15.12 Flashcards
Where can clearance control systems be found
At HP and LP turbines and sometimes at HP compressor
What are the two methods to protect HP compressor from stalling and surge
Using a compressor bleed valve and using variable stator vanes
What is a bowed rotor
When the engine bends due to different expansion between upper and lower zones
What do the variable bleed valves (VBVs ) do?
Control the airflow to the high pressure compressor
The subsystem of the compressor control system is controlled by what
The FADEC System or bay the hydro-mechanical fuel control unit
What are the common tasks of the internal air system
Internal sealing
Pressure balancing
Internal cooling
What type of air is used to cool the core compartment
Fan air
What is used for the sealing of the engine bearing components
LP compressor bleed air
How is the engine cooled at engine shut off
By convection
What do the variable stator vanes do?
Control the incoming airflow onto the HP compressor
What type of air is used for the cooling of the fan compartment
RAM air
What are internal pressure distribution also known as
Pressurebalancing
What are clearance control system used for?
To optimise the tip clearance in turbines and compressor
How is the core compartment cooled
By fan air
What can a bowed rotor condition lead to?
Hung start or to rotor wear
What does the clearance control system do
Optimises the tip clearance between the rotor blades and the stator casing
What are the subsystems of an engine air system
Compressor control
Clearance control
Engine cooling
All three are fully independent
What type of air does compressor clearance control system use
warm air to heat the rotor
The area below the engine cooling are divided into what
Fan compartment and core compartment
What are the subsystem of the compressor control system
Variable bleed valve system
Variable stator vans system
HP compressor bleed valve system
What does the compressor control system do
Protect the engine compressor from stalling and surge
What can the engine cooling system be divided into
External cooling system and internal air system
What does the engine cooling system do
Makes sure that the internal and external engine components are cooled
