The Probert Encyclopaedia of Science & Technology

GAS-TURBINE

A gas-turbine is a form of engine in which a continuous stream of hot gases is directed against the blades of a turbine, causing it to turn. In most cases the gas, usually air, is first compressed in a compressor before passing into combustion chambers, where a portion of the gas is mixed with fuel and burned. The rest of the gas bypasses the combustion chamber and mixes with the hot gases emerging after combustion. This is then forced through nozzles to drive a turbine. Part of the power from this turbine is used to drive the compressor; the remaining power can be used in various ways, depending on the function of the engine: it may drive the propeller shaft of a turboprop aircraft or ship, the drive-shaft of a locomotive, or an electric generator. Alternatively, a turbine just big enough to drive the compressor can be used, and the remaining energy of the hot exhaust gases used to give a high-speed exhaust jet and hence a forward thrust; this is the jet engine. Gas-turbines are used in electricity generation for standby and peak-load service, in portable power plants, and in combined-cycle power generation. The high power-to-weight ratio of gas-turbines has led to their use in aeroplanes, and also in diesel locomotives and naval vessels.
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