The francis turbine Steam turbines Turbine types The steam turbine on a page about engines? Maybe you wondered about it. It is hardly used in means of transport, but the steam turbine has many things in common with the combustion engine. The steam turbine changes chemically stored energy into mechanical energy, too. It's called a heat-force engine. The steam turbine works similarly to the water turbine, which is known probably by everyone. Not water, but steam is used as working medium. Turbine types When people began to use water power to win mechanical work, they looked first for the best forms of impellers. Three types were established thereby and variations of them are used today in various applications, among other in steam turbines in power stations, as marine propellers, as compressors in gas turbines etc. These three types are introduced here: The pelton turbine The pelton turbine (also free-jet turbine) was invented 1880 by L.A. Pelton. It possesses spoon-shaped shovels, the jet hits the impeller tangentially, gets divided by the two shovels and transfers an impulse. The pelton turbine is used in storage power stations with downward gradients up to 2000 meters and can contain up to 6 nozzles. Grafic: Pelton turbine enlarge (35 K, 770 * 905) Grafic: Pelton turbine, source: http://www- spof.gsfc.nasa.gov/stargaze/Spelton.htm The francis turbine he reaction turbine invented by J.B. Francis 1849 is hit by the jet almost axially (toward the axle) and radially (away from the center). The rotor blades can be adjusted, in order to ensure an even run. It looks similar to the type shown below as Steam turbine. The Kaplan turbine The Kaplan turbine, developed around 1915 by the Austrian V.Kaplan, looks like a marine propeller. The jet is led thereby axially on the freely adjustable shovel pages. Grafic: Kaplan turbine enlarge (35 K, 282 * 292) Besides the types described above, there are still other types of water turbines, e.g. the Bànki turbine, which are not closer described here. 1 http://www.mercubuana.ac.id

Coupling of several turbines Grafic: Coupled steam turbine. source: Helmut Hütten, "Motoren", Motorbuchverlag Stuttgart, S.379 In power stations today, different types of turbines are used in a series, e.g. one high pressure -, two medium- and four low pressure turbines. This coupling leads to an excellent efficiency (over 40%), which is even better than the efficiency of large diesel engines. This characteristic and the relatively favorable production make the steam turbine competitionless in power stations. Coupled with a generator and fired by an atomic reactor, they produce enormously much electric current. The strongest steam turbines achieve today performances of more than 1000 megawatts. 3 http://www.mercubuana.ac.id