing results obtained by post-processing the vorticity cloud map are presented in the form of post-processing results. The post-processing process includes analyzing the oscillation characteristics of the oscillating wing under variable factors of different oscillation wing angles and different connecting column lengths according to the characteristics of the vorticity cloud map.

[0042] The model of the cascade oscillating blade tidal current energy turbine is established using the overlapping grid method. The overlapping grid is applied around the symmetrically set oscillating blades and moves with the movement of the oscillating blades.

[0043] The embodiment of the present invention also provides a tidal energy efficient collection device in the form of an oscillating wing, which adopts a tidal energy collection method as described above, including: a small-scale single pile 1, a connecting column 2, and a series of oscillating hydrofoils. The three-dimensional concept of the oscillating wing in the series of oscillating hydrofoils is as follows: Figure 2 As shown, the oscillating wing structure in the series oscillating hydrofoil is as follows Figure 3 shown.

[0044] The serial oscillating hydrofoil uses passive control to achieve the conversion of tidal kinetic energy. The conversion of tidal kinetic energy is completed through the hydraulic PTO system.

[0045] The small-scale single pile 1 is fixed to the seabed and the top of the single pile is above the water surface, and its diameter does not exceed 2m. The small-scale single pile 1 is provided with a movable swing mechanism, which can realize rotation around the horizontal axis and the vertical axis. The rotation around the horizontal axis is a pitch motion, and the control equation of its motion is the motion equation of the wave surface. The rotation around the vertical axis is a simple harmonic motion, and the control equation of its motion is the motion induced by the pressure gradient formed by the vortex shedding of the wake.

[0046] The connecting column 2 is used to connect the small-scale single pile 1 and the series oscillating hydrofoil, and to connect the adjacent oscillating wings 3 of the series oscillating hydrofoil. The connecting column 2 is connected to the movable swinging mechanism. The number of oscillating wings 3 connected by the connecting column 2 is not less than 2 and is arranged vertically. The length of the connecting column 2 does not exceed 1.5 times the chord length of the airfoil cross-section of the oscillating wing 3, and is not less than 1 times the chord length.

[0047] The oscillation control equation of the series oscillating hydrofoil and the connecting column 2 is the simple harmonic motion equation of the rotation angle, as follows:

[0048] θ t =θ0sin(2πft)

[0049] Among them, θ t is the instantaneous rotation angle, θ0 is the maximum rotation angle, f is the oscillation frequency of the oscillating wing, t is the flow field time variable, and the polar coordinate pitch motion equation of the oscillating wing is: t =Rcos(γcos(2πft)),y t = Rsin(γcos(2πft)), where γ = arcsin(H0 / R), where x t ,y t is the polar coordinate of the rotational oscillating wing, R is the length of the connecting column, and H0 is the height of the pitching motion.

[0050] The axial direction of the series oscillating hydrofoil is parallel to the direction of the connecting column 2, the series oscillating hydrofoil and the connecting column 2 are arranged on the same plane, the series oscillating hydrofoil is a rigid structure, and the series oscillating hydrofoil and the connecting column 2 are fixed at the fluid stagnation point position of the series oscillating hydrofoil.

[0051] The fluid stagnation point is a point in the flow field where the fluid velocity around the object being flowed around is 0, and in this embodiment, it is the leading edge of the oscillating wing.

[0052] The shell of the serial oscillating hydrofoil is streamlined. When the number of the oscillating wings 3 arranged in the serial oscillating hydrofoil is 2, the angle formed between the oscillating wings 3 in the serial oscillating hydrofoil is 90°.

[0053] When the number of oscillation wings 3 in the serial oscillation hydrofoil is N and N is not less than 3, the angle formed between adjacent oscillation wings 3 in the serial oscillation hydrofoil is 180° / N.

[0054] A tidal energy collection method and device proposed in an embodiment of the present invention can effectively evaluate the energy capture efficiency of tidal energy, and at the same time can provide design ideas for improving the tidal energy capture efficiency. Combined with an oscillating wing-type tidal energy high-efficiency collection device provided in an embodiment of the present invention, the energy capture efficiency can be further improved.

Claims

1. A tidal current energy collection method, characterized in that: The following steps are involved: Formulate an overall research plan for the series oscillating blade turbine based on the preliminary budget obtained from the survey; According to the potential flow theory, the mechanical transmission and spatial layout design of the overall research plan of the series oscillating blade turbine and the preliminary design of the inertial mechanism and hydraulic PTO system were carried out to obtain the conceptual design plan of the series oscillating blade turbine system; The conceptual design scheme of the series oscillating blade turbine system is subjected to nonlinear time-domain coupling dynamics analysis and frequency-domain coupling dynamics analysis. The nonlinear time-domain coupling dynamics analysis obtains the motion response and load characteristics under typical working conditions, and the frequency-domain coupling dynamics analysis obtains the motion response and power output response. The design parameters of the series oscillating blade tidal energy turbine are obtained based on the motion response and power output response and the motion response and load characteristics. According to the design parameters of the series oscillating blade tidal energy turbine, the energy conversion efficiency target optimization study was carried out to obtain the design parameters of the optimal conversion efficiency solution; According to the design parameters of the optimal conversion efficiency solution, it is applied to the series oscillating blade tidal energy turbine to collect tidal energy.

2. A tidal current energy collection method as claimed in claim 1, characterized in that: The potential flow theory uses the NS equation as the control equation, and uses the turbulent kinetic energy and the turbulent kinetic energy dissipation rate as iterative parameters for initialization solution. The initialization solution algorithm adopts a high-precision algorithm in a semi-implicit algorithm (PISO) format.

3. A tidal current energy collection method as claimed in claim 2, characterized in that: The numerical results obtained by the initialization solution are presented in the form of post-processing results obtained by post-processing the vorticity cloud map. The post-processing process includes analyzing the oscillation characteristics of the oscillating wing under variable factors of different oscillation wing angles and different connecting column lengths according to the characteristics of the vorticity cloud map.

4. A tidal current energy collection method as claimed in claim 2, characterized in that: The NS equation is in the form of an unsteady equation, as follows: Where ρ is the fluid density, is the characteristic variable, t is the time characterizing the non-steady nature of the flow field, V is the velocity vector, is the source term of the system of equations.

5. A tidal energy collection device, characterized in that: A tidal current energy collection method as claimed in claim 1 is adopted, wherein the tidal current energy collection device comprises: a small-scale monopile, a connecting column and a series-type oscillating hydrofoil, wherein the small-scale monopile is fixed to the seabed and the top of the monopile is located above the water surface, and a movable swing mechanism is provided on the small-scale monopile, and the movable swing mechanism can perform pitch motion around a horizontal axis and simple harmonic motion around a vertical axis; The serial oscillating hydrofoil is a rigid structure with a streamlined outer shell, including a plurality of oscillating wings connected in series. When the number of oscillating wings arranged is 2, the angle formed between the two oscillating wings is 90°. When the number of oscillating wings arranged is N and N is not less than 3, the angle formed between adjacent oscillating wings in the serial oscillating hydrofoil is 180° / N. The connecting column is connected to the small-scale single pile by connecting to the movable swing mechanism, and is connected to the oscillating wing to achieve the connection between the serial oscillating hydrofoils and the connection between the serial oscillating hydrofoils and the small-scale single pile.

6. A tidal current energy collection device as claimed in claim 5, characterized in that: A flow field boundary is applied to the tidal energy collection device, wherein the flow field boundary includes a velocity inlet, a pressure outlet, an oscillation wing, an oscillation control equation of a connecting column connecting the oscillation wing, and a wall boundary of a single column.

7. A tidal current energy collection device as claimed in claim 5, characterized in that: The pitch motion equation adopts a polar coordinate system, and the control equation is the motion equation of the wave surface. The simple harmonic motion equation adopts a rectangular coordinate system, and the control equation is the vortex-induced motion equation induced by the pressure gradient formed by the shedding of the wake vortex.

8. A tidal current energy collection device as claimed in claim 5, characterized in that: The diameter of the small-scale single pile does not exceed 2m.

9. A tidal current energy collection device as claimed in claim 5, characterized in that: The length of the connecting column is no more than 1.5 times the chord length of the cross-sectional airfoil of the oscillating wing, and no less than 1 times the chord length of the cross-sectional airfoil. The connecting columns are independent of each other, and the movements of the serially connected oscillating hydrofoils connected by the connecting columns are independent of each other.

10. A tidal current energy collection device as claimed in claim 4, characterized in that: The axial direction of the series oscillating hydrofoil remains parallel to the direction of the connecting column, the two ends of the connecting column are in the same horizontal plane as the surface of the series oscillating hydrofoil and the small-sized single column, and the series oscillating hydrofoil and the connecting column are fixed at the fluid stagnation point position of the series oscillating hydrofoil.

Images