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HISTORY OF TECHNOLOGY, TECHNOLOGY, OBJECTS AROUND US
Hydro turbine. History of invention and production
Directory / The history of technology, technology, objects around us Turbine - a rotary engine with a continuous working process and rotational movement of the working body (rotor), which converts kinetic energy and / or internal energy of the working fluid (steam, gas, water) into mechanical work. The jet of the working fluid acts on the blades fixed around the circumference of the rotor, and sets them in motion. It is used as a drive for an electric generator at thermal, nuclear and hydro power plants, as an integral part of drives for sea, land and air transport, as well as hydrodynamic transmission, hydraulic pumps.
In the history of mankind, water engines have always played a special role. For many centuries, various water machines have been the main source of energy in production. Then the development of thermal (and later electric) engines greatly narrowed the scope of their application. However, wherever cheap hydro resources were available (a fast-flowing stream, a waterfall or a rapid river), a water engine could be preferable to all others, since it was very simple in design, did not require fuel, and had a relatively high efficiency. After the very high efficiency water turbine was invented in the first half of the XNUMXth century, hydropower experienced a kind of rebirth. With the beginning of electrification, the construction of hydroelectric power stations began around the world, at which electric generators received their drive from powerful hydraulic turbines of various designs. And today, hydroturbines account for a large part of the world's electricity production. Therefore, this wonderful device is rightfully one of the greatest inventions. The water turbine developed from the water wheel, and before talking about its device, a few words should be said about water wheels. As already noted, the first water wheels began to be used in antiquity. By design, they were divided into bottom-hole (or gravy) and top-hole (or bulk). The bottom wheels were the simplest type of water engine. They did not require the construction of canals or dams for themselves, but at the same time they had the lowest efficiency, since their work was based on a rather disadvantageous principle. This principle was that the water flowing under the wheels hit the blades, causing them to rotate. Thus, only the force of water pressure was used in the pouring wheels. From an energy point of view, filling wheels were more rational, in which the weight of falling water was also used.
The filling wheel device was also very simple. A row of buckets was attached to the rim of a large wheel or drum. Water from the top of the gutter was poured into the upper ladle. The bucket filled with water became heavier, fell down and pulled the entire rim along with it. The wheel began to turn. The next bucket took the place of the lowering wheel. He, too, was filled with continuously flowing water and began to sink. In its place came the third, then the fourth, and so on. When the buckets reached the bottom of the rim, the water poured out of them. Ceteris paribus, the power of the upper-piercing wheels was higher than that of the lower-piercing ones, but these wheels had large dimensions and a low rotation speed. In addition, for their efficient operation, it was necessary to create a significant water drop, that is, to build canals, dams and other expensive structures.
Any water wheel was mounted on a shaft that rotated along with the wheel, and from it the rotation was transmitted further to the machine that they wanted to put into action. In antiquity and the Middle Ages, such engines were widely used in various industries, where they set in motion hammers, blower bellows, pumps, weaving machines and other mechanisms. It may seem that during the centuries-old history of the existence of water wheels, mechanics have learned everything about them. And what could be new in this old construction? However, it turned out that it was possible. In 1750, the Hungarian Segner, who worked at the University of Göttingen, put forward a completely new idea for a water engine, which, along with pressure and weight, also used the reaction force created by the flow of water.
Water came from above into a vessel connected to an axle, at the bottom of which there were cross-shaped tubes with ends bent to one side. Water flowed out through them, and the resulting reaction force acted in all four tubes in the same direction, setting the entire wheel in rotation. This was an extremely ingenious discovery, which, however, did not receive any practical application in this form, but aroused the liveliest interest of some mathematicians and engineers. The great German mathematician Euler was one of the first to respond to this novelty, devoting several of his works to the study of the Segner wheel. First of all, Euler pointed out the shortcomings in Segner's design, while noting that the low efficiency of the wheel was the result of irrational energy losses. He further wrote that these losses could be significantly reduced if the idea of a new engine were more fully implemented. Significant losses occurred, first of all, when water entered the wheel due to a sharp change in the direction and speed of the water flow (energy was spent here on impact). But they could be reduced if water was brought to the wheel in the direction of rotation at the speed of this rotation. There were also losses at the exit, since part of the energy was carried away with the exit velocity of the water. Ideally, the water should give the wheel its full speed. To do this, Euler proposed to replace the horizontal outlet tubes with curvilinear tubes going from top to bottom. Then there was no longer any need to make holes for the release of water from the side, since it was possible simply to leave the lower end of the closed tube open. Euler predicted that in the future hydraulic machines of this new type (in fact, it was a hydraulic turbine, but this name itself was not yet in use) would have two parts: a fixed guide vane, through which water would flow into the lower rotating wheel, which is the working body of the machine. Despite the remarks made, Euler highly appreciated Segner's invention and presciently pointed out that he opened a new path for the development of hydraulic engines, which was destined for a great future. However, both the Segner wheel and Euler's work were somewhat ahead of their time. For the next seventy years, no one tried to improve the Segner wheel in accordance with Euler's remarks. Interest in them in the first quarter of the 70th century was revived by the work of the French mathematician Poncelet, who proposed a special type of new-designed pouring wheels. The efficiency of the Poncelet wheel reached XNUMX%, which was completely unattainable for other types of water engines.
The secret of success was that the blades of the wheel were given a special semicircular shape, so that the supplied water entered them in the direction of their curvature, passed some distance up the blade, and then, descending, went out. Under such conditions, the impact of water on the blades at the entrance, on which a significant part of the energy of the water jet was usually lost, was completely eliminated. Poncelet's invention was an important step towards the water turbine. In order for this path to be completed to the end, the second element of the turbine, described by Euler, was missing - the guide vane. For the first time, Professor Burden applied a guide vane to a water wheel in 1827. He was the first to call his car a turbine (from the Latin turbo - fast rotation), after which this definition came into use. In 1832, the first practical hydraulic turbine was created by the French engineer Fourneuron.
His turbine consisted of two concentric wheels lying opposite each other: an internal, stationary K, which was a guide vane, and an external one with curved blades a, which was the working turbine wheel. Water entered the turbine from above through a pipe that wrapped around the turbine shaft and fell on the guide vanes. These blades forced the water to move along a curved line, as a result of which it flowed in a horizontal direction into the blades of the turbine wheel, without impact, along its entire inner circumference, giving the latter all its energy, and then flowed evenly along its inner circumference. The newly incoming and waste water never mixed with each other. The turbine wheel was firmly connected to the vertical shaft D, through which the movement was transmitted. The efficiency of the Furneuron turbine reached 80%. The design he created was of great importance for the subsequent history of turbine construction. Word of this amazing invention quickly spread throughout Europe. For several years, specialist engineers from many countries came to the remote place of the Black Forest to inspect the Furneuron turbine that worked there as a great attraction. Soon turbines were being built all over the world. The transition to turbines was a revolutionary change in the history of hydraulic engines. What was their advantage over the old water wheel? In the above brief description of the Furneuron turbine, it is difficult to see the Segner wheel. Meanwhile, it is based on the same principle of using the jet motion of a water jet (which is why this type of turbine was later called jet). It's just that Furneuron carefully considered all of Euler's remarks and used his own experience as a hydraulic engineer. The Furneuron turbine differed from the water wheel in several key points. In a water wheel, water entered and exited in the same place. Because of this, both the speed and direction of water movement in the wheel blade were different at different points in time - the wheel, as it were, expended a fair amount of its useful power to constantly overcome the resistance of the jet. In the Furneuron turbine, water from the guide apparatus entered one edge of the wheel blade, passed along the blade and flowed down from its other side. As a result, the water in the turbine did not stop, did not change the direction of its flow to the opposite, and flowed continuously from the inlet to the outlet edges. At each point of the blades, its speed was the same in direction and differed only in magnitude. As a result, the rotation speed of the turbine theoretically depended only on the speed of the water, and therefore the turbine could rotate several tens of times faster than a conventional water wheel. Another advantageous difference between the turbine was that the water simultaneously passed through all the blades of the wheel, and in the water wheel - only through some. As a result, the energy of the water jet was used in the turbine much more fully than in the water wheel, and its dimensions at the same power were several times smaller. In subsequent years, several main types of hydroturbines were developed. Without going into details here, we note that all the turbines of the XNUMXth century can be divided into two main types: jet and jet. The jet turbine, as already mentioned, was an improved Segner wheel. She had a turbine wheel mounted on a shaft, with specially curved blades.
This wheel contained within itself or was surrounded by a guide vane. The latter was a fixed wheel with guide vanes. Water rushed down through the guide apparatus and the turbine wheel, with the blades of the first directing water onto the blades of the second. When poured, the water pressed on the blades and rotated the wheel. From the shaft, the rotation was transmitted further to some device (for example, an electric generator). Jet turbines turned out to be very convenient where the water pressure is low, but it is possible to create a drop of 10-15 m. They became very widespread in the XNUMXth century. Jet turbines were another common type of turbine. Their fundamental device was that a jet of water under strong pressure hit the wheel blades and this made it rotate. The similarity of the jet turbine with the bottom wheel is very great. The prototypes of such turbines appeared in the Middle Ages, as can be inferred from some images of that time. In 1884, the American engineer Pelton significantly improved the jet turbine by creating a new impeller design. In this wheel, the smooth blades of the old jet turbine were replaced by special ones invented by him, having the form of two spoons connected together. Thus, the blades turned out to be not flat, but concave, with a sharp rib in the middle. With such an arrangement of the blades, the work of the water went almost entirely to the rotation of the wheel, and only a very small part of it was wasted uselessly.
Water to the Pelton turbine came through a pipe coming from a dam or waterfall. Where there was a lot of water, the pipe was made thick, and where there was less water, it was thinner. At the end of the pipe there was a tip, or nozzle, from which water escaped in a strong stream. The jet hit the spoon-shaped blades of the wheel, the sharp edge of the blade cut it in half, the water pushed the blades forward, and the turbine wheel began to rotate. Waste water flowed down into the outlet pipe. A wheel with blades and a nozzle was covered from above with a casing made of cast iron or iron. With strong pressure, the Pelton wheel rotated at great speed, making up to 1000 revolutions per minute. It was convenient where it was possible to create a strong pressure of water. The efficiency of the Pelton turbine was very high and approached 85%, which is why it was widely used. After a system for transmitting electric current over long distances was developed in the 80s of the XNUMXth century and it became possible to concentrate electricity production on "electricity factories" - power plants, a new era began in the history of turbine construction. In conjunction with an electric generator, the turbine became that powerful tool with which man put to his service the enormous power hidden in rivers and waterfalls. Author: Ryzhov K.V.
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