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Gas Turbine Working Principals
Gas turbine engines derive their power from burning fuel in a combustion chamber
and using the fast-flowing combustion gases to drive a turbine in much the same
way as the high-pressure steam drives a steam turbine. A simple gas turbine is
comprised of three main sections: a compressor, a combustor, and a power turbine.
The gas turbine operates on the principle of the Brayton cycle, where compressed
air is mixed with fuel and burned under constant pressure conditions. The resulting
hot gas is allowed to expand through a turbine to perform work.
7.1 Introduction
As the principle of the gas turbine, a working gas (air) is compressed by a
compressor and heated by combustion energy of the fuel at the first. The working
gas becomes the high temperature and high pressure. The engine converts the
energy of working gas into the rotating energy of the blades, making use of the
interaction between the gas and the blades.
As shown in the below figure, there are two types of gas turbine. One is the open
cycle type (internal type) and another is the closed cycle type (external type). Basic
components of both types are the air compressor, a combustor, and the turbine.
The gas turbine can handle a larger gas flow than that of the reciprocating
internal combustion engines, because it utilizes a continued combustion. Then the
gas turbine is suitable as the high power engine. The gas turbine for airplanes
(called a jet engine) makes use of this advantage.
As we said at the beginning of this chapter, the gas turbine operates on the
principle of the Brayton cycle and one variation of this basic cycle is the addition of
a regenerator. A gas turbine with a regenerator (heat exchanger) recaptures some of
the energy in the exhaust gas, preheating the air entering the combustor. This cycle
is typically used on low-pressure ratio turbines, and the resulting hot gas is allowed
to expand through a turbine to perform work. In a 33% efficient gas turbine, almost
© Springer International Publishing AG 2018
B. Zohuri, P. McDaniel, Combined Cycle Driven Efficiency for Next Generation
Nuclear Power Plants, https://doi.org/10.1007/978-3-319-70551-4_7
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