A machine in which a fluid is used to produce rotational motion. The most widely used turbines are the steam turbines and water turbines that provide some 95% of the world’s electric power (in the form of turbogenerators) and the gas turbines that power all the world’s jet-propelled aircraft. In the impulse turbine a high-pressure low-velocity fluid is expanded through stationary nozzles, producing low-pressure high-velocity jets, which are directed onto the blades of a rotor. The rotor blades reduce the speed of the jets and thus convert some of the fluid’s kinetic energy into rotational kinetic energy of the rotor shaft. In the reaction turbine the discharge nozzles are themselves attached to the rotor. The acceleration of the fluid leaving the nozzles produces a force of reaction on the pipes, causing the rotor to move in the opposite direction to that of the fluid. Many turbines work on a combination of the impulse and reaction principles.
Turbine. Principle of the turbine.
A machine used to generate electricity by the expansion of a gas or vapour at high pressure through a set of blades attached to a rotor. The blades rotate as the result of the expansion and conversion of energy. Gas turbines and steam turbines are commonly used to generate electricity. A nozzle is used to direct the high-speed gas or steam over a row of turbine blades. The fluid pushes the blades forwards causing them to rotate due to the change in momentum. A row of stationary blades within the turbine redirects the fluid in the correct direction again before it passes through another set of nozzles and expands to a lower pressure. A steam turbine may have several pressure sections and operate at high pressure, medium pressure, and as the steam expands, a low-pressure section, all linked to the same shaft. The steam in the medium-pressure section may be returned to a boiler and reheated before doing further work, to prevent the formation of water in the turbine.
- Kármán
- Kármán vortex street
- Károlyi, Mihály, Count (1875–1955)
- Köhler, Georges J. F.
- Köhler, Wolfgang (1887–1967)
- Kölliker, Rudolph Albert von
- König eyepiece
- Königgrätz
- Königsberg bridge problem
- Königsberg bridges problem
- Königsberger ratio
- König’s paradox
- Köppen climate classification
- Köppen, Wladimir Peter
- Köppen, Wladimir Peter (1846–1940)
- Köprülü
- Kühne, Wilhelm Friedrich
- k‐simplex
- K–Ar method
- K–T boundary
- L
- L2TP
- label
- labelling
- labelling algorithm