M15.12 Flashcards
What is the job of the compressor control system?
To protect the engine compressor against stall, surge and increases efficiency
What is the job of the clearance control system?
To optimise the tip clearance between the rotor blades and the stator casing
How does the compressor control system protect the engine from stall and surge?
By using variable bleed valves that control the airflow to the high pressure compressor
Where are the variable bleed valves located?
In the fan frame behind the low pressure compressor
What are the two ways to protect the high pressure compressors against stall and surge?
- compressor bleed valves
- variable stator vanes (control airflow)
What are start bleed valves?
They’re variable bleed valves only used at the engine start sequence
What are clearance control systems used for?
To optimise the tip clearances in turbines and compressors
What is passive clearance control system?
It uses cooling airflow that cannot be switched off
What is active clearance control systems?
They use cooling air control valves to optimise cooling
What are the active clearance control valves usually controlled by?
The hydro mechanical fuel control unit or by the FADEC system
What type of air does compressor clearance control systems use?
Uses warm air to heat up the compressor rotor
What is the engine cooling system divided into?
External cooling system and internal air system
What is the pressure balancing used for?
Too releases axial loads on the thrust bearings
What is the LP compressor bleed air used for?
Sealing of the engine bearing compartments
Where does the air that enters the bearing compartment vent from?
The hollow N1 rotor shaft
