Wind driven generator blade capable of changing size of stress surface along with wind direction

Abstract

The invention relates to a blade of a wind driven generator. The size of a stress surface of the blade can be changed along with the wind direction. Blades belong to resistance type blades and do work by means of the thrust of wind, when the rotating direction of the blades is consistent with the wind direction, namely when the wind follows the wind, the blades are unfolded, the stress area of the blades is the largest, at the moment, the thrust of the wind does work, and the blades can receive the largest wind energy; when the rotating direction of the blades is opposite to the wind direction, namely against the wind, the thrust of the wind becomes resistance, the blades are contracted or folded at the moment, the stress area of the blades is reduced, and the resistance borne by the blades is minimum. By the adoption of the wind driven generator, due to the change of the stress area of the blades, the blades can receive wind energy to the maximum extent, the wind energy conversion rate is high, and the single-machine power of the vertical shaft resistance type wind driven generator can be effectively improved.

Description

TECHNICAL FIELD

[0001] Wind power generation, wind turbine blade technology. BACKGROUND

[0002] The existing mainstream wind turbine models are divided into horizontal axis wind turbines and vertical axis wind turbines.

[0003] The horizontal axis wind turbine uses airfoil blades to generate lift to drive the wind wheel to rotate, and converts wind energy into mechanical energy, which is the mainstream way of large-scale wind turbines at present.

[0004] The vertical axis wind turbine is divided into: Resistance type: rely on the thrust of the wind to do work, low efficiency (about 15%), suitable for micro scenarios (<10kW).

[0005] Lift type: rely on airfoil lift to drive, higher efficiency (about 30%), but high starting wind speed, mostly used in distributed or low wind speed areas.

[0006] Drawbacks of existing technologies Bottleneck of horizontal axis wind turbine: large blade transportation and installation difficulty, high operation and maintenance cost.

[0007] Limitations of vertical axis wind turbine: low wind energy conversion efficiency, limited single machine power, wind energy utilization coefficient (Cp value) is only 0.15, much lower than horizontal axis wind turbine, difficult to scale up, single machine capacity is below 100kW, low market share. SUMMARY

[0008] The present application is: a wind turbine blade, which can change the size of the force receiving surface with the wind direction. It is suitable for vertical axis wind turbine, and the blade is a resistance type blade that relies on the thrust of the wind to do work. When the rotation direction of the blade is consistent with the wind direction, i.e. downwind, the blade is unfolded, and the force receiving area of the blade is the largest. At this time, the thrust of the wind is doing work, and the blade can receive the maximum wind energy. When the rotation direction of the blade is opposite to the wind direction, i.e. upwind, the thrust of the wind becomes resistance, at this time the blade shrinks or folds, so that the force receiving area of the blade becomes smaller, and the resistance received by the blade becomes the smallest.

[0009] Take a vertical axis wind turbine as an example: the vertical axis wind turbine has four blades, and the blades are designed to rotate clockwise in one direction. When the wind direction is due east, the state of the blades at different positions is analyzed as follows: 1. When a blade is at the east face of the shaft, the blade is not under force, but the blade is about to turn to the south of the shaft to become a wind force receiving blade, and the blade gradually unfolds the entire force receiving surface at this time. 2. When the blade turns to the south of the rotation axis (the blade rotates from the east to the west, and the position is the south), the rotation direction of the blade is from the east to the west, which is consistent with the wind direction, that is, the blade is in the wind, and the largest area of the blade receives wind energy.

[0010] 3. When the blade turns to the west of the rotation axis, the blade is not forced at this time, but it will soon turn to the north of the rotation axis, that is, the wind force received by the forced surface of the blade will soon become resistance, at this time, the blade is gradually retracted or folded to minimize the forced surface of the blade.

[0011] 4. Then the blade turns to the north of the rotation axis (the blade rotates from the west to the east, and the position is the north), at this time, the rotation direction of the blade is from the west to the east, that is, it is opposite to the wind direction, that is, the blade is in the wind, at this time, the wind force received by the blade is the smallest.

[0012] 5. Then the blade turns to the east of the rotation axis again, and starts to rotate again, and the other blades are the same.

[0013] It should be noted that the unfolding, retraction and folding of the blade can be automatically performed due to the wind force, or can be performed by an intelligent system using external force.

[0014] In the present application, when the wind is too large, a part of the blade area can be reduced, that is, the mechanical device is used to prevent the complete unfolding of the blade, so that the wind turbine can operate stably.

[0015] Explanation of the meanings of some words in this application: Wind: the wind direction is consistent with the rotation direction of the blade, the wind thrust of the blade does work, that is, the rotation of the blade is pushed, and the power of the generator is provided; Wind: the wind direction is opposite to the rotation direction of the blade, the wind thrust of the blade becomes resistance, which hinders the rotation of the blade; The examples, wind direction and specific description of the size of the blade in this application are for the purpose of illustrating the present application, and cannot be used as the basis for limiting the claims of the present application.

[0016] Advantages of the present application The wind energy conversion rate of the wind turbine using the present application can reach 35 to 45 percent, which can effectively improve the single machine power of the vertical axis resistance type wind turbine.

[0017] The structure is simple, the manufacturing cost and operation difficulty are low, and it is very suitable for use in complex environments such as cities and roofs.

[0018] The main shaft of the fan is perpendicular to the ground, and no matter which direction the wind blows, the wind thrust can be used to push the blade to rotate.

[0019] The core components (such as generators, gearboxes) can be installed on the ground or near the ground, without the need for high towers and high-altitude installation.

[0020] The blade design is generally flat, which is difficult to process and convenient to maintain later.

[0021] The blades are installed symmetrically, and the structure is stable and not prone to tipping.

[0022] Low wind speed starting performance is good, and it is suitable for complex environment. It relies on the thrust of the wind to work, rather than lift, and can start rotating at low wind speed, and can utilize more wind resources.

[0023] In summary, it has strong adaptability, can be used at high wind speed and low wind speed, can meet the centralized power generation needs of large wind farms, and can also be applied to distributed small power scenarios.

[0024] The vertical axis wind turbine has many advantages in terms of structure, especially the resistance type blade. The design is simple, the structure is symmetrical, the transportation and installation difficulty is small, and the wind speed and direction adaptability is good. However, the only disadvantage is that the wind energy conversion rate is low. This leads to the fact that it has not become a mainstream wind turbine and is widely used.

[0025] The reason is that the traditional fixed blade has fixed blade positive and negative force area no matter how the blade shape is designed, although the shape is different, the wind resistance is different. However, the positive and negative wind resistance is not much different. The wind energy conversion rate is not high.

[0026] The present application changes the size of the blade area, so that the positive and negative force areas of the blade are different, so that the positive and negative wind resistance must increase. That is, if the characteristics of the present application are fully utilized, the positive wind resistance is maximized, and the negative wind resistance is almost 0, then the wind energy conversion rate must be maximized. DETAILED DESCRIPTION

[0027] 1. A vertical axis wind turbine is configured with 4 pieces of the blade of the present application.

[0028] The blade is 10 meters high and 5 meters long, and can start at a wind speed of 1 meter per second, and can work normally at a wind speed of 20 meters per second. The wind energy conversion rate is about 40% when working at a wind speed of 10 meters per second.

[0029] The power can be calculated at 5 wind speed (10 meters per second) to be: 12KW, and the daily power generation is: 288 degrees.

[0030] 2. A vertical axis wind turbine is configured with 4 pieces of the blade of the present application.

[0031] The blade is 50 meters high and 10 meters long. It can be started at a wind speed of 1 meter per second and can work normally at a wind speed of 20 meters per second. The wind energy conversion rate is about 40% at a wind speed of 10 meters per second.

[0032] At a wind speed of 10 meters per second (5-level wind), the power is 120 KW, and the daily power generation is 2880 degrees.

Claims

1. The wind turbine blade in the application can change the size of the force receiving surface with the wind direction. When the blade is in the same direction as the wind direction, the wind thrust does work, and the blade is expanded. At this time, the area of the blade is the largest.

2. The wind turbine blade in the application, when the blade is in the opposite direction of the wind direction, the wind thrust becomes resistance. At this time, the blade is contracted or folded, so that the force receiving area of the blade becomes smaller.

3. The wind turbine blade in the application, in the process of changing the size of the force receiving surface with the wind direction, the expansion or contraction of the blade can be automatically performed due to the wind force, or can be performed by using external force with the judgment of the intelligent system.