2) Nozzle vane leading edges are cooled by internal impingement air (10th-stage)
which enters through bosses in outer ends of vanes. This air is then used for
convection cooling of mid-chord region. A portion of air is discharged through holes
in the trailing edge while remainder of air is discharged through ports in the inner
end of vanes.
3) Turbine shrouds form a portion of outer aerodynamic flow path through turbine.
They are located axially in line with turbine blades and form a pressure seal to
prevent high pressure gas leakage or bypass at blade tip end. Sealing (rubbing)
surface of 1st-stage shrouds is cobalt Nicroly coating; 2nd-stage are Braddloy-filled
honeycomb. 1st-stage consists of 24 segments; 2nd-stage of 14 segments.
4) Interstage seal is composed of seven segments which bolt to inner flange at the
nozzle segments. Sealing surface consists of a honeycomb seal which mates with
rotating seal located between 1st and 2nd-stage rotor disks. Function of seal is to
minimize leakage of gases across 2nd-stage nozzle.
5) Impingement ring is located between stator support and 2nd-stage nozzle. It forms
inner diameter of cooling air manifold and directs 10th-stage compressor air into
nozzle vanes through ports.
6) Insulation jacket is made of sheet metal and thermal insulating material and is
located on outside of stator support. It prevents nacelle environment from interfering
with case temperature and also forms outer wall of circumferential cavity for
circulation of air for clearance control system.
7) Passive clearance control system is used to provide close tolerances, without rubs,
between turbine blades and shrouds.
a) High pressure turbine stator support design incorporates intermediate rings,
flange cooling air flows, and insulation jackets to produce a thermal expansion
characteristic that provides closer tip clearances and therefore greater turbine
efficiency.
b) Compressor discharge, and 10th-stage compressor air provide cooling flow to
isolate turbine support from rapid temperature changes.
(4) High Pressure Turbine Rotor
(a) High pressure turbine rotor is a 2nd-stage air cooled turbine. Turbine rotor consists of an
integral 1st-stage turbine disk/shaft, a conical vaned spacer with cover, a thermal shield,
and a 2nd-stage disk. Forward and aft rotating air seals are assembled to rotor shaft and
are used to provide air cooling cavities about rotor. An integral coupling nut and pressure
tube is used to seal and form internal cavity. Rotor disks and blades are cooled by a
continuous flow of compressor discharge air directed to internal cavity of rotor through
vanes which are part of forward pressure balance seal. Vaned spacer cover increases
pressure of the air discharged to 1st-stage blade dovetails which cools blade airfoils.
Remaining air is centrifuged through 2nd-stage blade dovetails and cools 2nd-stage
blade airfoils.
1) 1st-stage turbine disk/shaft combines rotor shaft and 1st-stage disk into a single
piece unit. Energy is transmitted to compressor through an internal spline at forward
end of disk/shaft. Sub-assemblies of disk/shaft are No. 4 and 5 bearing inner races
and locknuts, shaft thermal seal, diffuser, and forward air seal. 1st-stage blades fit in
dovetail slots in disk with seal dampers between blades. 1st-stage blade retainer is
bolted on forward face of the 1st-stage disk and incorporates two ring seals to
provide a seal air cavity about blades. Disk rim provides cavity passages for blade
cooling air to 1st-stage blades on aft side of disk.
767
AIRCRAFT MAINTENANCE MANUAL
CF6-80A SERIES ENGINES
72-50-00
NoC
Page 5
D633T1B7 Dec 22/2016
ECCN 9E991 BOEING PROPRIETARY - Copyright © Unpublished Work - See title page for details
EFFECTIVITY
ABX 001-007, 011, 012, 016-019, 021, 022, 025, 101,
109, 114, 115, 314-999
To Next Page
Loading...
