What Is The The Mechanism Of A Jet Engine?

Question

What Is The The Mechanism Of A Jet Engine?

Answer 1

The design of a turbojet is simple.  A series of fans at the front of the engine suck air into the engine and compress it.  Once the air is compressed to high pressure, it is very hot (compression heats the air).  A fine mist of jet fuel is sprayed Into this compressed air, and it ignites and burns with the air.  The resulting exhaust gases, which are extremely hot, rush out the back of the engine.  As they leave the engine, they hit the blades of several turbines (also a kind of fan), and force them to turn.  These turbines are connected to the fans in front, so when the exhaust turns the turbines, they drive the compressor fans.

The engine pushes the airplane forward by shooting hot exhaust gases out the back of the engine.  The forward thrust is just a reaction to the gases rushing out the back.

Modern airliners use turbofans, which are simple variations on this design.  In a turbofan, there's a huge fan in the front of the engine.  This fan is very much like a propeller, only it spins a lot faster, it has far more blades, and it is surrounded by a cowling, which makes it quieter and more efficient at high speed.  The fan sucks air into the front of the engine, and blows most of it right out the back, just like a propeller.  Some of the air goes into the core of the engine, where it meets the same compressor fans, combustion can, and turbines that exist in a traditional jet engine.  The exhaust from this core of the engine also drives the front fan, just as it drives the compressor fans.  Most of the thrust produced by this type of engine comes from the front fan, and only part of it comes from the hot exhaust rushing out the back of the central part of the engine.  Turbofans are quieter and more economical than pure turbojet engines.

Advantages of jet engines include simple design, extremely high reliability, and suitability to high-speed aircraft.  Disadvantages include poor fuel economy (compared to piston engines), noise, lots of waste heat lost out the back, and the need for extremely high-tech materials in construction that can withstand the tremendously high operating temperatures of the engine.

Answer 2

Have a look at this:

Answer 3

The PV cycle of a jet engine is clockwise similar to an IC engine. It begins with compression of gas, fuel burning at constant pressure, expansion thru the turbine that runs the compressor, further expansion thru the nozzle to produce thrust. The fanjet has additional turbine stages to run a fan, which today produces more thrust than the core engine.

Accessories are many: fuel pump, oil pump, barometric fuel control, means to use hot gas for deicing, variable compressor stages with actuators, turbine case cooling to boost efficiency, gear box to run all of the above.

Answer 4

A jet engine sucks in air, compresses it, mixes it with fuel, and ignites the fuel.  The burning fuel produces hot exhaust gasses that escape by way of the exhaust nozzles, in the process turning a turbine that produces the power for the compressor.  There is much more to it.

To get a good understanding of jet engines, do an internet search on "jet aircraft engine."  That will get you lots of information including pictures, diagrams, and animations.  It is really difficult to explain engines without pictures.  So go do that.

Good luck!

Answer 5

Turbines, they are big wheels with fins on them, that are powered by burning gasses