L6-9 - Axial Compressors

Question 1

What is a stage? And what does what?

Answer 1

A rotor (accelerates flow) followed by a stator (decelerates flow)

Question 2

What components make up a velocity triangle?

Answer 2

Absolute inlet velocity
Axial Component
Blade Speed
Whirl component
Relative inlet velocity

Question 3

What signifies the energy difference?

Answer 3

Difference in swirl velocity (tangential velocity)

Question 4

What is the De Haller criteria?

Answer 4

V2/V1 = 0.72 for rotor

Question 5

What is Reaction?

Answer 5

Ratio of static enthalpy rise in rotor to that in stator. If negative it means the compressor is acting as a turbine.

Question 6

Which letter represents the angle of relative inlet and outlet velocities?

Answer 6

Beta

Question 7

Where can you find steps of calculations?

Answer 7

Lecture 8

Question 8

What does a reaction of 0.5 mean?

Answer 8

Blading between rotor and stator is symetrical

Question 9

What can change the Reaction?

Answer 9

The radius.

Question 10

Where is Reaction at it’s lowest?

Answer 10

At the base of the blade, can sometimes even be negative.

Question 11

What side of the blade is the suction side?

Answer 11

Top

Question 12

What side of the blade is the pressure side?

Answer 12

Bottom

Question 13

What does higher velocity diffusion mean?

Answer 13

Greater losses

Question 14

Why do rotors and stators have different numbers of blades?

Answer 14

To avoid resonance and dynamic vibration.