Turbine

(mechanical engineering) A fluid acceleration machine for generating rotary mechanical power from the energy in a stream of fluid.

A machine for generating rotary mechanical power from the energy in a stream of fluid. The energy, originally in the form of head or pressure energy, is converted to velocity energy by passing through a system of stationary and moving blades in the turbine. Changes in the magnitude and direction of the fluid velocity are made to cause tangential forces on the rotating blades, producing mechanical power via the turning rotor. Turbines effect the conversion of fluid to mechanical energy through the principles of impulse, reaction, or a mixture of the two (see illustration).

Turbine principles. (a) Impulse. (b) Reaction.

The fluids most commonly used in turbines are steam, hot air or combustion products, and water. Steam raised in fossil fuel-fired boilers or nuclear reactor systems is widely used in turbines for electrical power generation, ship propulsion, and mechanical drives. The combustion gas turbine has these applications in addition to important uses in aircraft propulsion. Water turbines are used for electrical power generation. See also Gas turbine; Hydraulic turbine; Impulse turbine; Reaction turbine; Steam turbine; Turbine propulsion; Turbojet.