This engine was in a museum in Berlin. It reminds me that I have forgotten most of the things I ever learned in engineering. So I've looked it up again. Roughly, the blades at the front compress the air coming into the engine. Fuel is burned in the middle part which sharply heats the air causing it to expand. The expanding air has to go somewhere so it then passes through a turbine. The turbine actually drives the compressor which makes you wonder how you start the whole process in the first process. Then the expanding air passes through a nozzle. This hot expanding air has a higher velocity than the cold air going in. Hence there is a change in momentum and thus an impulse. By Newton's Third Law, there is a reaction to the force pushing the air backwards and this reaction force pushes the plane forwards. Technically the engine shown is a turbojet rather than a turbofan. Clearly since the engine uses air, you can't use jet engines in space. Rocket motors are different.
