This document provides an overview of different types of turbines used for energy conversion. It discusses steam turbines, which are used in power plants to convert the energy of high pressure steam into mechanical power. It describes impulse and reaction steam turbines and examples of each. It also discusses gas turbines, which produce pressurized gas by burning fuel and use the high-speed rush of hot air to spin a turbine, and are used to produce large quantities of power compactly. Finally, it briefly mentions wind turbines which similarly convert the kinetic energy of wind into mechanical power.

1. Unit No:02
Energy Conversion Devices
Prof. Yash B. Parikh
M.Tech (Computer Integrated Manufacturing)
B.E.(Mechanical Engineering)
Assistant Professor
Department of Mechanical Engineering

2. 2

3. Preface
3
 When you go to an airport and see the commercial
jets there, you can't help but notice the huge engines
that power them.
 Most commercial jets are powered by turbofan
engines, and turbofans are one example of a general
class of engines called gas turbine engines.
 You may have never heard of gas turbine engines,
but they are used in all kinds of unexpected places.
 For example, they are used in many of the
helicopters, smaller power plants and even in the M-1
Tank.

4. History
4
 The word "turbine" was coined in 1822 by the French
mining engineer Claude Burdin.
 It’s derived from the Latin word turbo, which means
a spinning object.
 During the 18th and 19th centuries, much progress
was made toward extracting the kinetic energy of
flowing water.
 This in turn devised water turbines.

5. Introduction
5
 Turbines are devices that spin in the presence of a
moving fluid.
 A turbine looks like a large wheel with many small
radiating blades around its rim.
 There are four broad classes of turbine:
water (hydraulic), steam, wind, and gas.
 The most important application of the first three is
the generation of electricity; gas turbines are most
often used in aircraft.

6. Steam Turbine
6
 Most power plants use coal, natural gas, oil or
a nuclear reactor to create steam.
 A steam turbine is a rotary machine which is
designed to convert the energy of high pressure and
high temperature steam into mechanical power.
 The steam runs through a huge and very carefully
designed multi-stage turbine to spin an output shaft
that drives the plant's generator.

7. Principle of Operation of Steam Turbine
7
 The high pressure-low velocity steam is first
expanded in a passage (called as a nozzle) which
converts the steam into low pressure-high velocity jet
of steam.
 The resultant high velocity steam is passed over the
curved vanes (or blades).
 Due to this, there is a change in momentum and it
will exert a resultant force on the blades.
 These blades are attached to a disc on a shaft which
is free to rotate.
 The resultant force cause the rotor to rotate, and
thus the power is developed.

8. Types of Steam Turbine
8
 There are mainly two types of steam turbines :
1. Impulse Turbines
2. Reaction Turbines

9. Impulse Turbine
9
 These turbines use the principle of impulse.
 In which the stationary nozzles are used to exert a
force on a ring of moving blades.

10. Impulse Turbine
10
 Impulse turbines convert the kinetic energy of a jet
of water to mechanical energy.
 e.g. Pelton Wheel

11. Reaction Turbine
11
 Reaction turbines convert potential energy in to
mechanical energy.
 Reaction turbines develop torque by reacting to the
fluid's pressure or mass.

12. Reaction Turbine
12
 These turbine does not use nozzles.
 Water flow is radial from exterior to interior.
 Flow changes gradually from radial to axial.
 The pressure of the fluid changes as it passes
through the turbine rotor blades.

13. Reaction Turbine
13
 The overall efficiency of a reaction turbine is slightly
higher than the equivalent impulse turbine for the
same thermal energy conversion.
 e.g. Kaplan Turbine, Francis Turbine.

14. Difference between Impulse & Reaction Turbine
14
 In an impulse turbine entire pressure energy is
converted in to kinetic energy (as in case of a pelton
turbine where the nozzle does this).
 In a reaction turbine only a part of the pressure
energy is converted to kinetic energy (as in case of
Francis and Kaplan turbines.)
 Impulse turbine is less efficient compared to reaction
turbine.
 In impulse turbine we get as high as 30,000 rpm
speed of rotor which is very difficult to handle.
 In reaction turbine rotor speeds are relatively low.
 Impulse turbines occupies less space than reaction
turbines.
 Impulse turbines are used for small scale applications

15. 15

16. Introduction
16
 A gas turbine is an extension of the same concept
as that of steam turbines.
 In a gas turbine, a pressurized gas spins the turbine.
 In all modern gas turbine engines, the engine
produces its own pressurized gas, and it does this by
burning something like propane, natural gas,
kerosene or jet fuel.
 The heat that comes from burning the fuel expands
air, and the high-speed rush of this hot air spins the
turbine.
 Gas turbines are used to produce large quantities of
power in a self contained and compact unit.
 It has got low weight to power ratio than that of
I.C.Engines.

17. Introduction
17
 Wind turbines, also known as wind mills, use the
wind as their motive force.
 A wind turbine looks nothing like a steam turbine or a
water turbine because wind is slow moving and very
light, but again, the principle is the same.