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.
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
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
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
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.
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.
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
