Initial Designs of Turbines P M V Subbarao Professor Mechanical Engineering Department I I T Delhi Basic Models for Harvesting of Fluid Energy ….

Basic Rules for Design of An Ideal Turbine Flow Path Create highest usable form of a resource. Creation of initial velocity/kinetic energy using Stator. X1 (Impulse)+X2(Reaction)+(1-X1-X2)(centripetal) Y1 (Radial)+(1-Y1 )(Axial) Design of Flow Path using Conservation of rothalpy. Design blade cascade using conservation of mass and momentum. A design of an Ideal Machine ….. Each stage can do finite amount of action….!!! Many stages are needed to complete the action….

Advanced 700 8C Pulverised Coal-fired Power Plant Project

Some Facts about Advanced Steam Turbines

Increased Magnitudes of Forces

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.

Classification of Steam Turbine Flow Paths

Classification of Steam Turbine Flow Paths

Classification of Steam Turbine Flow Paths

Classification of Steam Turbine Flow Paths

The First Proposal on Infrastructure for Realization of Newton's’ Laws Stator Rotor

Axial Turbine Stator Exit/Rotor Inlet Velocity Triangle Va1 Va1 Vw1 Vr1 a1 a1 Vw1 b1 Vf1 Vf1 Va0 Vf0

U Vr1 Va1 Inlet Velocity Triangle Va1 Vr1 U Exit Velocity Triangle U Vr2 Va2 Vr2 Kinematics of Flow Past A Rotor Blade

U Vr1 Va1 Vr2 Va2 b1 a1 a2 b2 Va1: Inlet Absolute Velocity Vr1: Inlet Relative Velocity Vr2: Exit Relative Velocity Va2:Exit Absolute Velocity a1: Inlet Nozzle Angle. b1: Inlet Blade Angle. b2: Exit Blade Angle. a2: inlet Nozzle Angle (next stage). Isentropic Impulse Rotor

U Vr1 Va1 b1 a1 Va2 a2 Vr2 b2 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 direction Change in velocity in tangential direction: -Vr cos(b2) – Vr cos(b1). - Vr(cos(b2) + cos(b1)). Tangential Force,

The reaction to this force provides the driving thrust on the wheel. The driving force on wheel Power Output of the blade : Diagram Efficiency or Blade efficiency:

Power Output of the blade : For impulse blading with isentropic flow For blading with frictional flow U Vr1 Va1 Vr2 Va2 b1 a1 a2 b2

U Vr1 Va1 Vr2 Va2 b1 a1 a2 b2

For a given shape of the blade, the efficiency is a strong function of U/Va1, called blade speed ratio, f

Condition for maximum efficiency: Vr1 Va1 Vr2 Va2 b1 a1 a2 b2

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 m/s 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 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

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