Method and system for calculating two-dimensional flow field of vertical axis wind turbine

Abstract

The invention provides a two-dimensional flow field calculation method and system for a vertical axis wind turbine, and relates to the technical field of computational fluid mechanics, and the method comprises the steps: building a two-dimensional numerical model for a middle plane of the vertical axis wind turbine; based on the two-dimensional numerical model, determining a two-dimensional flow field of the vertical axis wind turbine at the current moment; according to the two-dimensional flow field, blade lift force is determined; generating a target blade tip vortex element, and calculating the strength of the target blade tip vortex element through the Rogowski lift theorem; updating the position and strength of the vortex element of the blade tip vortex; traversing all grids in the two-dimensional flow field drainage basin based on the updated blade tip vortex elements, and for each grid, calculating the blade tip vortex induced velocity of the position where the grid is located; calculating and applying a required mass source item and a required momentum source item according to the induced velocity; and after the preset updating frequency is reached, outputting a calculation result. The calculation amount is reduced, and the calculation efficiency and accuracy are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of computational fluid dynamics, in particular to a two-dimensional flow field calculation method and system for a vertical axis wind turbine. BACKGROUND

[0002] The two-dimensional flow field calculation method for a vertical axis wind turbine uses computational fluid dynamics (CFD) technology to simulate the airflow distribution around the wind turbine blades and their interaction through a simplified two-dimensional model, usually involving turbulence models, grid division, iterative calculation, etc., to help analyze and optimize wind turbine design and improve wind turbine energy conversion efficiency.

[0003] Due to the complex aerodynamic characteristics of the vertical axis wind turbine blades, the tip vortex and flow field induction effect have a serious impact on lift and drag, and a full-size three-dimensional numerical model is required to simulate the complete three-dimensional flow field to accurately calculate the aerodynamic characteristics of the vertical axis wind turbine.

[0004] However, the traditional three-dimensional numerical model has a very large amount of calculation, and when simulating the complete three-dimensional flow field, the required computing resources and time are extremely expensive, making it difficult to carry out large-scale wind turbine design optimization in actual engineering. The existing vertical axis wind turbine flow field evolution usually uses a two-dimensional numerical model that can reduce the complexity of the calculation, which can effectively reduce the calculation cost, and has important practical application value for wind turbine design, optimization and improvement of wind energy conversion efficiency, but the existing two-dimensional numerical model cannot fully consider the complex phenomena in the flow field, resulting in deviation of the calculation results and inaccurate performance prediction of the wind turbine. SUMMARY

[0005] In view of the above deficiencies of the prior art, the purpose of the embodiments of the present application is to provide a two-dimensional flow field calculation method for a vertical axis wind turbine, which can solve the technical problems that the traditional three-dimensional numerical model has a very large amount of calculation, and when simulating the complete three-dimensional flow field, the required computing resources and time are extremely expensive, making it difficult to carry out large-scale wind turbine design optimization in actual engineering, and the existing vertical axis wind turbine flow field evolution usually uses a two-dimensional numerical model that can reduce the complexity of the calculation, but the existing two-dimensional model cannot fully consider the complex phenomena in the flow field, resulting in deviation of the calculation results and inaccurate performance prediction of the wind turbine.

[0006] The first aspect of the embodiments of the present application proposes a two-dimensional flow field calculation method for a vertical axis wind turbine, comprising:

[0007] S1: establishing a two-dimensional numerical model for the middle plane of the vertical axis wind turbine;

[0008] S2: determining the two-dimensional flow field of the vertical axis wind turbine at the current time based on the two-dimensional numerical model;

[0009] S3: determining a blade lift according to the two-dimensional flow field;

[0010] S4: generating a target blade tip vortex element, and calculating a strength of the target blade tip vortex element by Joukowski's lift theorem according to the blade lift;

[0011] S5: updating a position and the strength of the target blade tip vortex element according to a motion state of the blade tip vortex;

[0012] S6: traversing all grids in a flow field domain based on the updated target blade tip vortex element, and calculating a blade tip vortex induced velocity at a position of each grid;

[0013] S7: calculating and applying a required mass source term and a momentum source term according to the blade tip vortex induced velocity;

[0014] S8: judging whether a preset updating number is reached; if yes, outputting a two-dimensional flow field calculation result including a velocity distribution and a blade aerodynamic force based on the mass source term and the momentum source term; otherwise, returning to step S2.

[0015] A second aspect of the embodiment of the present application provides a two-dimensional flow field calculation system of a vertical axis wind turbine, comprising a processor and a memory.

[0016] The memory stores programs or instructions executable on the processor, and the programs or instructions are executed by the processor to implement the steps of the two-dimensional flow field calculation method of the vertical axis wind turbine according to the first aspect.

[0017] A third aspect of the embodiment of the present application provides a readable storage medium, and the readable storage medium stores programs or instructions, and the programs or instructions are executed by a processor to implement the steps of the two-dimensional flow field calculation method of the vertical axis wind turbine according to the first aspect.

[0018] The technical scheme provided by the embodiment of the present application has at least the following beneficial effects:

[0019] In the embodiment of the application, the complexity of the three-dimensional model is simplified by establishing a two-dimensional numerical model, the calculation amount is reduced, the calculation efficiency is greatly improved, the formation and strength of the tip vortex are accurately estimated by introducing the Joukowski lift theorem and calculating the tip vortex strength, and then the vortex element is generated in the model, so that the model can more accurately capture the influence of the tip vortex on the flow field, the change of the vortex flow is tracked in real time by updating the position and strength of the vortex element, and the influence of the vortex flow on the flow field is fed back to the calculation, so that the calculation result can more reflect the real wind turbine running state, more accurate performance prediction is provided, the mass source term and the momentum source term are determined and applied by traversing all the grids in the two-dimensional flow field basin, the interaction of the fluid around the wind turbine blade is considered comprehensively, the accuracy of the flow field is improved, the design of the wind turbine blade is optimized, better aerodynamic performance is ensured, the balance between the calculation accuracy and the calculation time is ensured by setting the preset update number, and the problems of excessive calculation or insufficient calculation accuracy are avoided. BRIEF DESCRIPTION OF DRAWINGS

[0020] The accompanying drawings are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the principles of the application. In the drawings:

[0021] Figure 1 FIG. 1 is a flow diagram of a two-dimensional flow field calculation method of a vertical axis wind turbine according to an embodiment of the application;

[0022] Figure 2 FIG. 2 is a schematic diagram of a vertical axis wind turbine and a two-dimensional numerical model of the middle plane according to an embodiment of the application;

[0023] Figure 3 FIG. 3 is a schematic diagram of a tip vortex of a vertical axis wind turbine and an induced action thereof according to an embodiment of the application;

[0024] Figure 4 FIG. 4 is a structural diagram of a two-dimensional flow field calculation system of a vertical axis wind turbine according to an embodiment of the application. DETAILED DESCRIPTION

[0025] In the following, the technical solutions of the present application will be described clearly and completely in connection with the drawings, obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. It should be understood that these descriptions are only exemplary, and are not used to limit the scope of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor should belong to the scope of protection of the present application.

[0026] In the following, the technical solutions of the present application will be described clearly and completely in connection with the drawings, obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. It should be understood that these descriptions are only exemplary, and are not used to limit the scope of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor should belong to the scope of protection of the present application.

[0027] Reference is made to the accompanying drawings Figure 1 , a flowchart of a two-dimensional flow field calculation method of a vertical axis wind turbine is shown;

[0028] The embodiment of the present application provides a two-dimensional flow field calculation method of a vertical axis wind turbine, which can include the following steps:

[0029] Reference is made to the accompanying drawings Figure 2 , a vertical axis wind turbine and a two-dimensional numerical model of the middle plane thereof provided by the embodiment of the present application are shown.

[0030] As shown in Figure 2 , the left part shows the overall structure of the vertical axis wind turbine, including the support frame, the blade and the water surface of the wind turbine, and highlights the yaw (yaw angle), surge (longitudinal displacement), roll (roll angle) and other movements of the wind turbine. The right part of the figure refines the two-dimensional flow field model of the wind turbine, and shows the flow field distribution generated by the wind turbine blade in the fluid.

[0031] S1: establishing a two-dimensional numerical model for the middle plane of the vertical axis wind turbine, wherein the vertical axis wind turbine includes a plurality of blades, and the blades are used to generate tip vortex by rotating.

[0032] In the present application, the two-dimensional numerical model for the middle plane of the vertical axis wind turbine is established by fluid mechanics theory.

[0033] Wherein, the fluid mechanics theory is the science of studying fluid (such as gas or liquid) and its interaction with objects, and its theory includes the basic equations of fluid, such as Navier-Stokes equation, Bernoulli equation and the like, which are used to describe the motion state, pressure change and velocity distribution of fluid. The vertical axis wind turbine (VAWT) is a kind of wind turbine, and the wind wheel thereof rotates around the vertical axis. Different from the traditional horizontal axis wind turbine, the blades of the vertical axis wind turbine can receive wind power in any direction, and have strong adaptability, and can operate under various wind speed and wind direction conditions. The two-dimensional numerical model is to simplify the three-dimensional space, and limit the calculation of the flow field of the wind turbine in a two-dimensional plane. The blade is the core part of the wind turbine, which captures wind energy and converts it into mechanical energy to drive the wind turbine to rotate, and the design of the blade affects the efficiency and performance of the wind turbine. The tip vortex is the vortex generated at the tip of the blade when the wind turbine blade rotates, due to the relative motion between the blade and the air, the airflow is deflected at the tip position, forming rotating vortex, and these vortexes have an impact on the performance of the wind turbine, and usually cause energy loss.

[0034] It should be noted that by establishing a two-dimensional numerical model based on fluid mechanics theory to simulate the flow field of the vertical axis wind turbine, the calculation process can be effectively simplified, the calculation complexity can be reduced, the aerodynamic performance of the blade can be predicted, and the design of the wind turbine can be optimized in a reasonable precision range.

[0035] S2: determining the two-dimensional flow field of the vertical axis wind turbine at the current time based on the two-dimensional numerical model.

[0036] In the present application, the two-dimensional flow field of the vertical axis wind turbine at the current time is determined by the transient calculation mode.

[0037] Wherein, the transient calculation mode refers to considering the time change factor in the simulation process, and gradually calculating the change of the flow field. The transient calculation mode can simulate the dynamic change of fluid at each time step, and is suitable for the case that the flow field changes with time. The two-dimensional flow field is the flow state of fluid in a two-dimensional plane, which describes the distribution of velocity, pressure and other physical quantities of fluid in the plane.

[0038] Specifically, by using the two-dimensional numerical model combined with the transient calculation mode, the flow field change of the vertical axis wind turbine at different time steps can be dynamically simulated. Through transient calculation, the instantaneous flow change of the wind turbine during operation can be more accurately captured, and the two-dimensional model effectively reduces the calculation complexity and resource consumption, so that even large-scale wind turbine design optimization can be completed in a short time.

[0039] In one possible implementation, the two-dimensional flow field includes: velocity distribution and pressure distribution.

[0040] The velocity distribution refers to the distribution of the flow velocity and direction of each point in a certain region, represents the motion state of the fluid in space, and is usually expressed in the form of a velocity vector. In the calculation of the flow field of a wind turbine, the velocity distribution is used to describe the change in velocity of air flowing through the blades of the wind turbine and the surrounding area, reflecting the aerodynamic characteristics of the wind turbine and the interaction between the fluid and the blades. The pressure distribution refers to the distribution of the pressure value of each point in a certain region, and describes the change in pressure of the fluid in space. In the calculation of the two-dimensional flow field of a wind turbine, the pressure distribution is used to analyze the change in pressure on the surface of the blades of the wind turbine.

[0041] In a possible implementation, S2 specifically comprises:

[0042] S201: setting a time step according to the rotation angle of the rotor of the vertical-axis wind turbine.

[0043] S202: determining the two-dimensional flow field of the vertical-axis wind turbine at the current time through iterative calculation according to the time step.

[0044] It should be noted that, by setting a time step according to the rotation angle of the rotor of the vertical-axis wind turbine and dynamically simulating the two-dimensional flow field of the wind turbine through iterative calculation, the change in the flow field of the wind turbine at different rotation angles can be accurately reflected, the instantaneous flow effect can be captured, the interaction between the blades and the airflow can be effectively considered, and through iterative calculation, a more accurate flow field distribution can be gradually obtained, thereby ensuring the accuracy of the calculation result.

[0045] In the present application, the flow field calculation adopts a transient mode, and each rotation of 0.25° of the rotor is set as a time step. In a time step, the flow field at the current time is first obtained through iterative calculation, including the velocity distribution, the pressure distribution, etc.

[0046] S3: determining the lift of the blade according to the two-dimensional flow field.

[0047] In a possible implementation, S3 specifically comprises:

[0048] S301: calculating the relative flow velocity and the angle of attack of the blade according to the position of the blade and the flow velocity of the fluid.

[0049] S302: extracting the surface pressure of the blade according to the pressure distribution, and integrating the surface pressure.

[0050] S303: calculating the lift of the blade according to the relative flow velocity, the angle of attack, and the integrated surface pressure.

[0051] S4: generating a target tip vortex element, and calculating the strength of the target tip vortex element through the Joukowski lift theorem according to the lift of the blade.

[0052] Wherein, Joukowski's lift theorem is a basic theorem in aerodynamics, which is used to describe the principle of lift generated by rotating objects (such as wind turbine blades) in fluid, and the theorem points out that the lift is proportional to the flow velocity and the vortex ring intensity (the strength of vortex flow). The tip vortex element is a discrete unit of tip vortex, and in order to calculate the influence of tip vortex in the flow field, it is usually decomposed into multiple vortex elements.

[0053] It should be noted that by using Joukowski's lift theorem, the target tip vortex element is generated based on the fluid flow velocity, and the strength of the vortex element is accurately calculated, which can effectively simulate the formation of tip vortex and its influence on the flow field, ensure more accurate flow field calculation, and by decomposing the tip vortex into multiple vortex elements, the calculation can be refined to improve the simulation accuracy, avoid direct calculation of complex three-dimensional vortex flow, reduce the calculation complexity, and improve the calculation efficiency.

[0054] In one possible implementation, S4 specifically includes:

[0055] S401: generating a target tip vortex element at the tip of the blade.

[0056] S402: calculating the strength of the target tip vortex element according to the blade lift by Joukowski's lift theorem.

[0057] In one possible implementation, the calculation of the strength of the target tip vortex element in S402 specifically includes:

[0058] According to the following formula, the strength of the tip vortex element is estimated:

[0059] F l = ρ × V vel × Γ

[0060] Wherein, F l represents the blade lift, ρ represents the fluid density, V vel represents the relative flow velocity, and Γ represents the tip vortex intensity.

[0061] In the present application, it is assumed that the tip vortex intensity Γ is equal to the blade attached vortex intensity (both are relatively close in actual situation), and the calculation is performed according to Joukowski's lift theorem.

[0062] S5: updating the position and strength of the target tip vortex element according to the motion state of the tip vortex.

[0063] It should be noted that by dynamically updating the position and intensity of the tip vortex element, the changes in the vortex can be reflected in real time, and the movement of the tip vortex in the flow field can be accurately simulated. With the rotation of the wind turbine blade, the influence of the tip vortex changes continuously, and updating the motion state of the vortex element can ensure that the simulation process is consistent with the actual operation, accurately capture the time-varying effect of the vortex, improve the accuracy of the flow field calculation, and enhance the prediction ability of the blade aerodynamic performance.

[0064] Referring to the drawings accompanying the specification Figure 3 , a schematic diagram of the tip vortex of the vertical axis wind turbine and its induced effect is shown.

[0065] As Figure 3 , the middle plane of the wind turbine blade is shown, the wind speed V flows from the left side, and interacts with the tip vortex generated by the rotation of the blade. In the figure, a plurality of key points and variables are labeled: V rel represents the relative velocity of the blade, F l is the lift of the blade, the tip vortex intensity Γ is represented as a vortex element pointed by the arrow, each vortex element is generated along the edge of the blade and induces a velocity V ind , the figure also includes the geometric relationship between the vortex elements and the calculation points at different distances, as well as the direction and influence of the induced velocity. Overall, the figure demonstrates the generation mechanism of the tip vortex and its influence on the flow field in the middle plane, helping to understand the complex aerodynamic interaction between the wind turbine blade and the fluid.

[0066] S6: Based on the updated target tip vortex element, traverse all grids in the two-dimensional flow field domain and calculate the tip vortex induced velocity at the position of each grid.

[0067] Wherein, the two-dimensional flow field domain refers to a spatial region used to simulate the flow of the wind turbine, which is usually discretized by two-dimensional grids to calculate the flow state of the fluid around the wind turbine blade, including velocity, pressure and vortex, etc. Physical quantities.

[0068] In one possible implementation, in S6, the induced velocity includes: normal induced velocity, transverse induced velocity and longitudinal induced velocity.

[0069] Wherein, the induced velocity refers to the influence of the vortex on the flow field, which represents the change of the fluid velocity caused by the existence of the tip vortex element. The induced velocity is usually determined by calculating the effect of the vortex on the fluid at a certain position.

[0070] Specifically, by accurately calculating the different directional velocity components of the vortex element on the flow field, the influence of the vortex on the fluid can be comprehensively captured, the effects of the blade on the flow field in all directions can be accurately simulated, the accuracy of the flow field calculation is improved, in addition, the induced velocity can effectively reflect the influence of the vortex on the performance of the wind turbine, and accurate data is provided for optimization design and performance evaluation.

[0071] In a possible implementation, S6 specifically includes:

[0072] The induced velocity is calculated by the Biot-Savart law formula.

[0073] In a possible implementation, the normal induced velocity specifically includes: a first normal induced velocity, a second normal induced velocity, a third normal induced velocity, and a fourth normal induced velocity.

[0074] The normal induced velocity is specifically:

[0075] V ind,z = V ind,z1 + V ind,z2 + V ind,z3 + V ind,z4

[0076]

[0077] d 2,i = (y p -y i )cos theta - (x p -x i )sin theta

[0078]

[0079] Wherein, V ind,z represents the normal induced velocity, V ind,z1 represents the first normal induced velocity, V ind,z2 represents the second normal induced velocity, V ind,z3 represents the third normal induced velocity, V ind,z4 represents the fourth normal induced velocity, r i represents, i = 0, 1, …, n, n represents the total number of first blade tip vortex elements, l represents the length of the blade tip vortex, d 3,i represents the spatial distance from the induction point to the tangent of the vortex element, H represents the length of the wind turbine blade, Γ i represents the strength of the blade tip vortex element, d 1,i represents the horizontal distance from the induction point to the vortex element, d 2,i represents the horizontal distance from the induction point to the tangent of the vortex element, x p , y p and z py represents the coordinate of the induced point near the middle plane, y i x represents the longitudinal coordinate of the vortex element i, x i θ represents the azimuth angle of the blade when the tip vortex vortex element is shed.

[0080] The lateral induction velocity specifically includes: a first lateral induction velocity, a second lateral induction velocity, a third lateral induction velocity, and a fourth lateral induction velocity.

[0081] The lateral induction velocity specifically is:

[0082] V ind,x = V ind,x1 + V ind,x2 + V ind,x3 + V ind,x4

[0083]

[0084] wherein V ind,x represents the lateral induction velocity, V ind,x1 represents the first lateral induction velocity, V ind,x2 represents the second lateral induction velocity, V ind,x3 represents the third lateral induction velocity, and V ind,x4 represents the fourth lateral induction velocity.

[0085] The longitudinal induction velocity specifically includes: a first longitudinal induction velocity, a second longitudinal induction velocity, a third longitudinal induction velocity, and a fourth longitudinal induction velocity.

[0086] The longitudinal induction velocity specifically is:

[0087] V ind,y = V ind,y1 + V ind,y2 + V ind,y3 + V ind,y4

[0088]

[0089] wherein V ind,y1 represents the longitudinal induction velocity, V ind,y1 represents the first longitudinal induction velocity, V ind,y2 represents the second longitudinal induction velocity, V ind,y3 represents the third longitudinal induction velocity, and V ind,y4 represents the fourth longitudinal induction velocity.

[0090] S7: According to the tip vortex induction velocity, the required mass source term and momentum source term are calculated and applied.

[0091] The mass source term represents the mass change or source-sink effect of the fluid in a specific area, and is used to describe the process of generating or consuming mass in the flow field in the fluid simulation. The momentum source term represents the change of momentum in the flow field caused by external force or pressure difference, and is usually used to simulate the pushing effect of vortex on fluid and the influence of vortex such as tip vortex on flow field.

[0092] It should be noted that by traversing all the grids in the two-dimensional flow field based on the updated tip vortex element, the mass source term and the momentum source term are determined and applied, which can accurately simulate the induction effect of the tip vortex in the flow field, and effectively reflect the acceleration and flow influence of the vortex on the fluid through the mass source term and the momentum source term. By traversing each grid point, the comprehensiveness and accuracy of the calculation result are ensured.

[0093] In a possible implementation, the mass source term is specifically:

[0094]

[0095] wherein S M represents the mass source term, p represents the fluid density, and h represents the distance from the induction point to the intermediate average.

[0096] The momentum source term is specifically:

[0097]

[0098] wherein f x and f y represent the transverse and longitudinal momentum source terms, and respectively represent the transverse and longitudinal accelerations, u x represents the flow velocity of the fluid in the x direction, and u y represents the flow velocity of the fluid in the y direction. represents the partial derivative operator.

[0099] In the present application, for a two-dimensional plane, the distribution and change of the induced velocity can be used to provide acceleration to the fluid particles by adding the momentum source term, so that the fluid velocity changes to achieve the effect of superimposing the induced velocity field, thereby equivalent to the induction effect of the tip vortex in the intermediate plane. The required change amount of the fluid velocity should be equal to the value of the local induced velocity. Since the two-dimensional calculation domain is large enough, the induced velocity at the boundary of the calculation domain is almost zero. If the initial effect of fluid acceleration is not considered, the acceleration required for the change of flow velocity should include two parts. One part is understood from the perspective of fluid particle motion. When the fluid particle moves from one position to the next position, the change amount of the induced velocity is the change amount of the velocity, at this time the time experienced is ds / u, and then the acceleration is The other part is understood from the instantaneous change of the induced velocity, when the fluid particle is at a certain position, if the local induced velocity is in the process of change (with time-varying acceleration) at this time, the acceleration of the fluid particle when passing through this position should be equal to the local acceleration of the induced velocity.

[0100] S8: judging whether the preset update number is reached. If yes, outputting the two-dimensional flow field calculation result including the velocity distribution and the blade aerodynamic force based on the mass source term and the momentum source term. Otherwise, returning to step S2.

[0101] It should be noted that by judging whether the preset update number is reached, the balance between the accuracy and the efficiency of the calculation process is ensured, the waste of calculation resources caused by excessive iteration is avoided, the accuracy and stability of the calculation result are ensured, the calculation process can be flexibly adjusted, the calculation time can be effectively controlled, and the calculation efficiency can be improved under the premise of ensuring the accuracy.

[0102] Referring to the accompanying drawings Figure 4 , a structure schematic diagram of a two-dimensional flow field calculation system of a vertical axis wind turbine provided by an embodiment of the present application is shown.

[0103] An embodiment of the present application provides a two-dimensional flow field calculation system 20 of a vertical axis wind turbine, which comprises a processor 201 and a memory 202.

[0104] The memory 202 stores programs or instructions which can run on the processor 201, and the programs or instructions are executed by the processor 201 to realize the steps of the two-dimensional flow field calculation method of the vertical axis wind turbine and achieve the same technical effects. To avoid repetition, the present application will not be described again.

[0105] It should be understood that the processor 201 in the embodiment of the present application can be a central processing unit (CPU), and the processor can also be other general-purpose processors, digital signal processors (DSP), application specific integrated circuits (ASIC), field programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor, etc.

[0106] It should also be understood that the memory 202 in embodiments of the present application can be volatile or nonvolatile memory, or can include both volatile and nonvolatile memory. Nonvolatile memory can be read-only memory (ROM), programmable ROM (PROM), erasable PROM (EPROM), electrically EPROM (EEPROM), or flash memory. Volatile memory can be random access memory (RAM), used as external cache. By way of example, and not limitation, many forms of random access memory (RAM) are available, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous dynamic RAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), Synchlink DRAM (SLDRAM), and direct rambus RAM (DR RAM).

[0107] The above-described embodiments can be implemented in part or in whole through software, hardware (e.g., circuitry), firmware, or any combination thereof. When implemented in software, the above-described embodiments can be implemented in the form of a computer program product. The computer program product includes one or more computer instructions or computer programs. When loaded and executed by a computer, the computer instructions or computer programs cause the computer to perform the processes or functions described above according to the embodiments of the present application. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable apparatus. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another computer-readable storage medium, such as from a website, a computer, a server, or a data center to another website, computer, server, or data center through a wired (e.g., infrared, wireless, microwave, or the like) manner. The computer-readable storage medium can be any available medium or a collection of medium accessible by a computer or a data storage device such as a server, data center, or the like, containing one or more of the available medium. The available medium can be a magnetic medium (e.g., a floppy diskette, a hard disk, a magnetic tape), an optical medium (e.g., a DVD), or a semiconductor medium. The semiconductor medium can be a solid-state hard disk.

[0108] It should be understood that the size of the serial number of each process described above does not mean the order of execution, and the execution order of each process should be determined by its function and inherent logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0109] Those skilled in the art can realize that the units and algorithm steps of the examples described in conjunction with the embodiments disclosed herein can be realized in electronic hardware or a combination of computer software and electronic hardware. Whether the functions are realized in hardware or software depends on the specific application and design constraints of the technical solution. A person skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present application.

[0110] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described devices, apparatuses, and units can refer to the corresponding processes in the foregoing method embodiments, which will not be described here.

[0111] In several embodiments provided by the present application, it should be understood that the disclosed devices, apparatuses and methods can be implemented in other manners. For example, the embodiments of the apparatus described above are merely schematic. For example, the division of the units is only a logical function division. There can be another division manner for the actual implementation. For example, a plurality of units or components can be combined or integrated into another device, or some features can be ignored or not executed. In addition, the displayed or discussed mutual couplings or direct couplings or communication connections between different units, can be indirect couplings or communication connections through some interfaces, devices or units, and can be in electrical, mechanical or other forms.

[0112] The units described as separate components can or can not be physically separate, and the components shown as units can or can not be physical units, i.e., can be located in one place, or can be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the embodiment.

[0113] In addition, each functional unit in the various embodiments of the present application can be integrated into a processing unit, or each unit can exist physically, or two or more units can be integrated into one unit.

[0114] If the functions are realized in the form of software function units and sold or used as independent products, they can be stored in a computer readable storage medium. Based on this understanding, the technical solutions of the present application or the part of the technical solutions that essentially contribute to the prior art can be embodied in the form of a software product. The computer software product is stored in a storage medium, and includes a plurality of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method described in the various embodiments of the present application. The aforementioned storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, and various media that can store program codes.

[0115] The embodiment of the present application provides a readable storage medium, which includes: a program or instruction stored on the readable storage medium, the program or instruction is executed by a processor to realize the steps of the two-dimensional flow field calculation method of the vertical axis wind turbine, and the same technical effect can be achieved. To avoid repetition, the present application will not be described again.

[0116] It should be pointed out finally that the above embodiments are only used to illustrate the technical solutions of the embodiments of the present application, but not to limit them. Although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features can be replaced equivalently; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application. Any changes or replacements that can be easily thought of by those skilled in the art within the technical scope disclosed by the present application should be covered within the protection scope of the present application.

Claims

1. A method of calculating a two-dimensional flow field of a vertical axis wind turbine, characterized by, The method comprises the following steps: S1: establishing a two-dimensional numerical model for the middle plane of a vertical axis wind turbine; S2: determining a two-dimensional flow field of the vertical axis wind turbine at the current time based on the two-dimensional numerical model; S3: determining blade lift according to the two-dimensional flow field; S4: generating a target tip vortex element, and calculating the strength of the target tip vortex element by Joukowski's theorem according to the blade lift; S5: updating the position and strength of the target tip vortex element according to the motion state of the tip vortex; S6: traversing all grids in the two-dimensional flow field based on the updated target tip vortex element, and calculating the tip vortex induced velocity at the position of each grid; S7: calculating and applying the required mass source term and momentum source term according to the tip vortex induced velocity; S8: determining whether the preset number of updates is reached; if yes, outputting the two-dimensional flow field calculation result including the velocity distribution and the blade aerodynamic force based on the mass source term and the momentum source term; otherwise, returning to step S2.

2. The method of calculating the two-dimensional flow field of a vertical axis wind turbine according to claim 1, characterized in that, The vertical axis wind turbine comprises a plurality of blades, and the blades generate tip vortices through rotation.

3. The method of calculating the two-dimensional flow field of a vertical axis wind turbine according to claim 1, characterized in that, The two-dimensional flow field comprises a velocity distribution and a pressure distribution. S2 specifically comprises: S201: setting a time step according to the rotation angle of the wind wheel of the vertical axis wind turbine; S202: determining the two-dimensional flow field of the vertical axis wind turbine at the current time by iterative calculation according to the time step.

4. The method for calculating the two-dimensional flow field of a vertical axis wind turbine according to claim 1, characterized in that, S3 specifically comprises: S301: calculating the relative flow velocity and the attack angle of the blade according to the position of the blade and the fluid flow velocity; S302: extracting the surface pressure of the blade according to the pressure distribution, and integrating the surface pressure; S303: calculating the blade lift according to the relative flow velocity, the attack angle, and the integrated surface pressure.

5. The method for calculating the two-dimensional flow field of a vertical axis wind turbine according to claim 1, characterized in that, S4 specifically comprises: S401: generating a target tip vortex element at the tip; S402: calculating the strength of the target tip vortex element by Joukowski's theorem according to the blade lift.

6. The method of calculating the two-dimensional flow field of a vertical axis wind turbine according to claim 1, characterized in that, In S6, the induced velocity comprises a normal induced velocity, a lateral induced velocity, and a longitudinal induced velocity.

7. The method for calculating the two-dimensional flow field of a vertical axis wind turbine according to claim 6, characterized in that, S6 specifically comprises: calculating the induced velocity by the Biot-Savart law formula.

8. The method for calculating the two-dimensional flow field of a vertical axis wind turbine according to claim 6, characterized in that, The normal induced velocity specifically comprises a first normal induced velocity, a second normal induced velocity, a third normal induced velocity, and a fourth normal induced velocity; The lateral induced velocity specifically comprises a first lateral induced velocity, a second lateral induced velocity, a third lateral induced velocity, and a fourth lateral induced velocity; The longitudinal induced velocity specifically comprises a first longitudinal induced velocity, a second longitudinal induced velocity, a third longitudinal induced velocity, and a fourth normal induced velocity.

9. The method for calculating the two-dimensional flow field of a vertical axis wind turbine according to claim 1, characterized in that, The mass source term specifically comprises: where S M represents the mass source term, p represents the fluid density, and h represents the distance from the induction point to the mid-average. The momentum source term specifically comprises: where f x and f y denote the transverse and longitudinal momentum source terms, and denote the transverse and longitudinal accelerations, u x denotes the flow velocity of the fluid in the x-direction, u y denotes the flow velocity of the fluid in the y-direction, denotes the partial derivative operator.

10. A two-dimensional flow field calculation system for a vertical axis wind turbine, characterized by A processor and a memory; The memory stores programs or instructions executable on the processor, and the programs or instructions are executed by the processor to implement the steps of the two-dimensional flow field calculation method of the vertical axis wind turbine according to any one of claims 1 to 9. ​

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