1. Power Plant Steam Turbines
P M V Subbarao
Professor
Mechanical Engineering Department
I I T Delhi
A Two Step Conversion of Microscopic Kinetic Power to Shaft Power…….

2. The Steam Turbine
The more modern method of extracting mechanical energy from thermal energy is the steam turbine.
Steam turbines have been the norm in various land based power plants for many years.
Turbine is a flow device develops a variable pressure form inlet to outlet.
A flowing steam develops work transfer due to movement of steam from High inlet pressure (Live Steam) to low outlet pressure (Dead Steam).
The volume of steam continuously increase during this process.
The infinitesimal work done by a flowing fluid is defined as
- Sign is important part of this definition

3. Thermodynamic Validation of Flowing Steam WorkVi Ub Ve
Work is said to be done by a system iff
the sole effect external to the system
can be reduced to raising of weight

4. Analysis of Simple Stationary Impulse Blade
Consider a stationary 180 degree curved blade.
A jet with a velocity Vi incidence on the blade.
The blade deflects the jet along its surface and finally the jet leaves with a velocity Ve.
The magnitude of velocity vector remains unchanged.
However, the direction changes through 180 degrees.
Ve = - Vi
The change in velocity : - 2 Vi.
A jet with a finite mass flow rate will experience a rate of change of momentum, FA: Vi Ve FA FR
The force acting on the blade:
However, this force is not doing any work ?!?!.

5. Analysis of Simple Moving Impulse Blade
Vre = -Vri
Vae = Vre -Ub U Ub
Vri = Vai - Ub
Vai

6. The Power Transaction Between Steam & Impulse Blade
Kinetic power lost by the jet :
Power lost by jet = Power gained by the Blade
Initial Power of the jet :
Thermodynamic efficiency of an impulse blade :

7. Analysis of Simple Reaction BladeUb
Vai
Vri
Vre
Vae
Change in velocity :
Motive Power Generated:

8. The Power Transaction Between Steam & Reaction Blade
Motive Power Generated:
Thermodynamic efficiency of a Reaction blade :

9. Simple Impulse-Reaction Blade
Vai
Vae
Vri
Vre Ub
Jet will lose power both by Impulse and Reaction.
One important and essential element in all these cases is finite inlet steam velocity.

10. Continuous Generation of Power
How to introduce finite mass flow rate of steam?
Area for Flow of Fluid.
Proportional to the Length of the Blade.
More Number of Blade Spacings.

11. Nozzle wheel and Blade Wheel

12. Structure of A Basic Turbine

13. Fixed Blade Wheel

14. Moving Blade Wheel

15. The Flow Device Power System

16. Axial Turbine Stator Exit/Rotor Inlet Velocity Triangle
Va1
Va1
Vw1
Vr1
Vw1 b1
Vf1
Vf1
Va0
Vf0

17. Top View of the Steam & Blade Interactions
Va1 U
Vr1
Va1
Inlet Velocity Triangle
Vr1 U U
Vr2
Va2
Exit Velocity Triangle
Vr2

18. The Velocity TrianglesU a2 a1 b2 b1
Va1
Va2
Vr1
Vr2
Va1: Inlet Absolute Velocity
Vr1: Inlet Relative Velocity
Vr2: Exit Relative Velocity
Va2:Exit Absolute Velocity
a1: Inlet flow Angle.
b1: Inlet Blade Angle.
b2: Exit Blade Angle.
a2: Exit flow Angle.