Fan blade and wind driven generator

Abstract

The invention relates to the technical field of wind power generation equipment, in particular to a fan blade and a wind driven generator. The fan blade adopts the symmetrical wing type design, and has the remarkable aerodynamic performance advantage. Due to the symmetrical wing type, the fan blade can keep relatively uniform airflow distribution no matter which angle the fan blade is located in the rotating process, so that turbulent flow and resistance are reduced, and the wind energy conversion efficiency is improved. In addition, due to the design of the head and the tail of the symmetrical wing type, the fan blade is more balanced when being stressed, the structural stability of the fan blade is improved, and the service life of the fan blade is prolonged. The airfoil profile is optimized in real time through a curvilinear equation, the wind power condition of the current environment can be further matched, and it is ensured that the draught fan can keep the optimal operation state at different wind speeds.

Description

Technical Field

[0001] The present invention relates to the technical field of wind power generation equipment, in particular to a wind turbine blade and a wind power generator. Background Art

[0002] The working principle of a vertical axis wind turbine is to use the principle of aerodynamics to drive the generator to generate electricity through the impeller. Specifically, a vertical axis wind turbine is composed of a wind wheel, a generator, a controller and a battery. The impeller is composed of multiple fan blades, which are generally in the shape of an aircraft wing. The fan blades are fixed to the hub, and the hub is connected together by a connecting rod. When the wind blows through the impeller, the fan blades rotate under the action of the wind, thereby driving the generator to generate electricity.

[0003] In the design of wind turbines, the airfoil of the fan blades is one of the key factors, which directly affects the aerodynamic performance and power generation efficiency of the wind turbine. Traditional wind turbine fan blade airfoils usually adopt standard or standardized designs, which are usually based on experience or extensive industry practices and can be applied to most regions. However, for some regions, due to the unusual topography and climate of the region, the power generation efficiency generated by the use of standard or standardized types of fan blades is reduced, so it is necessary to optimize the airfoil of the fan blades in a targeted manner.

[0004] The commonly used optimization method is to simulate the existing wind turbine blades to obtain the most suitable wind turbine blades for individual regions. However, this method still selects from the original airfoils and still does not improve the old airfoils, which leads to the fact that the selected optimal airfoil does not improve the power generation efficiency much. At the same time, it is also impossible to effectively optimize the airfoil according to the actual situation, resulting in the inability to solve the problem of the mismatch between the airfoil and the current environment. Summary of the invention

[0005] In order to avoid and overcome the technical problems existing in the prior art, the present invention provides a fan blade and a wind turbine generator. The present invention can optimize the airfoil in real time through a curve equation, thereby better matching the optimized airfoil with the current environment.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A fan blade, wherein the airfoil of the fan blade is a symmetrical airfoil, the symmetrical airfoil comprising an upper bone line and a lower bone line directly connected at the head and connected to each other at the tail through a trailing edge; the upper bone line and the lower bone line are arranged axially symmetrically with a chord line as a symmetry axis, and the chord line intersects the midpoint of the trailing edge perpendicularly; the curve equation of the upper bone line is expressed as follows in the rectangular coordinate system O-XY:

[0008]

[0009] In the formula, the intersection of the upper bone line and the lower bone line is the origin O, the straight line where the chord is located is the X-axis, and the straight line passing through the origin O and perpendicular to the X-axis is the Y-axis;

[0010] y represents the ordinate of the upper bone line, in m; x represents the abscissa of the upper bone line, in m; a1, a2, b1, b2 and b3 all represent model parameters of the upper bone line.

[0011] As a further solution of the present invention: the value ranges of the model parameters are specifically: the value range of a1 is [-0.086, -0.08]; the value range of a2 is [0.086, 0.09]; the value range of b1 is [-1, -0.9]; the value range of b2 is [0.7, 0.8]; the value range of b3 is [0.05, 0.06].

[0012] A wind turbine generator adopts the above-mentioned wind turbine blade, comprising a tower that can stand on the ground, a generator connected to an electric power control system is fixedly installed on the top of the tower, a hub is transmission-mounted on the motor shaft of the generator, and a plurality of the wind turbine blades are mounted on the hub.

[0013] As a further solution of the present invention: each of the fan blades is evenly distributed on the outer circumferential surface of the hub in sequence around the circumference of the hub.

[0014] As a further solution of the present invention: the hub is fixedly mounted on the main shaft, the main shaft is rotatably mounted on the tower, and the main shaft and the motor shaft are matched through a gear set.

[0015] As a further solution of the present invention: the fan blades are made of glass fiber reinforced plastic composite materials or carbon fiber composite materials.

[0016] As a further solution of the present invention: an anemometer is installed on the top of the tower.

[0017] As a further solution of the present invention: a wind vane is installed on the top of the tower.

[0018] As a further solution of the present invention: a nacelle cover is installed on the top of the tower, and the generator is installed in the nacelle cover.

[0019] As a further solution of the present invention: the output shaft of the gear set and the motor shaft are connected to each other via a coupling.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The fan blades of the present application adopt a symmetrical airfoil design, which has significant aerodynamic performance advantages. The symmetrical airfoil allows the fan blades to maintain a relatively uniform airflow distribution at any angle during rotation, thereby reducing turbulence and resistance and improving wind energy conversion efficiency. In addition, the head and tail design of the symmetrical airfoil makes the fan blades more balanced when subjected to force, enhancing the structural stability and service life of the fan blades. By optimizing the airfoil in real time through the curve equation, it is possible to further match the wind conditions of the current environment and ensure that the fan can maintain the best operating state at different wind speeds.

[0022] 2. The precise range of model parameters ensures the flexibility and adaptability of airfoil design. By adjusting these parameters, it is possible to optimize the aerodynamic performance of wind turbine blades for different wind speeds, wind directions and terrain conditions. Parametric design not only improves the manufacturing accuracy of wind turbine blades, but also makes the performance of wind turbine blades more stable and reliable in different environments.

[0023] 3. The wind turbine of the present application uses optimized fan blades, which significantly improves power generation efficiency and stability. The optimized fan blades can better capture wind energy and convert it into electrical energy, thereby increasing the output power of the entire power generation system. In addition, since the aerodynamic performance of the fan blades has been improved, the operating noise and vibration of the generator have also been effectively controlled, improving the operating quality of the equipment.

[0024] 4. The uniform distribution of wind turbine blades ensures that the wind turbine can maintain balance and stability during rotation. This design reduces the additional stress and vibration caused by the uneven distribution of wind turbine blades and extends the service life of the generator. At the same time, the uniformly distributed wind turbine blades can also capture wind energy more effectively and improve power generation efficiency.

[0025] 5. The transmission ratio of the gear set can be adjusted according to actual conditions to ensure that the generator runs at the optimal speed. In addition, the connection between the main shaft and the motor shaft is also more stable and reliable, which improves the stability and durability of the entire system.

[0026] 6. Wind turbine blades made of fiberglass composite materials or carbon fiber composite materials have the advantages of high strength, light weight and corrosion resistance. These materials not only improve the load-bearing capacity of wind turbine blades, but also reduce the weight of wind turbine blades, making wind turbines more energy-efficient and efficient during operation. At the same time, these materials also have excellent fatigue resistance, extending the service life of wind turbine blades.

[0027] 7. The real-time monitoring function of the anemometer provides important data support for the operation of wind turbines. By monitoring wind speed changes, the operating status and output power of the generator can be adjusted in time to ensure that the generator operates under optimal conditions. This helps to improve power generation efficiency and reduce energy waste.

[0028] 8. The real-time monitoring function of the wind vane enables the wind turbine to accurately capture changes in wind direction and adjust the direction of the wind turbine blades as needed. This automatic adjustment function not only improves power generation efficiency, but also reduces additional stress and vibration caused by changes in wind direction. At the same time, the monitoring data of the wind vane can also provide important reference for the maintenance and management of wind turbines.

[0029] 9. The design of the nacelle provides effective protection for the generator. It not only prevents the harsh external environment from damaging the generator, but also reduces the spread of noise and vibration. In addition, the nacelle is convenient for maintenance and overhaul, improving the operational reliability and maintenance efficiency of the wind turbine.

[0030] 10. The use of the coupling makes the connection between the output shaft of the gear set and the motor shaft more stable and reliable. It can withstand large torque and axial force, ensuring that the generator remains stable when rotating at high speed. At the same time, the coupling also has certain buffering and shock absorption functions, which can reduce the additional stress caused by vibration and impact and extend the service life of the generator. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the structure of the fan blades of the fan in the present invention.

[0032] Figure 2 It is a structural schematic diagram of the wind turbine in the present invention.

[0033] Figure 3 It is a curve diagram of numerical simulation results of the angle of attack of the fan blades in the present invention.

[0034] Figure 4 It is a wind speed variation curve diagram in the present invention.

[0035] Figure 5 This is a comparison diagram of the fan blade airfoil before and after optimization in the present invention.

[0036] Figure 6 This is the pressure cloud diagram when the fan blade attack angle is 3° and the wind speed is 5m / s.

[0037] Figure 7 This is the pressure cloud diagram when the fan blade attack angle is 6° and the wind speed is 5m / s.

[0038] Figure 8 This is the velocity cloud diagram when the wind turbine blade attack angle is 3° and the wind speed is 5m / s.

[0039] Fig. 9 This is the velocity cloud diagram when the wind turbine blade attack angle is 6° and the wind speed is 5m / s.

[0040] Fig.10 This is a comparison diagram of the lift-to-drag ratio before and after optimization when the attack angle of the fan blade in the present invention is 3°.

[0041] Fig.11 This is a comparison diagram of the lift-to-drag ratio before and after optimization when the angle of attack of the fan blades in the present invention is 6°.

[0042] In the figure: 1. wind turbine blade; 11. upper frame line; 12. lower frame line; 13. trailing edge; 2. hub; 3. generator; 4. tower. DETAILED DESCRIPTION

[0043] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0044] See also Figure 1-2 In an embodiment of the present invention, a wind turbine generator includes a tower 4 that can stand on the ground, a nacelle cover is installed on the top of the tower 4, and a generator 3 is installed in the nacelle cover. The hub is fixedly installed on the main shaft, the main shaft is rotatably installed on the tower 4, and the main shaft and the motor shaft are matched through a gear set transmission. The output shaft of the gear set and the motor shaft are connected to each other through a coupling. Each of the wind turbine blades 1 is uniformly distributed on the outer circumferential surface of the hub 2 in sequence around the hub 2.

[0045] The generator 3 is connected to the power control system, which is the "brain" of the wind turbine and is responsible for monitoring the operating status of the wind turbine and adjusting the operating parameters of each component as needed. The control system usually includes a computer that continuously monitors the status of the wind turbine and controls components such as the yaw device and the brake device.

[0046] See also Figure 3 to Figure 11 , the optimization process of the symmetrical airfoil in this application is as follows:

[0047] 1. Obtain historical operation data.

[0048] The historical operation data of the fan blades include basic parameters of the fan blades, original airfoil data of the fan blades, and wind speed in the environment where the fan blades are located. This embodiment is for a small and medium-sized wind turbine with a rated power of 1 kW. The basic parameters of the fan blades of the wind turbine are shown in Table 1.

[0049] Table 1 Basic parameters

[0050]

[0051] The original airfoil data of the fan blade refers to the curvilinear coordinates formed by the original airfoil of the fan blade in the coordinate system O-XY.

[0052] 2. Build the model and determine the model parameters.

[0053] Construct an optimized airfoil upper bone line model, and the optimized airfoil upper bone line model is shown in formula (1):

[0054]

[0055] The bone line model on the optimized airfoil is a polynomial combination equation, with the starting point being the origin of the coordinate system and the end point being (0,1). By controlling a1, a2, b1, b2 and b3 in the equation, the bone line geometry can be adjusted. In this way, a standard symmetrical airfoil can be obtained. When using this standard symmetrical airfoil, it is only necessary to determine the airfoil chord length according to the design parameters of the wind turbine, such as power, speed, current, voltage, etc. After the chord length is determined, the wind turbine airfoil geometry that adapts to the design parameters can be obtained.

[0056] The curve coordinates in the original airfoil data of the fan blade are input into the optimized airfoil upper bone line model in turn, and a set of equations is established and solved; then the maximum and minimum values ​​of the same model parameter are obtained, and the value range of the model parameter is formed by the maximum and minimum values, and stored in the initial population for subsequent use of the genetic algorithm.

[0057] The value ranges of the model parameters of this embodiment are shown in Table 2.

[0058] Table 2 Model parameters

[0059]

[0060] 3. Determine the range of angle of attack.

[0061] Through the above basic parameters, the tip speed ratio λ = 3 can be obtained. The angle of attack of the fan blade is the sum of the relative speed and the chord line of the fan blade.

[0062]

[0063] Through the equation Derivative the leading edge angle θ of the fan blade, we get:

[0064]

[0065] Let formula (4) be 0, we can get:

[0066]

[0067] Substituting the tip speed ratio λ=3 into formula (5), we get θ≈109.47°. Substituting into formula (3), we get: Therefore, the fan blade attack angle should not exceed 19.47°.

[0068] Initially, the original airfoil was selected at a wind speed of 5m / s and numerical simulation was performed at different fan blade attack angles. The numerical simulation results are as follows: Figure 3 Observation Figure 3 When the blade attack angle of the wind turbine is 0°~6°, its lift-to-drag ratio is constantly increasing, and this range has the greatest impact on the efficiency of the wind turbine. When the blade attack angle of the wind turbine is 6°~10°, its lift-to-drag ratio shows a significant downward trend, and this range has no significant impact on the efficiency of the wind turbine. Therefore, we select As a reference angle of attack, the original wind turbine blade airfoil is numerically simulated under this angle of attack and combined with different wind speeds. When the lift-to-drag ratio and efficiency of the generator fan blades are greater, the weighting coefficients should not be evenly divided. The angle of attack weighting coefficients are C1 and C2 respectively. C1 and C2 can be determined according to formulas (6) and (7):

[0069]

[0070]

[0071] Among them, r1 is The corresponding lift-to-drag ratio. r2 is The corresponding lift-to-drag ratio.

[0072] 4. Calculate the bone line equation of the optimized airfoil under various conditions.

[0073] According to the area where the wind turbine is located, determine the annual wind speed change curve of the area and the wind speed change range, such as Figure 4 As shown in the figure, different wind speed weighting coefficients are set according to the actual local wind speed.

[0074] The ratio of the time occupied by different wind speeds to the time of one year is used as the wind speed weighting coefficient and is calculated using formula (7).

[0075]

[0076] The calculation results are shown in Table 3.

[0077] Table 3 Wind speed weighting coefficient

[0078]

[0079] The above article has conducted a preliminary investigation on the wind speed in this area. If the average wind speed is divided by day or hour, there may be some differences. Therefore, the wind speed range is conservatively selected to be 2 to 11 m / s. According to Table 3, the wind speed is divided into 2 m / s, 5 m / s, 8 m / s and 11 m / s, and the corresponding wind speed weighting coefficients are: D1, D2, D3 and D4. The value range of each wind speed weighting coefficient is as follows: 0.4 ≤ D1 ≤ 0.5; 0.2 ≤ D2 ≤ 0.5; 0.015 ≤ D3 ≤ 0.02; 0.005 ≤ D4 ≤ 0.01.

[0080] After determining the range of the wind turbine blade angle of attack and wind speed, a genetic algorithm is used to use the model parameters stored in the initial population, and then numerical simulation is used to simulate the lift coefficient and drag coefficient of each individual under different working conditions to obtain its lift-to-drag ratio. The fitness of each individual is obtained by the crossover operator verification method, and the multiple regression coefficient R 2 As the fitness function, the credibility of the obtained model is verified. Its definition is shown in formula (8):

[0081]

[0082] When R 2 >0.90, the model can be considered to have high credibility and can replace the simulation program for further multi-objective optimization. 2 When >0.90, the optimal coefficient combination under this working condition is obtained, that is, the upper bone line equation of the optimized airfoil under this working condition is obtained. The specific calculation results are as follows:

[0083] At the fan blade angle of attack hour:

[0084] Wind speed v = 2m / s, the optimal airfoil upper bone line equation is obtained as:

[0085]

[0086] Wind speed v = 5m / s, the optimal airfoil upper bone line equation is obtained:

[0087]

[0088] Wind speed v = 8m / s, the optimal airfoil upper bone line equation is obtained:

[0089]

[0090] Wind speed v = 11m / s, the optimal airfoil upper bone line equation is obtained:

[0091]

[0092] At Angle of Attack hour:

[0093] Wind speed v = 2m / s, the optimal airfoil upper bone line equation is obtained:

[0094]

[0095] Wind speed v = 5m / s, optimize the airfoil upper bone line equation:

[0096]

[0097] Wind speed v = 8m / s, optimize the airfoil upper bone line equation:

[0098]

[0099] Wind speed v = 11m / s, optimize the airfoil upper bone line equation:

[0100]

[0101] 5. Obtain the fan blade airfoil.

[0102] Each optimized airfoil bone line equation is segmented non-uniformly according to the standard airfoil, and several curve coordinate points are selected from the beginning to the end. For example, the first curve segmentation method is: (0, y 1,1 )、(0.05,y 1,2 )、(0.10,y 1,3 )、(0.15,y 1,4 )、(0.20,y 1,5 )、(0.25,y 1,6 )、(0.30,y 1,7 )、(0.40,y 1,8 )、(0.50,y 1,9 )、(0.60,y 1,10 )、(0.70,y 1,11 )、(0.75,y 1,12 )、(0.80,y 1,13 )、(0.85,y 1,14 )、(0.90,y 1,15 )、(0.95,y 1,16 ) and (1.00,y 1,17 ), a total of 17 curve coordinate points. The same goes for other curves.

[0103] Based on all the curve coordinates obtained above, the weighted ordinates corresponding to all the ordinates at the same abscissa value point are calculated respectively using the ordinate weighting formula shown in formula (9).

[0104]

[0105] Each horizontal coordinate value point and its corresponding weighted vertical coordinate are input into the optimized airfoil upper bone line model, and a system of equations is established and solved to obtain the specific values ​​of each model parameter. The values ​​are shown in Table 4.

[0106]

[0107] The specific values ​​of each model parameter are substituted into the optimized airfoil upper bone line model to obtain the optimized airfoil upper bone line equation as shown in formula (10).

[0108]

[0109] The optimized airfoil upper bone line equation is symmetrical along the chord line of the fan blade and connected to the trailing edge to obtain the optimized fan blade airfoil, as shown in Figure 5 shown.

[0110] The original airfoil data and the optimized airfoil upper bone line equation are input into the simulation software for finite element simulation, and the following is obtained: Figure 6-Figure 9 Finite element analysis results diagram. Figure 6 This is the pressure cloud diagram when the fan blade attack angle is 3° and the wind speed is 5m / s. Figure 7 This is the pressure cloud diagram when the fan blade attack angle is 6° and the wind speed is 5m / s. Figure 8 This is the velocity cloud diagram when the wind turbine blade attack angle is 3° and the wind speed is 5m / s.

[0111] Fig. 9 This is the velocity cloud diagram when the wind turbine blade attack angle is 6° and the wind speed is 5m / s. Figure 6-Figure 9 The right picture in the figure is the simulation result diagram corresponding to the optimized solution, and the left picture is the simulation structure diagram corresponding to the original solution.

[0112] right Figure 6 and Figure 7 From the pressure cloud diagram, it can be seen that at different angles of attack and wind speeds, the optimized solution has more low-pressure areas on the lower surface than the original solution, and more high-pressure areas on the upper surface than the original solution. Therefore, the pressure difference between the upper and lower surfaces of the optimized solution is higher than that of the original solution, which can provide more lift (taking the negative direction of the Y axis as positive). At the same time, the size of the high-pressure area at the leading edge of the optimized solution is not significantly different from that of the original solution, that is, the pressure difference drag does not change much. Therefore, the lift-to-drag ratio of the optimized solution will be significantly improved compared with the original airfoil.

[0113] right Figure 8 and Fig. 9 From the velocity cloud diagram, we can see that the high-speed area on the upper surface of the original solution is larger than that of the optimized solution. According to the Bernoulli principle, the average pressure on the upper surface of the optimized solution is higher than that of the original solution. This is consistent with what is shown in the pressure cloud diagram.

[0114] Integrate the simulation data and draw Fig.10 and Fig.11 . And by Fig.10 and Fig.11 It can be seen that under different working conditions of the airfoil of the optimized scheme, the lift-to-drag ratio is significantly improved compared with the original scheme.

[0115] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A fan blade, characterized in that: The airfoil of the fan blade (1) is a symmetrical airfoil, comprising an upper bone line (11) and a lower bone line (12) which are directly connected at the head and connected to each other at the tail through a trailing edge (13); the upper bone line (11) and the lower bone line (12) are arranged axially symmetrically with the chord line as the symmetry axis, and the chord line intersects the midpoint of the trailing edge (13) perpendicularly; the upper bone line model is expressed in the rectangular coordinate system O-XY as follows: In the formula, the intersection of the upper bone line (11) and the lower bone line (12) is the origin O, the straight line where the chord is located is the X-axis, and the straight line passing through the origin O and perpendicular to the X-axis is the Y-axis; y represents the ordinate of the upper bone line (11), and the unit is m; x represents the abscissa of the upper bone line (11), and the unit is m; a1, a2, b1, b2 and b3 all represent model parameters of the upper bone line (11).

2. A fan blade according to claim 1, characterized in that: The specific value ranges of the model parameters are: the value range of a1 is [-0.086, -0.08]; the value range of a2 is [0.086, 0.09]; the value range of b1 is [-1, -0.9]; the value range of b2 is [0.7, 0.8]; the value range of b3 is [0.05, 0.06].

3. A wind turbine generator, which uses a wind turbine blade as claimed in claim 1 or 2, characterized in that: The invention comprises a tower (4) which can stand on the ground, a generator (3) which is connected to an electric power control system is fixedly installed on the top of the tower (4), a hub (2) is transmission-mounted on the motor shaft of the generator (3), and a plurality of wind turbine blades (1) are mounted on the hub.

4. A wind turbine according to claim 3, characterized in that: The fan blades (1) are uniformly distributed in sequence on the outer circumferential surface of the hub (2) in the circumferential direction of the hub (2).

5. A wind turbine according to claim 4, characterized in that: The wheel hub is fixedly mounted on the main shaft, the main shaft is rotatably mounted on the tower (4), and the main shaft and the motor shaft are matched through a gear set transmission.

6. A wind turbine according to claim 5, characterized in that: The fan blade (1) is made of a glass fiber reinforced plastic composite material or a carbon fiber composite material.

7. A wind turbine according to claim 6, characterized in that: An anemometer is installed on the top of the tower (4).

8. A wind turbine according to claim 7, characterized in that: A wind vane is installed on the top of the tower (4).

9. A wind turbine according to claim 8, characterized in that: A nacelle cover is installed on the top of the tower (4), and the generator (3) is installed in the nacelle cover.

10. A wind turbine according to claim 9, characterized in that: The output shaft of the gear set and the motor shaft are connected to each other via a coupling.

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