(4) Continuous Combustion. As discussed above, the fourstroke/cycle
pistontype engine performs four separate discrete events. Each event must be
completed before the next one begins. Basic gas turbine engine operation
consists of four events that are essentially the same as the pistontype
reciprocating engine; however, these events combine to form a continuous cycle.
As the gas turbine operates, each of the four events transpires continuously.
In the gas turbine engine, as long as there is a supply of air and fuel to
burn, expand, and maintain turbine speed, the cycle is said to be continuous
and selfsufficient.
(5) Thermal Comparison. The pistontype engine operates at relatively
cooler temperatures than the gas turbine engine. The piston engine withstands
combustion chamber temperatures of approximately 5000 degrees Fahrenheit (2760
degrees Celsius) for a short duration of time. The hot components are cooled
rapidly to maintain relatively low temperatures of only a few hundred degrees.
In the gas turbine, the combustion chamber maintains a constant temperature and
limits it to approximately 1000 to 2000 degrees Fahrenheit (537.7 to 1090.3
degrees Celsius). This is done to retain the resilience of internal components
and inhibit formation of foreign matter on rotating parts.
(6) Air Inlet Section. The air inlet section (Figure 119) serves to
furnish a uniform and steady airflow to the face of the compressor. Inlet
sections may be equipped with or without inlet guide vanes. Inlet guide vanes
serve to direct the air into the first stage of the compressor.
Figure 119. Air Inlet Section.
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OD0610
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