Steam Turbines

Essay by SimpleHigh School, 10th gradeA+, January 1997

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Steam Turbines

The invention of the water turbine was so successful that eventually, the idea came about

for extracting power from steam. Steam has one great advantage over water-it expands in

volume with tremendous velocity. To be the most effective, a steam turbine must run at a very

high speed. No wheel made can revolve at any speed approaching the velocity that a steam

turbine can. By utilizing the kinetic energy of steam flow, the turbine could achieve a higher

efficiency. As a result, the steam turbine has supplanted the reciprocating engine as a prime

mover in large electricity-generating plants and is also used as a means of jet propulsion.

The action of the steam turbine is based on the thermodynamic principle that when a vapor

is allowed to expand, its temperature drops. In turn, its internal energy is decreased. This

reduction in internal energy is transformed into mechanical energy in the form of an acceleration

of the particles of vapor.

The transformation that occurs, provides a large amount of available

work energy.

The essential parts of all steam turbines consist of nozzles or jets through which the steam

can flow and expand. Thus, the temperature drops, and kinetic energy is gained. In addition,

there are blades, on which high pressure steam is exerted. Stationary blades shift the steam onto

rotating blades, which provide power. Also, turbines are equipped with wheels or drums where

the blades are mounted. A shaft for these wheels or drums is also a basic component, as well as

an outer casing that confines the steam to the area of the turbine proper. In order to efficiently

use this contraption, it is necessary to have a number of stages. In each of these stages, a small

amount of thermal energy is converted to kinetic energy. If...