1. Design of An Axial Compressor Stage for Jet Engines
P M V Subbarao
Professor
Mechanical Engineering Department
Efficient Infrastructure to Infuse Life into Air...

2. Irreversible Adiabatic Stage of an Axial Flow Fan/Compressor
p03s=p02s
p02
p03
T03=T02
Rotor Losses
Total Losses
T02s
T03s T
p01
T01 s

3. Real Flow Past Compressor Blades

4. Stage Efficiency of a fan or Compressor
For a required pressure ratio of a stage, rop,stage
The power consumed by an irreversible stage is always higher than a reversible stage.
Define stage efficiency as

5. Actual pressure Ratio of A fan or Compressor Stage

6. Compressor Blade geometry
Vr1
Vr2
i Incidence angle, 1 -  b1
 Deviation angle, 2 -  b2

7. Selection of Design Parameters
A high pressure rise per stage will decrease the number of stages for a given overall pressure rise.
A high pressure rise per stage is obtained using:
High blade speed.
High inlet flow velocity.
High fluid deflection in rotor blades.

8. Blade Speed
For a given rotor speed the velocity of the blade at the tip will be maximum.
The centrifugal stress in the rotor blades depends on the rotational speed, the blade material and length of the blade.
The maximum centrifugal stress is given by,
b, hub-tip diameter ratio.
K varies in the range 0.55 – 0.65.

9. Selection of Absolute Inlet Velocity
Va1
Vr1

10. Selection of Flow velocity & Losses
Vf/U
Annulus Loss
Secondary Loss
Profile Loss

11. Fluid Deflection

12. Effect of Diffusion Factor on Frictional Losses
Rotor Tip Losses
Rotor Hub and Stator losses

13. Multi Stage Compression
Loss in capacity due to variation of velocity is defined as work done factor.
Work done factor, l, decrease with number of stages.

15. Sizing of A Compressor Stage
There are five Primary non-dimensional variables
Stage load coefficient or Work input coefficient
Stage flow coefficient
Stage reaction, R
de Haller number, dH

16. Holistic Method of Mean Line Design
Vr1
Va1 Va
Vr2
Va2
Va3
Vr1
Va1
Va2
Vr2 Vf
Vw

17. Smith Design Chart : R=50%

18. Smith Design Chart – R = 60%

19. Smith Design Chart – R = 70%

20. Irreversible Flow through Multi Stage Fan & Compressor
1VIs
4VIa 2s
1Vs
4Va
1IVs
4IVa
1IIIs
1IIIa T
1IIs
1IIa
1Is
1Ia 1 s

21. Variable Speed operation of Compressor

22. Hybrid Compressor