The oldest water engines in human history were the wooden water wheel, that is a horizontal shaft, provided with vanes on its circumference. Even in antiquity the old Greeks and later the Romans were using it. The Roman architect and “engineer” Vitruvius, who lived in the 1st century B.C., made a description of such a wheel. From his chart we can see, that it was a wheel with lower drive. It means, that the water stream affected only a few lower vanes. The effectiveness of this water wheel was very low and so its output was around 0,37 kW (which corresponds with the output of a hand electric drill.

Schéma vodního kola podle Vitruvia.
Vlevo vlastní kolo, vpravo ozubený převod a nahoře mlýn.

Therefore in the 2nd century a wheel with upper drive started to be used mainly in hilly regions. This wheel used greater water descent. The wheel takes over the energy of falling water too. The maximal output of this water wheel was 2.000 kW (which corresponds with the output of a lathe). During the Middle Ages the output was growing up to incredible 37 kW and it allowed many mills, iron-mills and other crafts to gain their fame. The theoretical reasons of this wheel’s advantages wasn’t pronounced until the 18th century.

In spite of this a French military engineer Jean Victor Poncelet (1887 – 1867) invented a water wheel with lower drive, which reached the effectiveness of 70 %. How did he achieved it? Very simply: he replaced the straight vanes with bent ones! These wheels expanded then very quickly. But even this was not enough. And so another French “soldier” Claude Burdin (1790 – 1873) innovated this wheel and as the first man he used the name “turbine” (from Latin turbo – I turn). His pupil Benoit Fourneryon (1802 – 1867) won the first prize advertised by the French Academy of Sciences for the most effective water engine of the year 1832. His first turbine was designed for French ironworks and it reached for 60 turnings a minute at the output of 40 kW. Later he was building turbines, which were working at 2.300 turnings a minute, giving the output of 45 kW. The effectiveness of these turbines exceeded
80 %.

In defiance of the remarkable effectiveness, Fourneryon´s turbine had some imperfections. These problems were caused by the radial exit of water, which was passing through the turbine. And so an American engineer, of English origin, James Bicheno Francis (1815 – 92) constructed his own turbine. In fact he turned the original Fourneryon´s turbine inside out: he let the water to enter the rotation wheel from without through the wreath of vanes. The wheel was turning inside the ringlet of vanes. The water was getting out of the wheel in axial way. Francis´ turbine is a pressurized turbine, because the water enters the wheel under greater pressure, than under which it gets out of it.

Oběžné kolo francisovy turbíny o výkonu 1,42 MW
(z původní elektrárny na pražském ostrově Štvanice z let 1913 - 1914)

Thanks to the right curvature of vanes, which he found after creating a lot of models, his turbines reached greater effectiveness than the machines of his predecessors. However Europe was doggedly refusing these turbines, because nobody could prove their effectiveness with a calculation. First after a lot of innovations Francis´ turbines spread all over the world. The main innovation was done by a German professor R. Fink in 1878. He used revolving vanes, which allowed t0 regulate the quantity of water streaming through the rotation wheel.

Schéma Peltonovy turbíny.
Vlevo ostřikovací tryska s regulační jehlou.

In 1829 a son called Lester was born into a family of an American farmer in Ohio. After his study and a lot of life peripetia the young man Lester Allen Pelton came to Camptonville in Nevada, where the gold started to be exploited. Mines were using all achievements of that time. But the thoughtful Lester didn’t like the fact, that the mines used too much wood for the production of steam for their stream machines.. The surrounding woods were on the wane and the river Yuba was flowing here without any benefit. In 1878 he was experimenting with a few types of water wheels. They say, that he got the right idea when driving some cows back with a splash-hose. He should have pointed just at the cow’s nostrils: the stream of water was divided and was turned at 180° , then it came back over the outer side of the nostril. It is hard to say, whether this story was devised or whether it is truth. However one thing is certain, the vanes of Pelton´s turbine are double, just like two ladles next to each other and they return the stream of water back. So they use a great part of kinetic energy of the streaming water, which is brought from a high placed reservoir and which falls on the vanes through a controllable tangential nozzle (later even through a few nozzles). The effectiveness of these turbines is about 90 %. Because Pelton´s turbines use high descents (they reach even 1 km and their efflux is about 50 km/h), they have to be provided with such an apparatus, which can turn away the water jet if needed. (The water cannot be shut, because the strong dynamic push would break the conduit.)

Patnáctitunové oběžné kolo Peltonovy turbíny, které svými 13 680 kW do roku 1987
zásobovala 16 000 domácností v Nevada City
(picture from web page http://www.coolspots.com/spots/nev/page209601.html)

The effectiveness of the preceding turbines reaches 90 %, but only under the condition of an optimal water flow. When the flow sinks, the effectiveness sinks rapidly too. This was the main reason, why the professor of the Technical university in Brno Viktor Kaplan (1876 – 1934) started to adjust Francis´ turbine. He dilated the channels between the vanes. In the end he created a rotation wheel with the shape of a screw propeller with turning vanes. These vanes could change the angles of the streaming water – according to the changing water flow. So a high effectiveness could be reached even at a half flow. The patent proceedings happened in the year 1912 – 1913. The first turbine of this type started to work in 1918 in a spinning mill in Ulm – Austria. The first turbine of this kind was installed in the new Czechoslovak republic in Podebrady in 1921.

Schéma Kaplanovy turbíny.
Voda prochází radiálním rozváděcím kolem s natáčecími
lopatkami na axiální otočné kolo s 3 - 10 natáčecími lopatkami.

As usually, the inventor and his invention became the mark of criticism, even though the praxis confirmed their advantages. However Kaplan had to solve one serious problem: a “disease” which afflicted the flat vanes of the rotation wheels, so called cavitations. The underpressure caused, that the water on the lower part of the vanes was evaporating (boiling). The arose bubbles of steam and gas were wandering to the places of higher pressure, where they are destroyed in an implosion. This causes quite dangerous vibration and a heavy corrosion. The inventor’s health was damaged by this fight and practical problems, but in the end his turbine won.

Model Kaplanovy turbíny v Národním technickém muzeu v Praze.
Na rozdíl od expozice v NTM bývá většinou svislá.
(obr. převzat z "dobře utajené" stránky http://www.ntm.cz/ak-39.htm)

The development of the contemporary hydraulic turbines is divided into two groups. First the trend makes for greater descent and still greater units. Kaplan’s turbine are now used for descents up to 70 m (Orlicka dam 70,5 m). Francis´ turbines up to 610 m. The greatest descent in the world is used by Pelton´s turbine in Reisseck – Austria (1770 m). The greatest independent unit is in Itaipuu – Brazil, there are 18 Francis´ turbines with 700 MW (altogether 12.600 MW).

Obří hydroelektrárna  Itaipu v Brazílii na řece Parama
(picture from web page http://www.abb.com/global/abbzh/abbzh260.nsf?OpenDatabase&db=
/global/abbzh/ABBZH262.nsf&v=e&e=us&c=1545DF11BFE94889C1256833006CB3A4)

On the other hand the small water power station built in the 30´s are restored and other small ones are built. Even though their working is not as cheap as the operation of their great “colleagues” they still help to reduce the quantity of fossil fuel. The conservation of nature starts to be a sufficient reason.