62.Introduction Jet engine is nothing but a Gas turbine. It works under the principle of Newton’s third lawIt states that “For every acting force there is an equal and opposite force”.Gas turbine operates like toy balloon
73.Parts Of Jet EngineFANCOMPRESSORCOMBUSTORTURBINEMIXERNOZZLE
84.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.
9Continued . . . Fuel Burner Air Intake Compressor Combustion Chamber Sucked in by the compressorCompressorSeries of vanes and stators.The vanes rotate, while the stator remains stationary.Compressor speed and temperature increases graduallyFuel BurnerFuel is mixed with the air, and electric sparks light the air, causing it to combust.Combustion ChamberThe air is burnt.Increase in the temperature of the air, thus increases the pressure inside the engine.
10Continued . . . Turbine Jet Pipe and Propelling Nozzle Works like a windmillThe blades gain energy from the hot gases moving past them.This movement is used to power the compressor.Jet Pipe and Propelling NozzleThe hot air rushes out of the nozzle.High pressureHot air rushes out at very high speed
115. Types Of Jet EnginesRamjetTurbojetTurbofanTurbopropTurbo shaft
125.1 Ramjet It has no moving parts. Its compression ratio depends on forward speed.It has no static thrustGuided-missile systems, Space vehicles use this type of jet
135.2 Turbojet The turbojet engine is a reaction engine. Substantial increases in thrust can be obtained by employing an afterburner
145.3 TurbofanThe 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.
155.4 TurbopropA 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
165.5 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
175.6 SCRamjet SCRamjet (Supersonic Combustion Ramjet) A variant of Ramjet Air-breathing jet enginewhere combustion occurs in supersonic airflow.
186. Comparison With Turbojets RamjetsNo compressor, turbineLight in weightMach no 2 to 5Start only at Mach 2 and aboveHas got compressor, turbineHeavyMach no. < 2Starts with zero initial velocity
197. Jet Engines Vs Rockets Jet Engine Rockets Oxygen from atmosphere for combustionCarry their own oxygen for combustionWork only in atmosphereWork in vacuum and atmosphereLiquid fuelLiquid or solid fuelHigh Specific ImpulseLow Specific ImpulseComplex StructureSimple StructureHigh EfficiencyLow Efficiency
209. Difficulties Time scale of combustion Total temperature in combustion chamberCoupling the air frame to the engineScramjet cannot operate below mach 4
219. Suggestion For Improvement Employ active coolingDesigning better materials and alloys which retain their strength at high temperaturesSmart structures – Structure and material which change their shapes and properties in flight.
2210. Merits And Demerits Merits of Jet engine over IC engine Demerits Of Jet Engines Over IC engineMerits of Jet engine over IC engineMechanical 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 engineDifficult to startTurbine blades need a special cooling system due high temperature
2311. Jet Engine UsesThe 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 fasterThe 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..
2412.ConclusionNormal 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.
2513. Future Vision Decreased gross lift – off weight > Smaller facilities & easier handlingLeading 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
2614. BibilographHarris, William S. Jaeckel, Ernst (DE) engine.com