Chapter 1
Turbine Package System Overview
1-6
The HP compressor stator casing is in the form of an insert split along its horizontal centerline
and located in the pressure casing back plate. The HP compressor stator blades being retained by
dovetail grooves in the insert.
Center Casing and Bearing Housing Assembly
The Center Casing and Bearing Housing Assembly provide support for the hot end of the gas
generator assembly, including the combustion system and the Compressor Turbine (CT) Outer
Casing. A tilting pad journal bearing provides support for the exit end of the gas generator rotor.
Combustion System
The Combustion System comprises six tubular combustion chambers symmetrically positioned on
the forward face of the Center Casing and Bearing Housing Assembly.
The system is of axial reverse flow design; air leaving the compressor exit nozzle is reversed and
enters the head of the combustion chambers via a swirler plate, which imparts a rapid swirling
motion to the flow to ensure complete mixing of fuel and air.
Compressor Turbine Outer Casing
The CT Outer Casing provides the interface between the Center Casing and Bearing Housing
Assembly and the Power Turbine (PT) Outer Casing and Interduct Assembly. Provisions are
made, at the bottom of the casing, for the attachment of the rear gas generator support
assemblies. Boroscope access holes are provided in the top of the casing to enable examination
of the CT stator and rotor blades.
Compressor Turbine Nozzle Assembly Stage 1 and Duct
Within the Compressor Turbine Nozzle Assembly Stage 1 and Duct are housed the CT1 nozzle
segments, the combustion chamber transition ducts and the CT 2 nozzle assembly. Also, with the
CT2 nozzle segments is the CT 2 retaining shroud, which carries a seal ring between the CT
Nozzle Assembly Stage 1 and Duct and the PT Outer Casing and Interduct Assembly.
Turbine Rotor Assemblies
The turbine rotor assemblies are comprised of two separate assemblies, the CT Rotor Assembly,
and the PT Rotor Assembly.
The Compressor Rotor is a single spool 11 stage axial design made up of a series of discs
carrying dovetail rooted compressor blades, located together with Hirth couplings at the outside
diameter and held together with a single central tension stud bolt. Overhung from the
Compressor rotor and secured to it with a central tension stud bolt is the CT, which is of a two-
stage design. It consists of two rotor discs located on the Compressor spool by means of a
central tension stud and Hirth couplings and carrying fir tree rooted turbine blades.
The Power Turbine is of two-stage axial design, consisting of two-rotor disc located with Hirth
couplings and carrying fir tree rooted turbine blades. The PT rotor is bolted to a solid output
shaft by means of a tension bolt.
