M15.12 Air Systems Flashcards
Air system sub-systems
- Compressor control
- Clearance control
- Engine cooling
What does compressor control do
Protects engine compressors against surge and stall in all conditions
Increase efficiency
What does clearance control do
Optimises tip clearance between rotor and stator casing in increase efficiency
What does engine cooling do
Ensures correct cooling sufficiently during operation and after shut down
Compressor control common subsystems
- VBV system
- VSV system
- HPC bleed valve system
What controls the compressor control systems
- Hydro mechanical fuel control unit or FADEC
What component is used within the HPC with VSVs to improve engine at start and acceleration
Start bleed valves (HPC bleed valves)
Where are clearance control systems normally located
HP and LP turbine
And sometimes HPC
Types of clearance control
Active or passive
Which clearance control system cannot be turned off
Passive
Main component difference between active and passive clearance control
Cooling air control valves in active cc
What is different in the clearance control of a turbine and compressor
In a compressor it uses warm air to heat the rotor instead
Why is warm air used in compressor clearance control
Air is not cold enough to cool the compressor case sufficiently
Cooling system sub-systems
Internal cooling
External cooling
Where does external cooling act
Into the cavities between the engine cowlings and the engine cases
