Axial Compressor Aerodynamics

Question 1

What is the stage of an axial compressor?

Answer 1

Stage = Rotor and Stator

Question 2

What does more stages result in?

Answer 2

A greater pressure ratio

Question 3

What is a way of increasing pressure ratio?

Answer 3

Make each stage work harder

Question 4

What is the working fluid accelerated by?

Answer 4

Rotor

Question 5

What is the working fluid decelerated by

Answer 5

Stator

Question 6

Where does deceleration occur?

Answer 6

Deceleration occurs in stator and in the relative frame of rotor (i.e. if you are sitting on the rotor blades spinning round)

Question 7

Why is aerofoil design critical?

Answer 7

To avoid stall

Question 8

What’s the definition of reaction?

Answer 8

The ratio of static enthalpy rise in rotor to static enthalpy rise in stage

Question 9

Why is the reaction important?

Answer 9

If it turns negative, a compressor will act as a turbine and a turbine will act as a compressor. Not ideal!

Question 10

What are some causes of stall?

Answer 10

Damaged compressor components caused by ingestion of foreign objects
Worn or contaminated components such as eroded rotor compressor blades and seals
Dust and dirt in the compressor can reduce its efficiency and lead to a stall if the contamination is severe enough