Figure 1-15.--Large engine compressor rotor with midspan platforms.
rotor. Variable IGVs achieve the same purposes
positioned at various angles, depending on
as variable stator vanes (VSVs).
compressor speed, to ensure the proper angle of
Some GTEs have moveable, or variable,
attack of the air in the compressor blades.
stators. The position of the variable stators is
Varying the stator angle helps to maintain
determined by compressor inlet temperature (CIT)
maximum compressor efficiency over the operating
and engine power requirements. They are moved
speed range of the engine. This is important in
by mechanical linkages that are connected to,
variable-speed engines, such as those used for
and controlled by, the fuel-control governor.
main propulsion, Second, the variable stators
Variable stators have two purposes. First, they are
on large engines greatly reduce incidences of
1-15
