| Air Kite Wind Turbine |
The high-altitude wind is characterized by a large wind speed, the wind speed of 200m is about twice as high as 50m, and the wind speed of 400m is about twice as high as 100m. According to the wind energy in direct proportion to the cube of the wind speed, the wind energy of the same sweeping area is several times and dozens of times higher than the ground wind energy. Another feature of high-altitude wind is its wide distribution, high stability and constant year-round. Theoretical power generation time in many places can exceed 60%. Collecting high-altitude wind energy to generate wind power with high stability and low power generation cost is one of the remarkable features of high-altitude wind power, and one of the most significant advantages of high-altitude wind power compared to conventional wind power. The kite originated in China and has a history of more than 2,000 years. It is the world's first artificial aircraft. The invention of kites has profound implications for the development of science and technology. Kite has also been used in warfare, and aircraft have been born for nearly a hundred years. Now scientists have studied the application of kites to collect wind energy for high-altitude power generation. There are already many whimsy. The steel wire is used to rotate the ground device to rotate or oscillate, some is directly transmitted to the ground in the air, and some of them have been carried out. The experiment has achieved good results. This website believes that generating kites represented by Google X as air wind turbines is a promising method of generating air over the air. Here is a brief introduction to the working principle of Google X's power kite. Figure 1 is a photo on the internet. It looks like an airplane. It is actually an airplane. It has an organic wing, a vertical tail, a horizontal tail, a propeller, and a wing. There are also ailerons and flaps. |
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| Figure1—Google X air kite |
| Unlike the plane, the Google X aircraft is held by ropes, which are supported by the wind and the flowing air. Therefore, it is not an airplane. It is more suitable to call a kite. Figure 2 is the style of generating kites in the air (photo from the internet) |
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| Figure 2—Google X air kite as wind turbine |
| In order to facilitate the introduction of the structure and working principle of generating kites, the model of the kite is drawn with reference to these photos, as shown in figure 3. |
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| Figure3—main consist of air kite |
The kite with wing, generate lift under the action of the wind, allowing the kite to fly in the sky; flaps are installed at the trailing edge of the wing to regulate the lift of the wing; ailerons are also mounted at the trailing edge of the wing to be adjusted to produce different lifts on both sides of the wing; the flaps and ailerons are symmetrically mounted on the wings on both sides, the wings are mounted on the fuselage, and the rear wing is fitted with a vertical tail to change the direction of flight; a horizontal tail is also installed at the rear of the fuselage to regulate the flight up or down. Through the adjustment of the ailerons, vertical tails, and horizontal tails, the kite can roll up. There are also four wind turbines installed on the wing, and each generator has a rotor consisting of three blades on the front. The kite's traction rope wraps with a power cable that transmits the electricity from the kite wind turbine to the ground. |
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| Figure 4--Kite wind turbine in the sky |
The wind blows the kite in the sky, and the kite hangs in the air. The wind blows the rotors to drive the generator to rotate and emit electricity. The air speed is one to two times larger than the ground, and the same wind swept area can be several times to several tens of times higher than the ground. However, it is impossible for a kite to bring a large-sized rotor to the sky. A small rotor at a high altitude has no obvious advantage over a large wind rotor on the ground. The inventor of the kite wind turbine adopted a new mode of operation to get more power from the small kite wind turbine. They fly kites in the air, and their flight speed can be three to five times greater than the wind speed, so that the power generation of small wind turbines will increase by tens of times to one hundred or two hundred times. How to make kites fly, people who have let fly of kites have seen the phenomenon of kites tumbling in the air and winding around them. The speed of flying is much faster than the wind speed, which is caused by the fact that the kites are not adjusted and asymmetrical; and we just need kites to fight as a circle in the air, see figure 5 below. |
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| Figure 5-- Kite's circular flight |
| Through the animation, the kite wind turbine can be seen more clearly in the air. |
| Kite wind turbines do the animation of circular flight |
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When the kite takes off, the wind turbine blade is used as a propeller, the generator is used as a motor, the four propellers rotate at a high speed, and the kite takes off vertically. When the appropriate height and distance are reached, the kite regulates the flight angle and uses the wind to push into the circular flight. When flying in the circumference, the propeller rotates under the action of the wind, and the retracted kite also uses the propeller to make a vertical landing. The principle of circular flying on a kite is briefly analyzed in figure 6. There is a vector diagram on the top of figure 6, the arrow line u is the actual size and direction of the external wind speed; v is the forward speed of the kite, the v arrow line is the airflow speed felt by the kite movement, so it is opposite to the direction of motion; v and The speed W of synthesis V and U is the wind speed that the kite really feels, called the relative wind speed. This figure only shows the source of relative wind speed. The cross section of the wing in figure 6 is shown in orange-red, and the relative wind speed is w acting on the wing of the kite. The force on the wing is F (combination of lift and resistance), and the kite is pulled by the rope (in the figure The downward force), because the rope is very long, the kite in the picture can only be seen to do horizontal movement, the component of F in the horizontal direction is Ft, and the force Ft is the force that pushes the kite forward. Change your mind, the wing can be regarded as a blade of a large wind wheel; the kite makes a circular flight as the blade rotates-that is a circle rotates around the circumference of the circle, and its circumference diameter is several hundred meters, meanwhile, the sweeping area is shown in figure 7, the blue ring part on the left of figure shows that the kite is small, but neither is the swept area, on the contrary it can capture more wind energy. From the perspective of general wind turbines, the tip speed ratio is usually greater than 3, that is, the speed at which the kite makes a circular flight is more than three times faster than the wind speed, reaching the range from ten of meters to hundreds of meters per second. |
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| Figure6--force analysis of kite |
The length of ropes, diameter of circular flight area, height of altitude and power generation efficiency is controlled by computer according to theory and experience data, there are also various sensors and controllers on the kite to ensure the perfect flight. Kite can fly in the sky (single ring path) or horizontal "8" (double ring path), seeing figure 7. The circular flight is simple, but to solve the twisting problem of the traction rope, it is also necessary to ensure the normal transmission of electricity. The rope that crosses the "8" character will not be twisted. But due to the large flight width, a long rope is required. |
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