Fundamentals of Jet Propulsion with Power Generation Applications

The purposes of the diffuser or inlet are first to bring air smoothly into the gas turbine. Second, for a propulsion diffuser to slow the fluid and to increase the pressure, or for a power generation inlet to increase the fluid speed and to decrease the pressure. And third, to deliver a uniform flow to the compressor. As indicated by studies for cycle analyses in Chapter 3, gas turbine performance improves with increasing pressure to the burner. The first component the air encounters is the diffuser or inlet, and the second component is the compressor. Thus, if the diffuser or inlet incurs a large total pressure loss, the total pressure into the burner will be reduced by the compressor total pressure ratio times this loss. For example, if 2 psia are lost in the diffuser or inlet, for a large engine this can result in 50 psia less in the burner.