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Water turbine

Water turbine
In the history of mankind, water engines have always played a special role. For centuries, various water machines have been the main source of energy in production. Then, the development of heat (and later electric) engines greatly narrowed the scope of their application. However, wherever there were cheap hydro (brook fast flowing waterfall or river rapids), the water engine could be preferable to all others, because it was very simple in its design, does not require fuel and had a relatively high efficiency. After the first half of the XIX century was invented by water turbine with very high efficiency, hydropower experienced as if reborn. Since the beginning of electrification worldwide unfolded construction of hydroelectric power stations, which receive their power generators driven by a powerful hydraulic turbines of various designs. And in our time, the share of hydro turbines accounts for a large portion of the world's electricity. Therefore, this is a great unit on the right is one of the greatest inventions.

Water turbines evolved from a water wheel, and before talking about its structure, we should say a few words about water wheels. As already mentioned, the first water wheels were used in ancient times. By design, they are divided into nizhneboynye (or undershot) and verhneboynye (or bulk).

Nizhneboynye wheels are the easiest type of water motor. They are not required for the construction of canals and dams, but at the same time had the lowest efficiency, since their work is based on a principle quite unfavorable. This principle was that leaking water under the wheels struck in the shoulder blades, causing them to rotate. Thus, only the force of the water pressure used in undershot wheels. A more rational in terms of energy are self-leveling wheel, which is still used and the weight of the falling water.

self-leveling wheel device was also very simple. On the rim of a large wheel or drum to attach a number of buckets. Water poured from the top of the chute into the top bucket. Bucket filled with water becomes heavier, he fell down and pulled over an entire rim. The wheel starts to spin. In place of the descending wheel becomes the next bucket. He, too, was filled with continuously flowing water and began to sink. In its place came a third, then a fourth, and so on. When the buckets reach the lowest point of the rim water are poured. Ceteris paribus verhneboynyh wheel power was higher than nizhneboynyh, but these wheels have a large size and low speed. In addition, for their effective work needed to create a significant drop of water, that is, to build canals, dams and other expensive facilities.

Any water wheel is placed on the shaft, which rotates with the wheel, and from there passed on to the rotation of the machine, which would lead to action. In antiquity and the Middle Ages, such motors are widely used in various industries, which use them to set in motion the hammers, bellows, pumps, weaving machines and other mechanisms.

It may seem that in the centuries-old history of the mechanics of waterwheels have learned about them. And that could come up in this new world as the old design? However, it turned out that it is possible. In 1750, the Hungarian Segner, who worked at the University of Göttingen, has put forward the idea of ​​a completely new engine water, which along with the pressure and the weight used is also the reaction force created by the flow of water.

Water flowed from the top to the vessel is connected with an axis which is located at the bottom of the tube cross-shaped curved ends in one direction. Water flowed through them, and receive at the same time the reaction force acts on all four tubes in the same direction, resulting in the rotation of the whole wheel. It was a very clever deal, has not received, however, this form of no practical use, but an action brought to his keen interest in some mathematicians and engineers.

The great German mathematician Euler was one of the first to respond to this new product, devoted to research Segner wheel some of his works. First of all, Euler pointed out the flaws in the design Segner, while noting that the low efficiency of the wheel was a consequence of unsustainable energy losses. Further, he wrote that these losses can be significantly reduced if the idea of ​​the new engine will get a more complete implementation. Significant losses occurred primarily when the water entering the wheel due to a sharp change of direction and water flow rate (the energy is spent on strike). But they can be reduced if the water supply to the wheel in the rotation direction at a speed of this rotation. At the exit there were also casualties, as part of the energy carried away with the water output rate. Ideally, water should be given to wheel all your speed. To do this, Euler proposed to replace the water-discharge tube horizontal curved tubes extending from the top down. Then there was no need to make holes for the release of water from the side, because you can just leave open the lower end of a closed tube. Euler predicted that in the future hydraulic machines of this new type (actually, it is talked about a hydraulic turbine, but most of the name was not yet in use) will have two parts: a fixed guiding unit, on passage through which water will flow into the lower swivel wheel, which is a working body of the machine. Despite the comments, Euler highly appreciated the invention Segner and perceptively pointed out that he opened a new path of development of the hydraulic motor, which is destined to a great future.

However, the Segner wheel and the work of Euler's more ahead of their time. The next seventy years, no one has tried to improve the Segner wheel in accordance with Euler's remarks. Interest in them in the first quarter of the XIX century, revived the work of French mathematician Poncelet, who offered a special kind of undershot wheels new design. Poncelet wheel efficiency reached 70%, which was completely inaccessible for other types of water motors. The secret of success lies in the fact that the wheels of the blades has been given a special semicircular shape, so that the supply water came to them in the direction of their curvature, passed some distance up the blade, and then, falling, access to the outdoors. Under these conditions, it was eliminated completely blow water on the blade at the entrance, which is usually lost a significant part of the energy of the water jet. The invention Poncelet was an important step on the way to a water turbine. To this way was passed through, missed the second element of the turbine described by Euler - guide vanes.

The first guide vanes to the water wheel applied Burdeau professor in 1827. He named his first car turbine (from the Latin turbo - fast rotation), then this definition came into use. In 1832, the first practical water turbine made applicable French engineer Furneyron.

Its turbine is consisted of two concentric, lying against each other wheels: inner, stationary the K, represents a guide vane, and the outer curved blades a, which was operating the turbine wheel. Water enters the turbine through the top tube covers the turbine shaft, and fell on the guide vane blades. These blades forced to move water along a curve line, causing it to flow into the horizontal direction in the turbine blade, without impact, over its inner circumference, the latter giving all its energy, and then uniformly flowed on its inner circumference. And re-enters the waste water never mixed with each other. The turbine wheel is firmly connected to the vertical shaft D, and by which motion was passed.

Furneyrona turbine efficiency reached 80%. design he created had tremendous significance for the subsequent history of turbine construction. Hearing about this amazing invention spread rapidly throughout Europe. Experts engineers from many countries for several years, came to a secluded spot of the Black Forest, to inspect the work there Furneyrona turbine as a great tourist attraction. Soon we began to build turbines worldwide.

Go to the turbines has become a revolution in the history of hydraulic motors. What was the advantage over their old water wheel? The above brief description of the turbine Furneyrona difficult to see Segner wheel. Meanwhile, it is based on the same principle of using water jet propulsion jets (why this type of turbines and jet received later the name). Just Furneyron carefully considered all comments and Euler used his own experience in hydraulic engineer. Turbine Furneyrona different from the waterwheel several important points. In the water the water wheel inputs and outputs in the same place. Because of this, both the speed and direction of movement of water in the blade wheels were different at different times - the wheel as it spends a hefty portion of its available capacity to overcome the constant stream of resistance. The turbine Furneyrona water from the guiding unit included one edge of the blade wheel, ran along the blade and dripped on the other side. As a result, the turbine water did not stop, did not change its direction of flow is reversed, and the input to the output edges flowed continuously. At each point of the blades it has the same speed in the direction and differ only in size. As a result, the turbine rotation speed theoretically depend only on the speed of the water, and therefore the turbine can rotate a few tens of times faster than conventional water wheel. Other favorable difference turbine was the fact that the water at the same time held all the blades wheel, and in the water wheel - only in a few. As a result, the energy of the water jet used in the turbine, is much better than in the water wheel, but its dimensions with the same capacity were several times less.

In subsequent years, it developed a few basic types of water turbines. Without going into details, we note that all of the turbine of the XIX century can be divided into two main types: reactive and jet. Jet turbine, as already mentioned, is an improved Segner wheel. She had a turbine wheel is fitted on the shaft with a specially curved blades. This wheel contains within itself or was surrounded by guide vanes. Last represented the stationary wheel with guide vanes. Water rushed down through the guide vanes and turbine wheel, the blades of the first channel water into the second blades. When pouring the water pressing on the blades and the rotating wheel. Rotation transmitted from the shaft on to which a device (such as an electric generator). Jet turbine proved to be very useful where the water pressure is low, but it is possible to create a difference of 10-15 meters. They got in the XX century, it is very widespread.

Another common type of jet turbines were. Their principal device is the fact that a jet of water at high pressure in the wheel struck the blades and this causes it to rotate. The similarity of jet turbine wheel nizhneboynym very large. Prototypes of such turbines have appeared in the Middle Ages, as can be inferred from some images of that time.

In 1884, an American engineer Pelton turbine jet greatly improved by creating a new impeller design. This smooth wheel blades former jet turbines were replaced by their special invention, having the form of two joined together spoons. Thus, the blade is not turned flat and concave, with a sharp edge in the middle. In this arrangement, the work of the water blade was almost entirely on the rotation of the wheel, and only a very small part of it was lost useless.

The water to the turbine Pelton came through a pipe leading from the dam or waterfall. Where the water was much thicker pipe was made and where the water is less than it was thinner. At the end of the tube I had a tip or nozzle, from which a strong water jet struggled. The jet fell into the spoon-shaped blades wheel, a sharp edge of the blade has cut it in half, the water pushed forward blades, and turbine wheel begins to spin. The waste water flows down into the discharge pipe. Wheel with blades and nozzle shroud of the top was covered by iron or iron. When a power Pelton wheel is rotated at high speed, making it up to 1000 revolutions per minute. It was convenient to where it was possible to create a strong water pressure. Pelton turbine efficiency was very high and was approaching 85%, and therefore it has received the widest dissemination.

After 80 years of XIX century electric current transmission system has been designed for long distances and have the opportunity to focus on the production of electricity "power plants" - power, a new era began in the history of turbine construction. In conjunction with an electric turbine has become the powerful tool with which man has put himself at the service of a great power hidden in the rivers and waterfalls.

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