DOC AIRBUS | AMM A320FHIGH PRESSURE COMPRESSOR (HPC) - DESCRIPTION AND OPERATION
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
1. General
A. High Pressure Compressor (HPC)
(1) The HPC increases the speed, pressure and temperature of the primary gaspath air and supplies this air to the diffuser and combustor. There are eight stages to the HPC. The Variable Inlet Guide Vanes (VIGVs) (part of the compressor intermediate case) and the first three stages of vanes in the HPC are variable. The 4th to 7th stage stators are fixed (cantilevered) and seal against the adjacent rotor abrasive. Knife edge seals on the rotors seal against the stator vanes. The rotor stages are held together with a rotor shaft. This shaft connects the front hub with the rear hub and extends rearward to the High Pressure Turbine (HPT). The HPC is held radially and axially at the front by the No. 3 bearing. It is held radially at the rear by the No. 4 bearing. The outer case wall is made of the front case set between the CIC and the diffuser case. The outer air seals make the inner case wall. The HPT supplies torque to the HPC. A rotor nut at the rear hub holds the HPC rotor assembly together. The compressor supplies air to the customer bleed system and other engine systems. The front six stages of the rotor are decreased in temperature by bleed air. The rear two stages of the compressor are compartmentalized from the front by a ring on the rotor shaft. The rear rotor compartment temperature is controlled by airflow slots in the spacer and the rotor tube assembly.
2. Description of the High Pressure Compressor (HPC) Module
High Pressure Compressor (HPC) ModuleA. There are eight stages to the HPC, with numbers that start with stage 1. See the sheets 2 and 3 of the figure.
(1) The first eight rotor stages are of the integral blade rotor design, in which the disk and blades are one piece to decrease air leakage.
(2) The eight rotor stages are held together with a tie shaft that connects the HPC front hub and rear hub, and extends rearward to the High Pressure Turbine (HPT).
B. The first three stages of the HPC stator vanes are variable-vane design, in which the vane angles are adjusted as necessary for engine operation conditions.
(1) A dual actuator controlled by the Electronic Engine Control (EEC) moves a linkage to turn the vanes of each stage at the same time to the necessary angle.
(2) Knife-edge seals on the 2nd through 4th stage rotors seal against the inner seal lands of the variable stators to control the flow of the air.
C. The HPC gets its power from the HPT system. See the sheets 2 and 4 of the figure.
(1) The HPT engages at the front to the HPC rear hub through a curvic coupling and is held together by a retaining nut on the HPC tie shaft at the rear.
(2) The HPC is held radially and axially at the front by the No. 3 ball bearing in the compressor intermediate case. It is held radially at the rear by the No. 4 roller bearing at the end of the HPC tie shaft.
D. Between the 7th and 8th stage rotors are eight HPC rotor tubes held in a ring. See the sheet 3 of the figure.
(1) These paddles turn with the rotor and push air to the center of the rotor where this air can flow to where it is necessary for cooling and pressure balance.
(2) These paddles prevent vortices which can cause blockage of necessary internal rotor air movement.