1. Fans, Compressors & Turbines for Jet Engines
P M V Subbarao
Professor
Mechanical Engineering Department
Life Management Systems for A Flying Machine.

2. Fans & Compressors

3. Euler Turbo-machine Equation
Vwhirl, out
Vwhirl, in
Applying conservation of angular momentum,
the torque, T, must be equal to the time rate of change of angular momentum in a stream tube that flows through the device

4. Axial Flow Turbo-machines
Fan or compressor Rotor Blades
The power, P of a fluid Machine

5. Action & Reaction
If the tangential velocity increases across a moving blade then work is added to the flow ( a fan or a compressor).
If the tangential velocity decreases across a moving blade then work is removed from the flow (a turbine).

6. Classification of Fans & Compressors
Roto-dynamic Compressors
Positive Displacement of Compressors
Reciprocating
Compressors
Rotory
Centrifugal
Compressors
Hybrid
Compressors
Axial
Compressors

7. Multistage Axial flow fans & Compressors

8. Schematic representation of a multi stage axial flow compressor

9. Need for a Stator in multi-stage fan or compressor
In general, a rotor also adds kinetic energy along with enthalpy to the fluid.
A diffuser known as stator succeed the rotor to convert the excess kinetic energy into enthalpy.

10. Thermodynamics of An Ideal Axial flow fan/Compressor Stage
p02 = p03
T02 = T03
V32/cp p3
V22/cp p2 T
p01
T01
V12/cp p1 T1 s

11. Euler’s Action behind the increase in Enthalpy of Air

12. Mean Stream line Kinematics of An Ideal Axial Flow fan/ Compressor Stage
Inlet Velocity Triangle
Outlet Velocity Triangle

13. Kinetics of An Axial Flow Fan/Compressor Stage
Rate of Change of Momentum:
Power Consumed by an Ideal Moving Blade
Inlet Velocity Triangle
Current Design Practice:
Outlet Velocity Triangle

14. Energy Analysis of An Axial Flow Fan /Compressor Stage
Change in Enthalpy of fluid in moving blades:
Inlet Velocity Triangle
Outlet Velocity Triangle

15. Level of Compression in A Rotor
Power consumed by an ideal rotor :
Power absorbed by fluid in a rotor :
First law for relative flow through moving blades:
Isentropic compression in A Rotor Blade
Degree of Reaction of A Stage

16. Total Effect by an isentropic Stage of a Fan /compressor:

17. 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