Jet Engines
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Transcript of Jet Engines
WELCOME TO JET ENGINES
By:
Jayashree.P
Contents
1. History of Jet Engines
2. Introduction
3. Parts Of Jet Engine
4. How A Jet Engine works
5. Types Of Jet Engine 5.1 Ramjet 5.2 Turbojet 5.3 Turbofan 5.4 Turboprop 5.5 Turboshaft
Continued . . .
6. Comparison Of Turbojets
7. Jet Engine Vs Rockets
8. Difficulties
9. Suggestion For Improvement
10. Merits And Demerits
11. Jet Engine Uses
12. Conclusion
13. Future Vision
14. References
1.History Of Jet Engines
The first jet engine was built by Egyptian scientists during 100 B.C
These device was know as Aeolipile.
Dr. Hans von Ohain and Sir Frank Whittle were the main developers.
2.Introduction
• Jet engine is nothing but a Gas turbine.
• It works under the principle of Newton’s third law
• It states that “For every acting force there is an equal and opposite force”.
• Gas turbine operates like toy balloon
3.Parts Of Jet Engine
FAN COMPRESSOR COMBUSTOR TURBINE MIXER NOZZLE
4.How A Jet Engine Works ?
Jet engines move the airplane forward with a great force that is produced by a tremendous thrust and causes the plane to fly very fast.
Continued . . .
Air Intake
sucked in by the compressor
Compressor
series of vanes and stators. The vanes rotate, while the
stator remains stationary. compressor speed and
temperature increases gradually
Fuel Burner
Fuel is mixed with the air, and electric sparks light the air, causing it to combust.
Combustion Chamber
The air is burnt.
Increase in the temperature of the air, thus increases the pressure inside the engine.
Continued . . .
Turbine
Works like a windmill The blades gain energy from the
hot gases moving past them. This movement is used to power
the compressor.
Jet Pipe and Propelling Nozzle
The hot air rushes out of the nozzle. high pressure Hot air rushes out at very high
speed
5. Types Of Jet Engines
• Ramjet • Turbojet• Turbofan• Turboprop• Turbo shaft
5.1 Ramjet
•It has no moving parts.
• Its compression ratio depends on forward speed.
•It has no static thrust • guided-missile systems, Space vehicles use this type of jet
5.2 Turbojet
•The turbojet engine is a reaction engine.
•Substantial increases in thrust can be obtained by employing an afterburner
5.3 Turbofan
•The objective of this sort of bypass system is to increase thrust without increasing fuel consumption.
•It achieves this by increasing the total air-mass flow and reducing the velocity within the same total energy supply.
5.4 Turboprop
•A turboprop engine is a jet engine attached to a propeller. . •Modern turboprop engines are equipped with propellers that have a smaller diameter but a larger number of blades for efficient operation at much higher flight speeds
5.5 Turboshaft
It does not drive a propeller.
it provides power for a helicopter rotor.
It permits the rotor speed to be kept constant even when the speed of the generator is varied
6. Comparison With Turbojets
Turbojet
Has got compressor, turbine Heavy Mach no. < 2 Starts with zero initial velocity
Ramjets
No compressor, turbine Light in weight Mach no 2 to 5 Start only at Mach 2 and above
7. Jet Engines Vs Rockets
Jet Engine Rockets
Oxygen from atmosphere for combustion
Carry their own oxygen for combustion
Work only in atmosphere Work in vacuum and atmosphere
Liquid fuel liquid or solid fuel
High Specific Impulse Low Specific Impulse
Complex Structure Simple Structure
High Efficiency Low Efficiency
9. Difficulties
Time scale of combustion Total temperature in combustion chamber Coupling the air frame to the engine Scramjet cannot operate below mach 4
9. Suggestion For Improvement
Employ active cooling
Designing better materials and alloys which retain their strength at high temperatures
Smart structures – Structure and material which change their shapes and properties in flight.
Design engines which switch from scramjets to ramjets.
10. Merits And Demerits
Merits of Jet engine over IC engine
Mechanical efficiency of jet engine is high as compared to IC engine.
Weight and speed of jet engine per HP developed is higher than IC engine.
Ignition and lubricating systems are much simpler in jet engine than IC engine.
•Thermal efficiency of Jet engine is low compared to IC engine
•Difficult to start
•Turbine blades need a special cooling system due high temperature
Demerits Of Jet Engines Over IC engine
11. Jet Engine Uses
The industry they’re most prominent in is in the transport industry, where they are used to propel aircraft, boats, and in some one of creations such as a turbojet powered truck.
The first use of the jet engine was to power military aircraft.
The Bell P-59A Airacomet was also developed by the Americans. They had a massive advantage over propeller driven planes, in that they were much faster
The General electric company used a “turboprop” jet engine to run an electric generator.
The jet engine is not only used on aircraft but on boats, where water jets are used to propel the boat forward..
12.Conclusion
Normal type of jet engine is used for domestic purpose i.e. Traveling, carrying goods etc.
Ram and scram type of jet engines used in only in Defence sector. Because it travels at supersonic speed and generally high level of training is required.
Since it travels at such a speed it is can not used for traveling.
So that common type of jet engines are very common in use.
13. Future Vision
Decreased gross lift – off weight> Smaller facilities & easier handling
Leading to higher safetyFlights can be aborted, whiles the vehicle glides back to earthMissions can be more flexibleWider range of emergency landing sites for intact abort
14. Bibilograph
http://www.freepatentsonline.com Harris, William S.
http://www.freepatentsonline.com Jaeckel, Ernst (DE)
http:// www.google.com
http:// www.boeing.com
http:// www.jet engine.com
Thank You