DOC AIRBUS | AMM A320FLPT ACTIVE CLEARANCE CONTROL SYSTEM - DESCRIPTION AND OPERATION
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
1. General
The low pressure turbine casing is cooled by fan discharge air. The air is sprayed through an array of piping and small air jets that impinge on the outside surface of the casing.
The LPT active clearance control system is controlled by a valve through FADEC system. It maintains LPT case shroud clearances relative to LPT rotor blade tips.
** ON A/C NOT FOR ALL The low pressure turbine casing is cooled by fan discharge air. The air is sprayed through an array of piping and small air jets that impinge on the outside surface of the casing.
LPTCC - SchematicThe LPT active clearance control system is controlled by a valve through FADEC system. It maintains LPT case shroud clearances relative to LPT rotor blade tips.
2. Description
The clearance control system supply fan bleed air from the inner barrel scoop of the thrust reverser to the LPT casing. The air is distributed via circular pipings fitted around the shroud support structure. The fan bleed air flow is modulated by the ECU according to engine operating conditions.
** ON A/C NOT FOR ALL The clearance control system supply fan bleed air from the inner barrel scoop of the thrust reverser to the LPT casing. The air is distributed via circular pipings fitted around the shroud support structure. The fan bleed air flow is modulated by the ECU according to engine operating conditions.
A. Description
LPT clearance control valve is a butterfly valve, the valve consists of an outer housing, a control plate, a linear actuator, 2 RVDT sensors for feedback signals and a butterfly valve actuation.
Under control of the PCR pressure applied at its head end and a PC/PB modulated pressure applied at its rod end, the linear actuator moves a rack. This controls both the opening and closing of the butterfly valve. The valve regulates the amount of air required for cooling the turbine as a function of the engine operating configuration (engine rating).
LPT clearance control valve is a butterfly valve, the valve consists of an outer housing, a control plate, a linear actuator, 2 RVDT sensors for feedback signals and a butterfly valve actuation.
Under control of the PCR pressure applied at its head end and a PC/PB modulated pressure applied at its rod end, the linear actuator moves a rack. This controls both the opening and closing of the butterfly valve. The valve regulates the amount of air required for cooling the turbine as a function of the engine operating configuration (engine rating).
B. Operation
The ECU modulates the pressure of one of the piston chambers through the HMU.
The HMU supplies a reference pressure to the second chamber.
The ECU controls the travel of the piston and valve butterfly according to the engine parameters.
The butterfly of the valve opens when the engine rating increases and closes when it decreases.
When the engine is shut down, the valve butterfly is fully open.
The ECU modulates the pressure of one of the piston chambers through the HMU.
The HMU supplies a reference pressure to the second chamber.
The ECU controls the travel of the piston and valve butterfly according to the engine parameters.
The butterfly of the valve opens when the engine rating increases and closes when it decreases.
When the engine is shut down, the valve butterfly is fully open.
4. LPT Cooling Flow Function
LPT cooling airflow, controlled by LPTACC valve depends on the operating conditions and engine characteristics. Flow functions defined are validated for ventilation calculation purpose.
LPT cooling airflow, controlled by LPTACC valve depends on the operating conditions and engine characteristics. Flow functions defined are validated for ventilation calculation purpose.