When you go to an airport and see thecommercial jets there, you cant help but notice the hugeengines that power them. Most commercial jets arepowered by turbofan engines, and turbofans are oneexample of a general class of engines called gas turbineengines. They are used in all kinds of unexpected places.For example, many of the Helicopters you see, a lotof Smaller Power Plants and even the M-1 Tank usegas turbines.
Engineering advancements pioneered thedevelopment of gas turbines in the early 1900s,and turbines began to be used for stationaryelectric power generation in the late 1930s.Turbines revolutionized airplanepropulsion in the 1940s, and in the 1990sthrough today have been a popularchoice for new power generation plants.
The early jet engines were designed solely for aircraftpropulsion.However, development was rapid and the rangeof applications has widened to includeships, hovercraft, power stations and industrialinstallations, all of which benefit form the jet enginesinherent qualities of high power, small size and low weight.
The jet engine or, more correctly, the gas turbine is an internal combustion engine which produces power by the controlled burning of fuel. In both the gas turbine and the motor car engine, air is compressed, fuel is added and the mixture is ignited. The resulted hot gas expands rapidly and is used to produce the power. Sir Isaac 17TH century NEWTON
Consists No. of stationary alternatingrotating n stationary blades. This setupreduces VELOCITY n increases thePRESSURE.The pressure gradually builds up as the airpasses thru the compressor stages untill itreaches the combusion system.In Practical, more than one compressorsare used to achieve a high overall pressure.
This is an annular tube(or ring of tubes) made from heatresistant steel, in which fuel n air are mixed and ignited.It is designed to achieve the most efficient combusion ofmixture so that maximum energy is extracted from the fuel.The air from compressors with pressure of 3MPa, passesinto the combusion chamber where it is mixed with thevapourized flue sprayed from the Burners. Once Ignitiontakes place, the igniters are isolated and combustion iscontinuous.
It consists 1 or more stages of alternating stationary nozzles androtating blades.The blades are attached on discs n the discs to the shaft.The nozzles are provided to increase the velocity of the rotatingblades. Gradually the pressure goes on decreasing. The gases, after passing through turbines, arereleased into the atmosphere.
4. Railway engines : The gas turbines have alsoentered in the field of railway engines. The GeneralElectricity Company have successfully built anumber of 4870 HP engines running on the gasturbo electric principle.
5. Electric power generation : Gas turbine power plant is nowbecoming popular. As compared to steam powerstation, the gas turbine power station requires much lesswater. Therefore, it is used at location where water is lessavailable.
i. Simple construction as compared to multi-cylinder piston engines of comparable power.ii. It occupies less space and is lighter in weight, than a reciprocating engine.iii. Much higher speeds can be achieved.iv. No engine vibrations.v. It gives uninterrupted and smooth power supply.vi. The fuel can be burnt over a large mixture strength.vii. Less major over-haults are required frequently.viii. Superior weight to power ratio.
Gas turbine engines have a great power-to-weight ratio compared to reciprocating engines.That is, the amount of power you get out of theengine compared to the weight of the engine itselfis very good.Gas turbine engines are smaller than theirreciprocating counterparts of the same power.
a) Low thrust at take off.b) Quite expensive materials are required for construction.c) Comparatively shorter life of the unit.d) Requires longer strip for take off.e) Huge fuel consumption.f) Gives more noise than a reciprocating engine.
The main disadvantage of gas turbines is that, comparedto a reciprocating engine of the same size, they areexpensive.Because they spin at such high speeds and because of thehigh operating temperatures, designing andmanufacturing gas turbines is a tough problem from boththe engineering and materials standpoint.Gas turbines also tend to use more fuel when they areidling, and they prefer a constant rather than a fluctuatingload.That makes gas turbines great for things liketranscontinental jet aircraft and power plants, but explainswhy you dont have one under the hood of your car.