Overview
Primarily, the combustion section adds fuel to the compressed air and burns it. This causes the gases to expand which increase the speed of airflow to turn the engine turbines.
The air from the compressor section moves into the combustion section. The combustion section mixes fuel with compressed air. The fuel nozzles use the combustion case airflow in the combustion chamber to make the fuel/air mixture. The air and fuel mixture burns after ignition from the ignition system. The hot gases expand which causes increased airflow speed to turn the engine turbines.
The combustor support gives support for the combustion chamber. The combustor support absorbs the axial loads between the high-pressure turbine (HPT) fuel nozzles and the combustor case. The air moves through the combustor support to give cool air to the HPT.
01/04/16
Combustor
The combustor mixes the fuel from the fuel nozzles with high pressure (HP) compressed air. Ignition occurs, and the fuel/air mixture burns in the combustor which makes hot gases that expand and turn the HPT. The HPT changes this energy to mechanical energy to turn the compressor.
The engine combustor includes the following components:
Combustor Case
The combustor case is a one piece cylindrical structure with flanges at the open ends. There are 16 fuel nozzle bosses installed at equal intervals around the combustor case, adjacent to the forward flange. Each boss has holes with threads for the bolts to attach the fuel nozzle. The igniter plug bosses are at the 4 and 8 o’clock positions of the combustor case. There is a combustor case drain at the bottom of the combustor case to drain unwanted fuel.
There is a P3 air source at the top of the combustor case. The P3 air source gives input to the engine control unit (ECU) and borescope access to the HPT. The front flange of the combustor case attaches to the rear flange of the compressor diffuser case. The rear flange of the combustor case attaches to the front flange of the LPT housing.
There is a T3 port on the combustor case for the instrumentation test during an engine performance operation.
Combustion Chamber Assembly
The outer liner, inner liner, and dome are three assemblies that make up the combustion chamber assembly. The inner surfaces of the combustion chamber assembly have thermal barrier coated material, and it is a one-piece annular through-flow flow assembly. There are 16 swirlers attached to the dome assembly. Each swirler turns the air flow to mix the compressed discharge air with the fuel from the fuel nozzles. Effusion holes in the combustion chamber assembly send in air to make a boundary layer to decrease the temperature of the walls of the combustion chamber assembly. The control of temperatures helps to make the inner liner carbon resistant.
Combustor Support
The combustor support provides support for the combustor, HPT stage 1 nozzle and the combustor outer wall. The air moves through the combustor support to cool the air to the HPT.
Combustor Case Drain
The combustor case drain drains the unwanted fuel after a cancelled start or a wet motoring of an engine. It also drains the flammable fluid from a component malfunction. The combustor case drain has a spring-loaded valve which opens when the combustor internal pressure decreases on shutdown.
01/05/16
Operation
High-pressure compressed air goes from the centrifugal compressor impeller into the diffuser. In the diffuser, the airflow speed decreases and the pressure increases before the air goes into the combustor case. The air goes into the combustor through holes in the dome area and the inner and outer liner walls. The air then goes through the swirlers at the 16 airblast fuel nozzles to mix with the fuel from the airblast fuel nozzles. The igniter plugs that extend into the combustion chamber assembly ignite this fuel/ air mixture. The fuel/air mixture burns in the combustor to add heat energy to the gases. When the temperature increases, the gases expand which increase the speed of the gas flow into the turbine section. The turbine section changes this energy to mechanical energy to turn the compressor and engine accessories.