Fluid Dynamics to Create High Performance Steam & Gas Turbines P M V Subbarao Professor Mechanical Engineering Department Realization of Thermodynamic.

Fluid Dynamics to Create High Performance Steam & Gas Turbines

P M V SubbaraoProfessor

Mechanical Engineering Department

Realization of Thermodynamic Understanding ……

Advanced 700 8C Pulverised Coal-fired Power Plant Project

Some Facts about Advanced Steam Turbines

Increased Magnitudes of Forces

The First Proposal onInfrastructure for Realization of Newton's’ Laws

Stator

Rotor

Axial Turbine Stator Exit/Rotor Inlet Velocity Triangle

Va0

Vf0

Va1

Vf1

Vw1

Va1

Vr1

1

Vw1

Vf1

1 1

U

Vr1

Vr2

Va1

UVr1

Va1

Inlet Velocity Triangle

Exit Velocity Triangle

U

Vr2

Va2

Kinematics of Flow Past A Rotor Blade

U

Vr1Va1

Vr2

Va2

112 2

Va1: Inlet Absolute VelocityVr1: Inlet Relative VelocityVr2: Exit Relative VelocityVa2:Exit Absolute Velocity

1: Inlet Nozzle Angle.1: Inlet Blade Angle.2: Exit Blade Angle.2: inlet Nozzle Angle (next stage).

Newton’s Second Law for an Impulse Blade:The tangential force acting on the jet is:F = mass flow rate X Change of velocity in the tangential directionChange in velocity in tangential direction: -Vr2 cos(2) – Vr1 cos(1).

-(Vr2 cos(2) + Vr1 cos(1)).Tangential Force,

1122 coscos rrA VVmF

U

Vr1Va1

11

Va2

2

Vr2

2

The reaction to this force provides the driving thrust on the wheel.

The driving force on wheel 1122 coscos rrR VVmF

Power Output of the blade :

1122 coscos rrb VVUmP

Diagram Efficiency or Blade efficiency:

steam ofPower KineticInput

ouputPower d

2

coscos21

1122

a

rrd

Vm

VVUm

1111 coscos ra VUV

1

111 cos

cos

UV

V ar

Power Output of the blade : 1122 coscos rrb VVUmP

For impulse blading with inviscid flow

121 coscos brb kUVmP

For blading with frictional flow

U

Vr1Va1

Vr2

Va2

112 2

1

cos

coscos

1

211

bab kUVUmP

2

coscos21

1122

a

rrd

Vm

VVUm

U

Vr1Va1

Vr2

Va2

112 2

1

cos

coscos2

1

2

11

1 b

aad k

V

U

V

U

For a given shape of the blade, the efficiency is a strong function of U/Va1called blade speed ratio,

1

cos

coscos2

1

21

bd k

1cos

cos2cos2

1

21

bd k

1cos

cos4

1

22

2

bd k

Condition for maximum efficiency:2

cos 1

Maximum efficiency:

1

cos

cos

2

cos

1

212

max, bd k

U

Vr1Va1

Vr2

Va2

112 2

Availability of Steam for Condenser Temperature of 450C

Turbine Inlet : 3500

kJ/kg Turbine Exit

Specific Available Jet Velocity

Pressure Temp Enthalpy Work

MPa C kJ/kg kJ/kg m/s

1 1 509.9 2464 1036 1439

2 5 528.4 2232 1268 1592

3 10 549.6 2135 1365 1652

4 15 569 2080 1420 1685

5 20 586.7 2041 1459 1708

6 25 602.9 2012 1488 1725

7 30 617.7 1989 1511 1738

8 35 631.3 1969 1531 1750

de Laval Turbine : The First Design for Steam Turbine

• de Laval turbine is an impulse turbine : An enormous velocity (30,000 revolutions per minute in the 5 H. P. size) is requisite for high efficiency, and the machine has therefore to be geared down to be of practical use.

Creation of Wonderful Concept with Deep Fluid Dynamics & it is Still Valid?!?!?!

The creator had a long term vision in Developing a

Sustainable & Economically Viable Non-biological

Beast……

An Invention that Made abundance of Electricity at Very Cheap

• The modern steam turbine was invented in 1884 by the Englishman Sir Charles Parsons.

• The first model was connected to a dynamo that generated 7.5 kW (10 hp) of electricity.

• The invention of Parson's steam turbine made cheap and plentiful electricity possible and revolutionized marine transport and naval warfare.

• His patent was licensed and the turbine scaled-up shortly after by an American, George Westinghouse.

• The Parson's turbine also turned out to be easy to scale up.

A Device Easy to Scale up

• Parsons had the satisfaction of seeing his invention adopted for all major world power stations, and the size of generators had increased from his first 7.5 kW set up to units of 50,000 kW capacity.

• Within Parson's lifetime the generating capacity of a unit was scaled up by about 10,000 times.

• The total output from turbo-generators constructed by his firm C. A. Parsons and Company and by their licensees, for land purposes alone, had exceeded thirty million horse-power.

Classification of Steam Turbines

The most powerful steam turbine-generator in the world at the time of it's construction:1903

Built in 1903, the 5,000-kilowatt Curtis steam turbine-generator was the most powerful in the world. It

stood just 25 feet high, much shorter than the 60 feet

reciprocating engine-generator of a similar capacity