Module 15.12 Air systems Flashcards
Large volumes of air provides cooling and maintains temperature to what acceptable range?
800 to 1150℃
Where is secondary air for cooling taken from?
Early stages of the compressor
Secondary air is used to cool what?
- Turbine discs, blades and vanes
- Exhaust bearing
What is zone 1?
Area around the fan case
What is zone 1 cooled by?
Ram air
What is zone 2 cooled by?
Fan air
Enters in the upper part of the duct and is exhausted into fan air at the low end
What is zone 3?
Area around the high pressure compressor to the turbine cases
How can anti ice systems be operated?
Manual or automatically
What are the turbine temperatures at the rear stages of the compressor?
350 to 400℃
How is the compressor cooled?
Compressor air cools the compressor from the IP/LP
How much air in the combustion chamber is used for transpiration and film cooling?
70-80%
What is one major limiting factor of GTE’s?
Temperature of the turbine section
To limit the effect in temperature variations cooling air is directed over what?
Each side of the disc
How does cooling flow enter the turbine blade?
Inlet at the butt of the blade
What air is used to cool the NGV’s?
Compressor discharge air from the exit guide vanes
What bleed air is used for sealing of engine bearing chambers?
Low pressure compressor bleed
Pressurised air acting on the air and oil seals has what additional sealing effect?
Prevents oil from escaping the bearing chamber
Where is the sealing air vented overboard?
Through the hollow N1 rotor shaft
What secondary function/external air services are supplied by the compressor? (What is bleed used for)
- Cabin pressurisation, heating and cooling
- De-ice and anti-ice
- Pneumatic engine start
- Auxiliary drive units
The external cooling system cools and ventilates what areas?
Area between cowling and engine cases
What is a bowed rotor caused by?
Engine bending due to differences in expansions
What does the external cooling system ensure?
All components in the fan and core components are sufficiently cooled