DOC AIRBUS | AMM A320FCOMBUSTION CHAMBER AND HIGH PRESSURE TURBINE (HPT) 1ST STAGE NOZZLE - DESCRIPTION AND OPERATION
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
1. General
A. Combustion Chamber
(1) The diffuser case, combustion chamber and turbine nozzle supply the hot exhaust gases of internal combustion to the turbine modules. The diffuser also functions as a structural support for the High Pressure Compressor (HPC) and the High Pressure Turbine (HPT) cases.
(2) Compressed air flows from the exit of the HPC into the diffuser case and combustor section. During entry, the airflow is made straight while the contour of the inner diffuser case lets the air expand before it moves to the combustion chamber. Metered fuel is supplied to the combustion chamber through 18 fuel nozzles and the fuel and air mixture is burned inside the combustion chamber. The HPT 1st stage vanes point the high temperature and high velocity gases out of the combustion chamber to supply the turbines and make thrust at the exhaust nozzle.
2. Description of the Combustion Chamber and HPT 1st Stage Nozzle Module
Combustion Chamber and HPT 1st Stage Nozzle ModuleA. Technology for Advanced Low NOx (TALON) trade mark combustion chambers are designed for decreased emissions (NOx and smoke).
(1) The combustion chamber is a TALON X trade mark type combustion unit.
(2) The combustion chamber assembly contains an inner and outer liner and a hood and bulkhead at the front.
(3) The bulkhead has ports for the fuel nozzles and openings for HPC air.
(4) The inner and outer liners have combustion holes (which supply combustion air used to burn the fuel) and dilution holes (which mix the air and fuel correctly).
(5) This type of combustion chamber is a floatwall design.
(6) The inner and outer liners have cast segments that can be replaced and they have a thermal barrier layer.
(7) There are ports in the sides of the outer liner for igniter plugs which are used to start and continue fuel combustion.
(8) The combustion chamber mixes air and fuel and burns this mixture to expand the volume of gas.
(9) The gas then moves to the HPT 1st stage nozzle, which turns the gases through vanes at the correct angle to go into the HPT.
B. The 1st stage nozzle contains 32 vanes.
(1) The vanes are hollow and let the air that flows around the combustion chamber through the holes in the vane airfoils and across the airfoil surface.
(a) This air keeps the vane surfaces cooler.
(2) There is also a thermal barrier layer on the vanes to help stop heat damage.
(3) A 1st stage cooling air duct at the rear of the 1st stage nozzle collects cooling air from the diffuser area to use in the 1st stage vanes and in the 1st stage blades of the HPT.
(a) This cooling air duct, of the Tangential On-Board Injection (TOBI) type, supplies cooling air to the HPT 1st stage seal and hub at the correct angle for their contour.
(4) Seal surfaces at the rear of the duct assembly and mating knife edges on the HPT 1st stage front air seal control air leakage.