Gas turbine engine is actually a jet engine. If you visit an airport, have a look at the engines mounted on the aircraft. You will see them hanging under the wings, or fixed to the rear of the fuselage. There may be two,three,or even four engines,depending on the type of air plane. A Boeing 747 jumbo jet, for example, needs four engines.
The jet engine's job is to force as much air out of its exhaust duct as possible so that it will be pushed forwards just as a toy balloon flies across the room when the air rushes out of it. The machinery doing that job is known as the gas turbine.
Gas turbine engine works on the same principle as a steam turbine,water turbines, and wind turbines. Most power plants use coal, natural gas,oil or a nuclear reactor to create steam. The steam runs through a huge multi-stage turbine to spin an output shaft that drives the plant's generator. Hydroelectric dams use water turbines in the same way to generate power. So much water runs to move the turbines. Wind turbines, also known as wind mills,use the wind as their motive force.
A gas turbine is an extension of the same concept. In a gas turbine a pressurized gas spins the turbine, the machinery in the engine is designed to squeeze the air as much as possible before letting it escape out of the exhaust. It then is mixed with something like jet fuel, propane, natural gas or kerosene. It becomes a vapour and is burned. the heat that comes from burning the fuel expands air very rapidly, and the high-speed rush of the hot air rushes out with tremendous energy, it spins the turbine.
The way in which a gas turbine engine works is really quite simple. There are three main parts: Compressor,Combustion chamber and Turbine.
Compressors are the 'heart' of a jet engine. they work like big,powerful pumps,which thoroughly squeeze the air sucked in through the engine intake. The more they squeeze the air, the more efficiently the engine will work.They have many rows of blades attached to the shaft,for example,the engine powers the 180 seat Boeing 757 can produce 37,600 lbs of thrust (it means that the engine can lift the weight 37,600 lbs).The compressor is made up of 12 stages or rows, each stage consisting of a number of blades. Each row of blaces turns the air in the same way as a simple electric fan, and each passes air to the row behind. As the air moves back along the compressor it has less and less space to occupy, so it becomes squeezed, when the air passing through the compressor has been squeezed,it is burned in the combustor.
Combustion chamber or combustor
Air is forced into the combustor,fuel is added,and a continuous torch of burning gases is formed. An igniter starts off the combustion process. during the burning process the mixture of fuel and air expands very rapidly and is forced under enormous pressure out of the chamber. The gas jet is aimed at the turbines,blowing them round so that they can turn the fan and compressors which push the aircraft forwards.
Turbine
It works on the same principle as a windmill which turns when blown by the wind. It is mounted on the same shaft as the compressor,and is blown round by the hot,high-pressure air rushing out of the combustion chamber, and into the exhaust duct,pushing the engine forwards. As the turbine spins so does the compressor and the continuous process will go on.
At the end side of turbine is an output shaft which can be used for other jobs. For example,a shaft can be joined to turn the helicoptor rotor,aircraft propellers etc.
Gas turbine engies are used in marine to power ships,vessells; in industrial plant to power generator,machine,pump,they are also used in the military to power the tank and some racing cars also use gas turbine engine.
Gas turbine engine is an expensive machine. The parts used in making the engine must be extremely strong and very carefully made.The blades of compressors and turbines spin at some 20,000 revolutions per minute and furthermore the turbine must stand up to the heat of 1200C.The consumption of the fuel have no difference between the slow and the fast stage. Therefore the gas turbine engine is not used in the car but it is fit for the long range aircraft.
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