How jet engin works?

Answer 1

The front fan spins at a high rate to pull in air. Once air is pulled in some of it passes through ducts around the engine core and out the back (high bypass turbofan engine) and a smaller amount of the air is pulled into the engines core. Once in the core it is compressed in stages (gradually gets compressed more and more). Then it enters the combustion chamber where it is mixed with fuel and ignited, then passes into the turbine area where it expands and is propelled out the back. In a high bypass engine as much as 80% of the engines total thrust comes from the air bypassing the core and 20% from the core itself. This engine type is perfect for high flying commercial jets because they are fuel efficient.

The other type of engine is a low bypass turbofan engine. The principal is the same, but 80% of the total engines thrust is coming from the core whereas 20% of the thrust is bypassed. This is a good engine for supersonic aircraft, but most of the energy generated is from the burning of fuel.

Keep in mind that there are many forms of high and low bypass engines each with slightly different fan sized, thrust output, bypass ratios etc.. to achieve an engine that is appropriate for the type of aircraft and its performance requirements.