Turbojets The basic idea of the turbojet engine is simple. Air taken in from an opening in the front of the engine is compressed to 3 to 12 times its original pressure in a centrifugal or axial compressor. Fuel is added to the air and burned in a combustion chamber to raise the temperature of the fluid mixture to about 1,100°F to 1,300° F. The resulting hot air is passed through a turbine, which drives the compressor. If the turbine and compressor are efficient, the pressure at the turbine discharge will be nearly twice the atmospheric pressure, and this excess pressure is sent to the nozzle to produce a high-velocity stream of gas which produces a thrust. Substantial increases in thrust can be obtained by employing an afterburner. It is a second combustion chamber positioned after the turbine and before the nozzle.The afterburner increases the temperature of the gas ahead of the nozzle. The result of this increase in temperature is an increase of about 40 percent in thrust at takeoff and a much larger percentage at high speeds once the plane is in the air. The turbojet engine is called a reaction engine. In a reaction engine, expanding gases push hard against the front of the engine. The turbojet sucks in air and compresses or squeezes it. The gases flow through the turbine and make it spin. These gases bounce back and shoot our of the rear of the exhaust, pushing the plane forward. Picture of Turbojet Engine Turbojets The basic idea of the turbojet engine is simple. Air taken in from an opening in the front of the engine is compressed to 3 to 12 times its original pressure in a centrifugal or axial compressor. Fuel is added to the air and burned in a combustion chamber to raise the temperature of the fluid mixture to about 1,100°F to 1,300° F. The resulting hot air is passed through a turbine, which drives the compressor. If the turbine and compressor are efficient, the pressure at the turbine discharge will be nearly twice the atmospheric pressure, and this excess pressure is sent to the nozzle to produce a high-velocity stream of gas which produces a thrust. Substantial increases in thrust can be obtained by employing an afterburner. It is a second combustion chamber positioned after the turbine and before the nozzle.The afterburner increases the temperature of the gas ahead of the nozzle. The result of this increase in temperature is an increase of about 40 percent in thrust at takeoff and a much larger percentage at high speeds once the plane is in the air. The turbojet engine is called a reaction engine. In a reaction engine, expanding gases push hard against the front of the engine. The turbojet sucks in air and compresses or squeezes it. The gases flow through the turbine and make it spin. These gases bounce back and shoot our of the rear of the exhaust, pushing the plane forward.

The basics of a turbofan are relatively simple. There are 4 parts and this is what they do: 1. The compressor which is used to increase the pressure (and temperature) of the inlet air. 2. One or more combustion chambers in which fuel is injected into the high-pressure air as a fine spray and is burned creating heat the air. The temperature in the chamber rises during combustion, so the hot air needs to occupy a larger volume than it did when cold, so it expands through the turbine. 3. The turbine which converts some of this temperature rise to rotational energy. This energy is used to drive the compressor. 4. The exhaust nozzle which accelerates the air using the remainder of the energy added in the combustor, producing a high velocity jet exhaust. See a video of how all this happens courtesy of GE here- http://www.geae.com/education/engines101/

Well that depends on the turbofan. Their are a couple of different kinds. High bypass are the most common but there are low bypass, after burning bypass. Then there are different configurations of the turbofan. Such as single shaft turbofan, Aft fan turbofan, two spool,boosted two spool turbofans, triple spool (this is what Rolls-Royce uses), and then geared fan. All a turbofan really is, is a jet engine that has a large ducted prop that is called N1. They are more fuel efficient and less noisy than a turbojet. You can find several aircraft power plant books that can go into much greater detail. All, well most of the commercial airliners you will fly on now will be powered by turbofans, unless a turbo-prop otherwise.