What are gas turbines?
A gas turbine, also called a combustion turbine, is a rotary engine that extracts energy from a flow of combustion gas. It has an upstream compressor coupled to a downstream turbine and a combustion chamber in between. Gas turbine may also refer to just the turbine element. Energy is released when air is mixed with fuel and ignited in the combustor. The resulting gases are directed over the turbine’s blades, spinning the turbine, and, cyclically, powering the compressor. Finally, the gases are passed through a nozzle, generating additional thrust by accelerating the hot exhaust gases by expansion back to atmospheric pressure. Energy is extracted in the form of shaft power, compressed air and thrust, in any combination, and used to power aircraft, trains, ships, electrical generators, and even tanks. Theory of operation Gas turbines are described thermodynamically by the Brayton cycle, in which air is compressed isentropically, combustion occurs at constant pressure, and expansion over
A gas turbine burns a gas or liquid fuel to produce rotary motion, the turbine blades spin about a central axis. The turbine and air compressor are mounted on a central shaft; the electric generator can be mounted on the same shaft or on a second shaft and driven by a gear drive. The rotary motion requires fewer moving parts than the reciprocating action of an IC engine and consequently produces fewer vibrations and needs less maintenance. Gas turbines were developed for marine engines in boats and jet engines in airplanes as well as in large industrial turbines for utility power generation. The smaller gas turbine generators are aeroderivatives, descendants of jet aircraft engines.
