7.4.
COMPRESSOR SECTION
The compressor assembly consists of the following: compressor front support, compressor
case, diffuser scroll, front diffuser, rear diffuser, rotor, rotor bearing, and oil seals. An exploded view of
the compressor assembly is shown in figure 7.3.
The compressor is a combination axial-centrifugal type with six stages of axial compression
and one stage of centrifugal compression. The rotor hub and blade assemblies and the impeller are
made from stainless steel. The compressor rotor front bearing (No. 1) is housed in the compressor front
support, and the compressor rotor rear (No. 2) bearing is housed in the compressor rear diffuser. The
No. 2 bearing is the thrust bearing for the compressor rotor assembly.
The compressor case assembly consists of upper and lower halves and is made of stainless
steel. Thermal-setting plastic is centrifugally cast to the inside surface of the case halves and vane outer
bands.
To achieve maximum compressor efficiency, a minimum clearance is necessary between the
compressor-blade tips and the case. The first time an engine is started, the blade tips cut their own tip
clearance in the plastic coating. The inside of the compressor must be kept free of dirt accumulation. A
dirty compressor can cause high turbine outlet temperatures, low engine power, and
191
Previous Page
