DOC AIRBUS | AMM A320FLPT ROTOR/STATOR ASSEMBLY - DESCRIPTION AND OPERATION
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
Low Pressure Turbine Rotor/Stator AssemblyA. The low pressure turbine (LPT) module is a 4-stage axial-flow turbine.
It is mounted between the core engine and the turbine frame. The module consists of the following major assemblies :
It is mounted between the core engine and the turbine frame. The module consists of the following major assemblies :
(1) Stages 2-4 LPT nozzle assemblies (LPT stator assembly).
(2) LPT rotor assembly.
2. Description
A. LPT Stator Assembly
The LPT assembly consists of the LPT case assembly, stages 2-4 LPT nozzle assemblies and the air cooling tubes and manifolds assembly. The nozzle assemblies consist of cast vane segments, and are installed inside the LPT case.
The LPT assembly consists of the LPT case assembly, stages 2-4 LPT nozzle assemblies and the air cooling tubes and manifolds assembly. The nozzle assemblies consist of cast vane segments, and are installed inside the LPT case.
(1) The LPT case is made of nickel alloy. The case front flange is bolted to the stage 1 nozzle support ; the rear flange of the LPT case is bolted to the outer front flange of the turbine frame. The LPT shroud support is mounted radially in line with the front flange of LPT case and the stage 1 outer stationary air seal. Six thermal insulation blankets are attached to the inner surface of LPT case. Each blanket is divided into segments and is designed to accommodate either the nozzle segment vane outer platforms or the outer air seal segments. The outer air seal segments are radially in line with stages 2, 3 and 4 of the LPT rotor. At its periphery, and in the vertical plane of the stage 2 nozzle assembly, the LPT case has instrumentation ports at nine specific locations. Nine EGT (T495) thermocouples are installed in these instrumentation ports. Each of the thermocouple probes is engaged through one specific nozzle segment of the stage 2 nozzle assembly. The LPT case has three other ports located lengthwise, at the 5 o'clock position, aft looking forward. The three ports provide for the borescope inspection of the LPT internal ports.
(2) The stage 2 LPT nozzle assembly consists of 18 nickel alloy segments with aluminization. Each nozzle segment has 7 vane airfoils. The segment inner platforms are retained by the inner stationary air seals, which are the fixed part of the inner interstage rotating air seals. One of the nozzle segments has a port for borescope inspection at the 5 o'clock position (aft looking forward) and a hole to house one probe of exhaust gas temperature (EGT) harness. Eight other nozzle segments also have one hole to accommodate one probe of the EGT harness.
(3) The stage 3 LPT nozzle assembly consists of 20 nickel alloy segments of 6 vane airfoils each and is similar in design to the stage 2 nozzle assembly. One of the vane segments has a port for borescope inspection at the 5 o'clock position (aft looking FWD).
(4) The stage 4 LPT nozzle assembly consists of 22 nickel alloy segments of 6 vanes each and is similar in design to the stage 2 nozzle assembly.
One of the nozzle segments has a port for borescope inspection at the 5 o'clock position (aft looking FWD).
One of the nozzle segments has a port for borescope inspection at the 5 o'clock position (aft looking FWD).
(5) The LPT cooling system consists of 2 air cooling manifolds made of steel alloy and 2 tube halves made of steel alloy. Each manifold and tube half assembly is made up of 6 tubes provided with orifices which direct the air toward the LPT case.
(1) LPT disks are made of nickel alloy. The disk front flanges accommodate the blade retainer which provides axial retention of each blade stage assembly. They also retain the rotating air seals which control air passage between LPT nozzle assembly and rotor. The outer rim of disks has machined recesses accommodating the blade dovetails.
(2) The stage 1 blade assembly consists of 162 tip-shrouded, nickel alloy blades with aluminization, equipped with antiwear shields. The front of the blade dovetails has a retaining lug which houses a blade retainer.
Blade retainer is held axially by the rotating air seal.
Blade retainer is held axially by the rotating air seal.
(3) The rotating air seals are made of nickel alloy. They are sandwich-mounted between stages 1, 2, 3 and 4 disks. They control air passage between the stator and the rotor.
(4) Stages 2-4 of the LPT rotor are similar except for the following differences. Stages 2-3 LPT disks have 150 blades, equipped with antiwear shields, stage 4 LPT disk has 134 blades. The turbine rotor support is sandwich-mounted between the stage 3 rotating air seal and the stage 3 disk.
(5) The turbine rotor support, made of nickel alloy, provides connection between the assembly of disks and the LPT shaft. It divides the LPT rotor inner enclosure into 2 separate cavities.