Working of Jet Engine

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 The gas turbine engine is essentially a heat engine using air as a working fluid to provide thrust. To achieve this, the air passing through the engine has to be accelerated; this means that the velocity or kinetic energy of the air is increased. To obtain this increase, the pressure energy is first of all increased, followed by the addition of heat energy, before final conversion back to kinetic Energy in the form of a high velocity jet flux.
Jet engine moves the airplane forward with a great force that is produced by a tremendous thrust and causes the plane to fly very fast.

HOW THE JET ENGINE WORKS?

WORKING CYCLE

The working cycle of the gas turbine engine is similar to that of the four-stroke piston engine. However, in the gas turbine engine, combustion occurs at a constant pressure, whereas in the piston engine it occurs at a constant volume. Both engine cycles  show that in each instance there is induction, compression, combustion and exhaust. These processes are intermittent in the case of the
piston engine while they occur continuously in case of the gas turbine. In the piston engine only one stroke is utilized in the production of power, the others being involved in the charging, compressing and exhausting of the working fluid. In contrast, the turbine engine eliminates the three ’idle’ strokes, thus enabling more fuel to be burnt in a shorter time; hence it produces a greater power output for a given size of engine.

PRINCIPLE

ALL jet engines(also called  gas turbines),work on the same principle. The engine sucks the air in from front through a fan. A compressor raises the pressure of the air .The compressor is made up of fans with many blades and attached to the shaft. The blades compress the air. The compressed air is then sprayed with fuel and an electric spark lights the mixture. The burning gases expand and blasts out through the nozzle,from the back of the engine. As with the flown of the jets of the gases backward the engine and hence aircraft thrust forward.

HOW AIR FLOWS THROUGH THE ENGINE?

The air that enters from the fan goes through the core of the engine as well as around the core.This causes some of the air to be very hot and some to be cooler.The cooler air then mixes with the hot air at the engine exit area.Basically it works on Sir Issac Newton’s third Law of motion: for every action there is equal and opposite reaction.The reaction in this case is thrust(that is produced from engine).In simple terms,this law is demonstrated by releasing an inflated ballon and watching the escaping air propel the ballon in opposite direction.In basic turbojet engine,air enters the front intake and is compressed,then forced into combustion chambers.These gases exerts equal force in all directions,providing forward thrust as they escape from the rear.As the gases leave the engine they pass through a fan like set of blades(turbine) which rotates the turbine shaft.This shaft in turn, rotates the compressor,thereby bringing in a fresh supply of air through the intake.
Engine thrust may be incresed by addition of the afterburner section in which extra fuel is sprayed into the exhausting gases which burn to give the desired thrust.

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