Why three blades?

As the "originator" of wind turbines, windmills played a huge role in drainage in the Netherlands and became world-famous. The image of the four-bladed Dutch windmill is also deeply rooted in people's hearts.

Four-blade or even multi-blade windmills have already taken shape. Why did the wind turbine become a three-blade windmill?

The number of blades will not directly affect the energy utilization. On the contrary, too many blades will interfere with the air flow and reduce the utilization of wind energy. Wind energy utilization equipment can only capture and utilize up to 59.3% of the kinetic energy in the wind. In this way, a wind turbine can generate the same amount of electricity even with only one blade.

However, single-blade wind turbines have not become mainstream. A single blade will cause the wind wheel to be extremely unbalanced, seriously threatening the safety of the entire wind turbine.

Two symmetrical blades can improve this unbalanced force situation, but they are still not stable enough. Until more ideal load control technology emerges, the application of two-blade wind turbines will still be limited.

The three-blade wind turbine solves the problem of balance due to its optimal layout, but its "heavy" has also become one of the "pain points". A single wind turbine blade weighs 20 tons, and the wind wheel composed of three blades weighs more than 60 tons. It is really a heavy thing. Once there is a quality problem with the foundation on the ground, the entire unit may overturn and collapse.

Some manufacturers break the wind turbine into parts and use multiple small blades to transform it into four heads and twelve arms. 

No blades, but still electricity

The mad scientist was not willing to accept mediocre blades, so he came up with the "no blades" solution. The legendary electrical giant Nikola Tesla once applied for a patent for a bladeless turbine, but due to the lack of suitable manufacturing materials, it was ultimately unsuccessful.

Based on this idea, people developed a bladeless wind turbine with a volute shape. The wind rotates the inner disk, which drives the generator to generate electricity. However, this kind of "Peppa Pig"-like wind turbine needs to strictly ensure the processing and manufacturing accuracy of each component, and at the same time requires the wind to be aligned with the air inlet. Such harsh conditions restrict its development.

In order to take advantage of the wind coming from all directions, people have developed bladeless wind turbines with an "inverted horn" shape. This wind turbine installed in Hengshui City can capture wind energy in all directions and make full use of the breeze. After the airflow enters the interior, the speed of the airflow is gradually increased with the slowly shrinking pipes along the way, and is finally pushed to the narrowest section. generator to generate electricity.

In addition to "cheating" the wind into their own bodies to generate electricity, some companies have gone a step further and returned to the simplest columnar structure, launching the "Ruyi Golden Cudgel" - Vortex Bladeless.

It utilizes the phenomenon of "Karman Vortex Street": when air flows through it, "vortices" are generated, inducing reciprocating vibrations in the columns. To put it simply, when the pillar is shaken, electricity is emitted. However, the efficiency of this model is extremely limited, and long-term vibration will aggravate the wear and tear of materials. It does not yet have commercial application value.

In 2016, the wind power bus station near the National Music Center of Iceland was put into operation. The strange-shaped vertical axis wind turbine above the bus booth provides power for lighting and electronic products. This unit can not only adapt to low wind speed environments (2 meters/second), but can also work normally in cold winds of hurricane level (more than 50 meters/second).

The axis of rotation of a vertical axis wind turbine is perpendicular to the direction of the air flow, and generally perpendicular to the ground plane. Traditional horizontal axis wind turbines need to face strong winds, while vertical axis wind turbines are open to wind from any direction and accept all winds.

The structural capacity of vertical axis generators is also greatly enhanced, allowing them to handle stronger wind levels. These characteristics make vertical axis generators come to life in the vast ocean.

Intriguing new wind turbine

"EWICON" designed by a Dutch architect is a static net. There are multiple horizontal insulating tubes placed in the outer net of a rectangular steel frame. Each insulating tube is densely arranged with nozzles, which generate electricity through electrodes. Electrical water mist, the wind blows the water mist to form an electric current, thereby generating electricity.

In the movie "Big Hero 6", there are many motorboat generators floating in the sky to provide power to the city. In fact, this technology has been implemented in real life. The average wind speed at high altitude is much greater than that at the surface, and the wind speed fluctuation is more stable. Many companies have set their sights on high-altitude wind power with huge potential value and created commercialized "motorboat generators".

In order to make the overall structure lighter, the "kite wind machine" came into being.

Although these "imaginative" wind turbines look beautiful, how to efficiently and stably transmit power is still a big problem, hindering larger-scale applications.

Today, mature three-blade wind turbine technology has been put into large-scale use, but scientists are still exploring new generators. The strange appearance is just a superficial phenomenon. Getting infinitely close to the limit of wind energy utilization is the eternal goal of wind energy research. These ultimate pursuits beneath the surface of art are exactly where the romance of scientists lies.

The shape of the blade cross-section is asymmetrical up and down, flow speed of wind is high when it passes