Compressor Flashcards
Role of the Compressor
Increase the mass flow by increasing pressure and temperature.
Pressure Ratio
Compressor Outlet : Compressor Inlet
What increases velocity and temperature, even though the compressor is divergent?
Centrifugal force
Axial Flow Compressor is made up of?
Series of rotating rotors and stationary stators
Pressure ratio of an axial flow compressor
1.1 or 1.2:1
Define a “stage”
A series of rotors and stators
What happens to P, V, T in a rotor?
Pressure increases, Velocity Increases, Temperature increases.
What happens to P, V, T in a stator?
Pressure increases, velocity decreases, temperature increases.
Surges
If one stage stalls, turbulent flow occurs, if this spreads to multiple stages, a surge will occur.
Where is the compressor most effective at?
80% RPM
Causes of Surges
FOD, ice accretion, unusual attitude, damage to blades, rapid changes in fuel flow.
Where are surges most common?
At low airspeeds with high RPM.
What are symptoms of surges?
Banging noises, increase in EGT, flame out, and in worse case scenario reversal of flame.
Actions to take in a surge
Retard throttles slowly. Shut down engine if persists.
Variable Inlet Guide Vanes
Row of pivoting static vanes at inlet before first rotor.
Improves blade efficiency, ensures air directed at correct angle.
Located before HP Compressor.
