DOC AIRBUS | AMM A320FLPT ACTIVE CLEARANCE CONTROL (ACC) SYSTEM - DESCRIPTION AND OPERATION
** ON A/C NOT FOR ALL
1. General
The low pressure turbine case is cooled by fan discharge air sprayed through an array of pipes and small air jets on the outside surface of the case. The Low Pressure Turbine Active Clearance Control (LPTACC) system controlled by a valve through FADEC system, maintains Low Pressure Turbine (LPT) case shroud clearances relative to LPT rotor blade tips.
** ON A/C NOT FOR ALL The low pressure turbine case is cooled by fan discharge air sprayed through an array of pipes and small air jets on the outside surface of the case. The Low Pressure Turbine Active Clearance Control (LPTACC) system controlled by a valve through FADEC system, maintains Low Pressure Turbine (LPT) case shroud clearances relative to LPT rotor blade tips.
2. Description
The LPTACC system is located on the left of the High Pressure Compressor (HPC) case at the 9 o'clock position. The system is routed aft and surrounds the LPT case.
The function of the LPTACC system is to regulate cooling-air flow to the exterior of the LPT case.
This cooling-air is used to minimize the clearances between the LPT shrouds and the LPT rotor blades. The reduction in clearances improve the specific fuel consumption. The Electronic Engine Control (EEC) uses the sensor inputs and modulates the fuel actuated LPTACC valve during engine operation.
The LPTACC valve controls the quantity of fan discharge air delivered to the LPT air manifold. The operation of the LPTACC valve is performed by the EEC with servo fuel. The servo fuel drives an actuator which rotates the butterfly valve shaft. Dual Linear Variable Differential Transducer (LVDT), attached to the actuator, provide valve position feedback through separate cables to each EEC channel.
The LPTACC system is located on the left of the High Pressure Compressor (HPC) case at the 9 o'clock position. The system is routed aft and surrounds the LPT case.
The function of the LPTACC system is to regulate cooling-air flow to the exterior of the LPT case.
This cooling-air is used to minimize the clearances between the LPT shrouds and the LPT rotor blades. The reduction in clearances improve the specific fuel consumption. The Electronic Engine Control (EEC) uses the sensor inputs and modulates the fuel actuated LPTACC valve during engine operation.
The LPTACC valve controls the quantity of fan discharge air delivered to the LPT air manifold. The operation of the LPTACC valve is performed by the EEC with servo fuel. The servo fuel drives an actuator which rotates the butterfly valve shaft. Dual Linear Variable Differential Transducer (LVDT), attached to the actuator, provide valve position feedback through separate cables to each EEC channel.