1. 

2. INDEX

 Introduction
 Objectives
 Classification of Gas Turbine
 Applications of Gas turbine
 Methods to improve the thermal efficiency of gas
turbine
 Jet-propulsion
 Types of jet engines
 Rocket engine

3. INTRODUCTION

A gas turbine is a machine delivering
mechanical power or thrust. It does this
using a gaseous working fluid. The
mechanical power generated can be used by,
for example, an industrial device. The
outgoing gaseous fluid can be used to
generate thrust. In the gas turbine, there is a
continuous flow of the working fluid.

4. Cont…

This working fluid is initially compressed
in the compressor. It is then heated in the
combustion chamber. Finally, it goes
through the turbine.
The turbine converts the energy of the gas
into mechanical work. Part of this work is
used to drive the compressor. The
remaining part is known as the net work
of the gas turbine.

5. Objectives


After this lesson students should be
able to:
– Define what a jet engine is
– Describe how Newton’s laws apply to jet
or rocket engines
– List examples of jet engine applications
– List some key points in the history of jet
propulsion
– List advantages and disadvantages of jet
engines

6. Classification of Gas Turbine

 Constant pressure type
 Constant Volume type
 According to thermodynamic cycle
a) Brayton cycle
b) Atkinson cycle (Constant volume)
c) Ericsson cycle(Intercooler and repeaters)

7. Applications of Gas turbine

 For supercharging of I.C. engines
 Ship propulsion i.e. Marine engines
 Industrial applications. Like Crude oil pumping,
Refining processes.
 Air craft engines.
 Electric power generation.
 For the turbojet and turbo propeller engines.

8. Open Cycle gas turbine

Fig. Open Cycle gas turbine

9. Closed gas cycle turbine

Fig. T-S & P-V Diagrams of closed cycle gas turbine
9

10. Basic Components


11. Basic Components

12. Basic Components
•
Compressor
•
•
Combustion Chamber
•
•
Draws in air & compresses it
Fuel pumped in and ignited to burn with
compressed air
Turbine
•
•
Hot gases converted to work
Can drive compressor & external load

13. Basic Components
•
Compressor
•
•
Combustion Chamber
•
•
Draws in air & compresses it
Fuel pumped in and ignited to burn with
compressed air
Turbine
•
•
Hot gases converted to work
Can drive compressor & external load

14. Basic Components
•
Compressor
•
•
Combustion Chamber
•
•
Draws in air & compresses it
Fuel pumped in and ignited to burn with
compressed air
Turbine
•
•
Hot gases converted to work
Can drive compressor & external load

15. Constant volume Gas turbine
Exhaust Gas
Load
Feed Water
To stack
Boiler
Valve V1
Motor
Steam
turbine
Exhaust
Valve V2
Air
Valve V3
Compressor
Fuel Tank

16. GAS TURBINE WITH REGENERATION CYCLE
The thermal efficiency of the Brayton cycle increases as a result of regeneration
since less fuel is used for the same work output.
A gas-turbine engine with regenerator.
T-s diagram of a Brayton
cycle with regeneration.
16

17. Effectiveness
of regenerator
Effectiveness under coldair standard assumptions
Under cold-air
standard assumptions
T-s diagram of a Brayton
cycle with regeneration.
17

18. GAS TURBINE WITH INTERCOOLING CYCLE


19. GAS TURBINE WITH REHEATING CYCLE

20. Brayton cycle with
intercooling, reheating, and
regeneration
For minimizing work input
to compressor and
maximizing work output
from turbine:
A gas-turbine engine with two-stage compression with intercooling, two-stage
expansion with reheating, and regeneration and its T-s diagram.
20

21. 21
Jet-propulsion

 An engine that burns fuel and uses the expanding
exhaust gases to turn a turbine and/or produce thrust
 The concept of thrust is based on the principle of
Newton’s Third Law
In jet engines, the hightemperature and highpressure gases leaving the
turbine are accelerated in a
nozzle to provide thrust.

22. 4.4.1 Principles of jet propulsion

 It is based on Newton's first and third law of motion.
 A jet engine is an engine that discharges a fast moving
jet of fluid to generate thrust in accordance with
Newton's third law of motion.
 An engine that burns fuel and uses the expanding
exhaust gases to turn a turbine and/or produce thrust

23. Types Of Jet engines

•Turbo jets
•Turbo fans
•Ramjets
•Rockets

24. Jet Engine


25. Jet Engine


26. 

27. Turbo jet engines

Working principle
jet engines are also called as gas turbines. The
engine sucks air in at the front with a fan. A
compressor raises the pressure of the air. The
compressed air is then sprayed with fuel and an
electric spark lights the mixture. The burning gases
expand and blast out through the nozzle, at the
back of the engine. As the jets of gas shoot
backward, the engine and the aircraft are thrust
forward.

28. Turboprop engine

Approximately 80 to 90% of the thrust is
produced by the propeller and 10 to 20% of
thrust is produced by jet exit of the exhaust
gases

29. Turboprop engine


30. Ram jet engine


31. Rocket Principles

• Rocket thrust is the reaction force produced by
expelling particles at high velocity from a nozzle
opening.
• High pressure/temperature/velocity exhaust gases
provided through combustion and expansion through
nozzle of suitable fuel and oxidizer mixture.
• A rocket carries both the fuel and oxidizer onboard
the vehicle whereas an air-breather engine takes in
its oxygen supply from the atmosphere.

32. Solid propellant rocket
engine

 In the solid-chemical rocket, the fuel and oxidizer are
intimately mixed together and cast into a solid mass, called
a grain, in the combustion
 The propellant grain is firmly cemented to the inside of the
metal or plastic case, and is usually cast with a hole down the
center. This hole, called the perforation, may be shaped in
various ways, as star, gear, or other more unusual outlines,
The perforation shape and dimension affects the burning rate
or number of pounds of gas generated per second and,
thereby, the thrust of the engine.
 After being ignited by a pyrotechnic device, which is usually
triggered by an electrical impulse, the propellant grain burns
on the entire inside surface of the perforation. The hot
combustion gases pass down the grain and are ejected
through the nozzle to produce thrust.

33. Types of solid propellant

a) Restricted burning

34. a) Restricted burning
 usually in the shape of a
 A restricted-burning charge is
solid cylinder.
 It completely falls the combustion chamber and burns
only on its end.
 The thrust developed is proportional to the cross-sectional
area of the charge
 The restricted-burning charge provides a low thrust and
long burning time.

35. Types of solid propellant
b) Unrestricted burning

 It is essentially free to burn on all surfaces at the
same time
 The restricted burning propellant delivers a small
trust for a relatively long period while unrestricted
type delivers relatively large thrust for short period.
 It’s application is in aircraft rockets, antiaircraft
rockets and boosters etc.

36. Liquid propellant rocket engine


37. Liquid propellant rocket engine

• The common liquid rocket is bipropellant;
it uses two separate propellants, a liquid
fuel and liquid oxidizer
• These are contained in separate tanks and
are mixed only upon injection into the
combustion chamber
• They may be fed to the combustion
chamber by pumps or by pressure in the
tanks