Presentation on theme: "JET ENGINES. 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 "— Presentation transcript:
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 5.6 SCRamjet
Continued 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
5.1 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. 75% of thrust is produced by the fan.
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
5.6 SCRamjet SCRamjet (Supersonic Combustion Ramjet) A variant of Ramjet Air-breathing jet engine where combustion occurs in supersonic airflow.
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 EngineRockets Oxygen from atmosphere for combustion Carry their own oxygen for combustion Work only in atmosphereWork in vacuum and atmosphere Liquid fuelLiquid or solid fuel High Specific Impulse Low Specific Impulse Complex Structure Simple Structure High EfficiencyLow 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.
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 better 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 type of jet engines is used only in Defence sector. Because it travels at supersonic speed and generally high level of training is required. Since it travels at such a high speed it cannot be used for traveling. That is why turbo-jet engines are very common in use.
13. Future Vision Decreased gross lift – off weight > Smaller facilities & easier handling Leading to higher safety Flights can be aborted, whiles the vehicle glides back to earth Missions can be more flexible Wider range of emergency landing sites for intact abort
14. Bibilograph Harris, William S. Jaeckel, Ernst (DE) engine.com