DOC AIRBUS | AMM A320FHPT SHROUD AND STAGE 1 LPT NOZZLE ASSEMBLY - DESCRIPTION AND OPERATION
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
HPT Shroud and Stage 1 LPT Nozzle AssemblyA. HPT shroud and stage 1 LPT nozzle assembly
(1) The high pressure turbine (HPT) shroud and stage 1 low pressure turbine (LPT) nozzle assembly is located inside the aft end of the combustion case. It forms the interface between the core section and the LPT module of the engine. The forward flange of the assembly is rabbeted and bolted to the inner surfaces of the combustion case. The aft flange is bolted between the combustion case aft flange and the LPT stator forward flange.
(2) The shroud/nozzle support has a thermal response matched to the rotor to provide good tip clearance control and structural stability. An air cavity between the shroud/nozzle support and the combustion case directs mixed 5th and 9th stage compressor bleed air onto the support and the outer, or backside, of the shrouds. This cooling air maintains closer clearances between the shrouds and the rotor blades.
(3) The stage 1 LPT nozzles direct the core engine exhaust gas onto the stage one LPT blades. An air cavity between the stage one nozzle support and the combustion case directs 5th stage compressor bleed air through the nozzle vanes for cooling. After passing through the vanes, the air pressurizes and cools the cavity between the aft side of the HPT rotor and the forward side of the LPT rotor.
2. Description
A. HPT shroud and stage 1 LPT nozzle assembly
The HPT shroud and stage 1 LPT nozzle assembly consists of the shroud/nozzle support and HPT shrouds, and the stage 1 nozzles, inner air seal, and stationary air seal.
The HPT shroud and stage 1 LPT nozzle assembly consists of the shroud/nozzle support and HPT shrouds, and the stage 1 nozzles, inner air seal, and stationary air seal.
(1) The shroud/nozzle support forms the outer shell of the assembly and provides an air space or manifold area between the outer shell and the combustion case. High pressure compressor (HPC) bleed air is introduced into the manifold area to provide cooling for the HPT shrouds and the LPT nozzles.
(2) The HPT shrouds have a smooth abrasive rub surface that is tolerant to localized blade tip rubs and has good resistance to erosion from hot exhaust gases. The shrouds are held in place on the support by retainers and are individually replaceable.
(3) The assembly has 24 LPT nozzle segments, each having 4 vanes. The nozzle segments are installed in the shroud/nozzle support and are held in place on the nozzle inner air seal by the stationary air seal which is bolted on the aft face of the inner air seal. The assembly is bolted between the LPT case forward flange and the combustion case aft flange. Borescope ports at 5.30 and 8.30 o'clock positions (ALF) are provided in the support to allow inspection of the nozzle area.