Purely from the perspective of energy conversion, the wind wheel can be composed of any number of natural number blades. From the perspective of practical application, one blade has relatively high requirements on the transmission shaft, and it is difficult to ensure the balance of the wind turbine during operation. , and the loss of components is relatively large. 2-piece manufacturers have already used it, but it is still difficult to ensure the smooth operation of the equipment, while 3-piece greatly enhances the stability of the equipment during operation, and the wind energy utilization coefficient is relatively high, which belongs to more application categories. Relatively speaking, the force of more blades is not as stable as that of 3 blades, the installation and operation costs are higher, and the efficiency is less improved. It is only suitable for small landscape wind turbines.
Why do wind turbines have two blades instead of three or four or more? Isn’t this more convenient...
Generally, the power generation is between 10 kilowatts and Wind turbines below are called small wind turbines. Small wind turbines mainly consist of the following parts: wind wheel, generator, rotary body, speed regulating mechanism, direction regulating mechanism, braking mechanism and tower.
Classification of small wind turbines:
1. Classification by axis position
According to the position of the wind turbine shaft, wind turbines can be divided into horizontal axis wind power generation and vertical axis wind turbines.
(1) Horizontal axis wind turbine: The wind rotor of the horizontal axis wind turbine rotates around a horizontal axis. The rotor axis is parallel to the wind direction. The blades on the wind rotor are installed radially and are aligned with the rotation axis. Vertical and at an angle to the rotation plane of the wind wheel (called the installation angle). The number of wind rotor blades is 1 to 10 (mostly 3, 5, or 6). It has a high wind energy utilization rate when running at high speed, but requires a high wind speed when starting.
(2) Vertical axis wind turbine: The wind wheel of the vertical axis wind turbine rotates around a vertical axis, and the wind wheel axis is perpendicular to the wind direction. The advantage is that it can accept wind from any direction, so when the wind direction changes, there is no need to counter the wind.
2. Classification by power
According to the power of wind turbines, they can be divided into large, medium, small and micro wind turbines. Power However, with the breakthrough of single unit capacity, wind turbines of 1MW and above are gradually called medium and large wind turbines. Small wind turbines have a single capacity of several hundred kilowatts.
Why do wind turbines only have three blades? Isn’t the more blades the better?
1. The larger the area, the greater the resistance, and it is easy to be destroyed when a hurricane occurs. And the greater the resistance, the higher the energy loss.
2. The blade is one of the highest costs in the entire windmill, which can save costs.
3. Based on the blade length of 34 meters, when the wind is strong, the blade tip speed exceeds the speed of sound, causing some special air waves. I am not an expert so I cannot explain it more clearly.
4. It seems that the 120-degree angle is also good for stress.
With the development of the times, the functions of these machines and equipment have been continuously upgraded, such as grain grinding, water transportation, power generation, etc. Traditional wind turbines come in a variety of shapes and designs, but they are all currently being replaced by the same design. wind energy asClean renewable new energy has gained popularity in recent years. When you are walking near the wind turbine and admiring the sight of the wind leaves turning leisurely under the blue sky and white clouds, are you also curious about the difference between the 3 leaves and the 5 leaves of the wind turbine?
As a clean and renewable new energy, wind energy has received great attention in recent years. When you are walking near the wind turbine and admiring the sight of the wind leaves turning leisurely under the blue sky and white clouds, are you also curious about the difference between the 3 leaves and the 5 leaves of the wind turbine?
To put it simply, three leaves are easy to balance, but if there are too many leaves, it will be difficult to balance and the cost will be high.
At rated wind speed, the generated power is proportional to the swept area of the wind rotor, that is, a wind rotor with 200 blades and a wind rotor with 1 blade can produce the same power.
It can be seen from the above figure that as the number of blades increases, the wind energy utilization coefficient also increases, but in the process from 3 blades to 4 blades to 5 blades, the wind energy utilization coefficient increases by a large margin , compared with the increase from 1 leaf to 2 leaves to 3 leaves, the increase is much smaller. From a cost perspective, the gain outweighs the loss.
So, the fewer blades of a wind turbine, the better?
First of all, the advantage of multi-blade is the larger torque conversion rate, but in terms of energy conversion rate, the efficiency of 4-blade and 5-blade fans is lower than that of 3-blade fans.
The main reason is that the large resistance of multi-blade fans causes a considerable amount of turbulence that interferes with the rotation of the blades, thus reducing the energy conversion rate.
So it is much better to choose 3 leaves than 4 or 5 leaves. (Well, the same is true for electric fans); Secondly, too few blades will affect power generation efficiency.
In fact, there is currently a patent in Europe that has two leaves, placed vertically, which can double the efficiency! However, the 2-blade wheel hub has a special structure with a seesaw structure, and the fatigue problem is worse than that of the 3-blade wheel.
Moreover, the fewer blades, the higher the rated speed. When the speed is high to a certain extent, the circumferential linear speed of the blade tip is very large, causing large wind resistance. The drag torque limits the further increase in power generation power and speed. Therefore, it is not good to have too few blades. Three blades are mainly for good balance and low cost. After a long period of verification, they have become a common fan form today.