Most devices such as wind power or electric fans are three leaves, why?

In fact, there have also been one-blade and two-blade wind turbines. But the most common number of blades in modern wind turbines is three, the result of a compromise of various aspects and parameters in the design process. These aspects include, but are not limited to:

Aerodynamics, energy conversion efficiency, manufacturing and maintenance costs, system reliability, noise, aesthetics. From a simple analysis of technical parameters, a larger number of blades can: increase mechanical torque; Increase the output power; But a higher number of blades will at the same time:

reduce the maximum rotation speed; This results in heavier manufacturing costs and more complex and difficult maintenance. Therefore, motors with a high number of blades are more suitable for operation at low speeds, such as water pumps and motors for grinding grain.

Wind turbines expect the blades to rotate at a relatively higher speed, so that the generator located in the center of the blades (at the top of the tower) does not need to be large to meet the grid frequency requirements. In addition, the higher the altitude, the higher the wind speed, the higher the wind speed. Due to the high towers of the wind turbines, the blades are also long (40m-60m*).

There is a significant difference in wind speed between blades that rotate high and blades that rotate low. If the generator has only two blades, then when the blades rotate to one high and one low, their force is obviously not uniform, so a stronger and more stable tower needs to be designed to support the generator and the blades. The three-blade generator can alleviate this imbalance to a certain extent, so the operation is relatively smooth and smooth.

Smooth smoothness means less noise, less wear. In order to avoid this problem, it is necessary to adopt the method of real-time pitching. That is, every time it rotates, the pitch angle of the blade changes in real time to compensate for the inclination torque force, which is very complex to control and the efficiency will become low.

In addition to saving the cost of a blade and the cost of installation and construction, the other gains outweigh the losses. <>

In short, it is the single-blade type: the single-blade type needs a higher speed to obtain the same amount of energy at the same size, which means more noise, more visual pollution, and more ecological impact; Unbalanced rotation requires counterweights, and the benefits of high rpm – lower ratio gearbox, lighter mass are weakened; Low efficiency. Therefore, there is no cost advantage.

Double-blade type: the pros and cons are similar to those of single-blade type; Three-blade type: it can achieve its own dynamic balance, low speed, low noise, and is not easy to be hit by birds.

More blades: low speed, high ratio gearbox is required, heavy, and brings trouble to manufacturing, installation, operation and maintenance; Easy to hit birds, oh no, it's bird hits. (The blades are relatively large in size, with a diameter of tens of meters.)

To sum up, the clover is the most suitable. <>

Wind power can still be roughly explained, first of all, we want to mention the concept of solidity. The solidity of the impeller refers to the proportion of the projected area of the wind turbine blades to the area of the wind turbine. Solidity can be changed by changing the number of blades of the impeller.

The solidity of the blades will affect the wind energy utilization coefficient. Wind energy utilization coefficient, also known as wind turbine axial work coefficient. It refers to the ratio of extractable wind energy to input wind energy, and if we want to generate electricity, we naturally want to obtain a high wind energy utilization coefficient.

Therefore, in general, three-blade or two-blade wind turbines are more suitable. As an aside, the wind turbine with high solidity has a relatively large torque, so if you look at the impeller of the mill in the past, it is rarely two or three blades. <>

The fan blades of the electric fan are in circular motion, the fan blades are not straight, they have a certain arc, so the blades are installed on the supporting disc also have a certain angle, from the perspective of cost performance, the three-blade electric fan is simple in structure and small in manufacturing difficulty, and the cost is relatively low, so this three-blade electric fan is also very common.

In addition, from the perspective of energy saving, the three-piece fan is also relatively energy-saving. Because the three fans can form an asymmetrical reasonable mechanical power, when one blade does not have the power potential energy, the other two are in the state of potential energy, and the two potential energy blades can naturally easily drive a blade that does not have potential energy temporarily, which can save electricity and energy.

From the point of view of aerodynamics, it is not that the more blades, the greater the wind, but to see whether the "arc" of the blade itself is scientific, and the ability of the blade to "bring the wind" will become larger, so it will increase the wind power with "twice the result with half the effort". Secondly, theoretically, the wider the blade, the greater the "wind" intensity. Therefore, it is not possible to judge the wind power of an electric fan simply from the number of blades.

This seems to involve knowledge of the functional loss of the motor, blade angle and rotational speed, blade symmetry, material strength, own weight, fluid velocity, etc. The more blades, the greater the resistance and the less the velocity. The wider the blade, the greater the resistance and the lower the velocity.

Electric fan: It should be to fan the blades to stand at all angles, the speed is generally required, the blades can not be too many, and the three pieces are more beautiful. And the turning point of the fan is moderate in speed and power.

: The blades are required to be light, and the power generated is large, so the blades are narrow, the number is small, the declination angle is small, but the speed is fast. And the turnaround of *** is speed-based.

CPU cooling fan: It requires strong air circulation pressure, so it uses many blades and large blade declination angles. And its turnaround is power-based.

Due to the fact that it involves the rotational speed to power ratio and the like (when the declination angle, number, and face width of the blades reach a value, the maximum work is done on the air. There are some technical things that don't be explained, but it's enough for the average person to know that.

One is because the triangle has stability;

second, because it is related to energy;

The third is because the three-bladed fan is called a three-blade fan, and there seems to be no theory that the number of blades of the fan will affect the effect of the wind (except for one blade, which does not conform to the principle of the electric fan) and too many blades will increase the cost of the product.

Summary. This is because wind turbines are the best way to improve the wind energy conversion efficiency of a wind turbine with three blades. To put it simply, three leaves are easy to balance, and more than three blades are difficult to balance and can lead to higher cost of the generator.

Due to the large resistance, the multi-blade fan will interfere with the rotation of the blades and reduce the energy conversion rate, so it is much better to choose 3 blades than 4 or 5 blades, like the electric fan used at home, in fact, this principle is also the same.

Why Wind Turbines Only Have Three Blades Why Are Wind Turbines Three-Bladed.

Although there are many types of wind turbines, they can be summarized into two categories: 1. Horizontal axis wind turbines, where the axis of rotation of the wind turbine is parallel to the wind direction; 2. Vertical axis wind turbine, the axis of rotation of the wind wheel is perpendicular to the ground or the direction of the air flow.

Why Wind Turbines Only Have Three Blades Why Are Wind Turbines Three-Bladed.

When the wind speed exceeds the limit speed of the fan, the fan will stop working. Because if the speed is too fast, the eccentricity is greatly enhanced, and the inertia tendency will break the balance of the fan itself, and the blades will easily break. Therefore, each model of fan has a maximum speed.

When the wind speed is too fast, it is necessary to operate the computer in the background to stop running the fan and reduce the damage caused by its own inertia.

Why mainstream wind power generation equipment uses three blades.

This is because wind turbines are the best way to improve the wind energy conversion efficiency of a wind turbine with three blades. To put it simply, three leaves are easy to balance, and more than three blades are difficult to balance and can lead to higher cost of the generator. Due to the large resistance, the multi-blade fan will interfere with the rotation of the blades and reduce the energy conversion rate, so it is much better to choose 3 blades than 4 or 5 blades, like the electric fan used at home, in fact, this principle is also the same.

Why does a wind turbine only have three blades Why is a wind turbine a three-blade Although there are many types of wind turbines, they can be summarized into two categories: 1. Horizontal axis wind turbines, where the axis of rotation of the wind turbine is parallel to the wind direction; 2. Vertical axis wind turbine, the axis of rotation of the wind wheel is perpendicular to the ground or the direction of the air flow. Why is the wind turbine only quietly missing three blades Why is the wind turbine three-bladed When the wind speed exceeds the limit speed of the wind turbine, the wind turbine will stop working.

Because if the speed is too fast, the eccentricity is greatly enhanced, and the inertia tendency will break the balance of the fan itself, and the blades will easily break. Early on, therefore, each type of fan has a maximum speed. When the wind speed is too fast, it is necessary to operate the computer in the background to stop running the fan and reduce the damage caused by its own inertia.

Destruction and wear and tear.

Hm: Isn't that the answer I searched<>

Dear, the principle is from the hospital.

It's the same. This input method,Hey.。

Although there is an air conditioner in summer, the fan is still very popular, I don't know if you find it, the fan usually has only 3 blades, although there are also five blades, but the family buys basically three blades, why not four or two? I've always had doubts, so let's take a look.

In fact, in addition to the reason of aesthetics, there are two other main reasons: one is the consideration of mechanics. The 3 fan blades are mechanically the most stable, not easy to deviate from the axis, and can also maintain a large air intake.

Another reason is to save energy. In the earliest days, there were fans with more than 3 blades. But later people found that 3 fan blades can form a reasonable power structure, which does not affect the effect of blowing cool breeze, and can greatly save energy and electricity, so the later electric fans are 3 fan blades.

In addition, the three blades have a good dynamic balance and are not easy to oscillate, thereby reducing the wear of the bearing. Extend service life and reduce maintenance costs.

Is it better to have a three-bladed or five-bladed electric fan?

Of course, the five blades are better than the three blades, after the fan changes from three blades to five blades, the blades become narrower, and to achieve the strength of the same stove, the steel plate is required to be thicker. In addition, the design of the leaf shape, the conversation friend is more complex than the original, with 50 tons of pressure stamping without forming, must be opened to 200 tons of pressure, the difficulty has increased a lot, ** is naturally high, the blade is relatively soft when it is windy.

There is little difference between the three-blade electric fan and the five-blade electric fan, the speed of the five-blade is slower than that of the three-blade, the noise will be slightly smaller, and the balance will be better (the jitter is smaller).

Under the same conditions, the more blades, the greater the resistance, the slower the speed, and the smaller the wind, the advantage is that the stability is good, and the fewer blades is the opposite.

Therefore, the best effect of the use of electric fans with specific blades is to be analyzed by browning.

Under normal circumstances, the blades of an electric fan are three. There are three main reasons:

First, the triangle has stability and is three-legged;

The second is related to energy, from a mechanical point of view. 3 fans can form an asymmetrical reasonable mechanical power, when 1 blade does not have the power potential energy, the other 2 are in the state of potential energy, 2 potential energy blades can naturally easily drive a blade that does not have potential energy temporarily, which can save electricity and energy.

Third, because the appearance of the three-bladed fan is more beautiful, the cost is also moderate, and too many blades will increase the cost of the product.

Considering the characteristics of rotation balance, the fan blades of the general electric fan are all odd-numbered blades, while the electric fan with even number of blades is easy to resonate when rotating, causing damage.

A large wind turbine weighs between 400 tons and 500 tons. The blades of a 6-megawatt wind turbine weigh about 70 tons, and the rotors of the generator weigh about 100 tons. The stator weight of the generator is about 140 tons.

In addition, the weight of the machine compartment and the weight of the tower are large, imitating the large Tanyo bureau of 460 tons.

The three-bladed type of wind power may be due to:

The angle between the three-bladed type is 120 degrees. The wind drives the three-blade generator to walk, begins to be parallel to a certain blade, drives it to rotate forward, and the effect of its driving is gradually obvious, after reaching a 60° angle with the blade, the direction of movement of the blade and the direction of wind movement gradually tend to be consistent, and the effect of wind force is gradually weakened. At this time, the angle between the wind and the next blade is 0 degrees (i.e., the wind is on the same parallel line as the next blade), and the wind will continue to act on the next blade.

If the three-blade type is changed to a four-blade type, the angle between the blades is 90°. When the wind is at a right angle of 90 degrees to one blade, the angle between the wind and the next blade is 0°. The wind is still working on the first blade, and it will be on the second blade.

If the wind is not the same at that time, for example, if the wind stops for a while, then it will cause one blade to push forward and the other blade to pause. In this way, it is not only not conducive to wind power generation, but also more depleting equipment.

The two-bladed blade is that the continuous force of the wind blowing cannot be continued, one goes forward, and the other blade is blown forward by the wind, resulting in the power generation device can not rotate well.

It can be summarized that the interaction between the four blades is relatively large, which affects the results of their joint action and reduces the efficiency. In the case of two blades, the blades contain each other, and the effect between them is also more obvious and undesirable.

It can be said that in the three-bladed wind power generation, there are two blades that play a derivative role (advantageous) and one blade that acts as a blocking function (the disadvantage, the blade that is lifted upwards). The shape of the wind turbine blades is not a straight plate type, but has a curvature, which is also the effect of letting the wind pass through in order to hold the wind at a favorable moment.

In this process, in terms of middle school physics knowledge, wind energy is converted into the kinetic energy of the blade and the potential energy of the blade, and the kinetic energy and potential energy of the blade are converted into electrical energy, regardless of friction. A wind force of 2 Newtons (2 Newtons of force is 2 Newtons of square meters) blows through a three-page generator, and the effect on one of its blades. Find how many joules it generates after it is from an angle of 0 degrees to an angle of 60 degrees with the wind.

The thought process should be given, the wind force is given, multiplied by the area of the blade is the force, please consider the angle, multiply by the sin or cos angle. The role here is to have a force arm problem, so it is simpler to consider, or the work is equal to f (force) multiplied by s (distance), with the wind acting on different points on the radius of the blade, the distance it travels is also different. As a result, the work done by the wind to push the blades around plus the work done by the potential energy of the blades in this process (the work done by gravity) is the work done to generate electricity.