secondary passages of each nozzle prevent foreign matter from clogging the orifices. A fuel drain valve,
at the bottom of the combustion case, automatically drains the combustion section after engine
shutdown in the event of a false or aborted start.
8.5.
GAS PRODUCER TURBINE SECTION
The gas producer turbine rotor assembly, illustrated in figure 8.9, consists of the turbine shaft
and the first and second stage disks and blades. The turbine disks are attached to the turbine shaft hub
with bolts and are separated from each other by
the turbine rotor inner seal. The first and second
stage turbine blades are shrouded. The shrouds
form a continuous band which tends to reduce
blade
vibration,
improve
the
airflow
characteristics, and increase the efficiency of the
turbine. The first and second stage turbine blades
are placed in the fir-tree serrations of the disks
and are held in place with rivets.
Figure 8.9. Gas Producer Turbine Rotor.
The turbine rotor is supported by the No. 3 bearing and by the splined end of the compressor
rear hub. Installed on the turbine shaft is the No. 3 bearing seal assembly.
8.6.
POWER TURBINE SECTION
The free-power turbine is a two-stage axial-flow turbine. The turbine inlet case, item 25,
figure 8.2, is mounted on the rear flange of the gas producer turbine case. The power-turbine rotor turns
counterclockwise while the gas producer rotor turns clockwise. The power turbine rotor assembly, items
16 and 18 in figure 8.2, consists of the turbine shaft, first and second stage disk and blades, turbine
coupling, and accessory drive gear. Tiebolts attach the disk and blade assemblies to the front end of the
turbine shaft. The shaft is supported at the rear by the No. 5 bearing and at the forward end by the No.
4 bearing.
The free-turbine inlet case houses the turbine inlet duct, the first and second stage vanes, and
the free-stage turbine rotor.
The free-turbine case, item 24, figure 8.2, is mounted to the rear flange of the free turbine
inlet case. The turbine case consists
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