Compressor stall & surge

Question 1

What are axial compressors sensitive to?

Answer 1

Airflow changes

Question 2

The airflow into a rotor will be smooth as long as what?

Answer 2

Rotor blades AOA is small

Question 3

What do stator vanes do?

Answer 3

Decelerate the airflow & guide it to the next rotor stage of the compressor

Question 4

What happens if rotor speed or inlet velocity changes?

Answer 4

Angle of attack changes

Question 5

What happens when angle of attack on the compressor changes?

Answer 5

Airflow separation occurs and a turbulent vortex occurs causing compressor stall

Question 6

What is compressor surge?

Answer 6

A very severe form of compressor stall

Question 7

What can compressor surge be generated by?

Answer 7

-rapid decrease of airflow causes stall on some blades or stages
-stall causes blockage in airflow which leads to stronger stall in subsequent stages
-causes low pressure zones in which the airflow comes to a stop & reverses its direction

Question 8

What mistakes can the pilot make to cause a stall?

Answer 8

Letting the engine go too slow
Incorrect acceleration or deceleration