“Air is blown against the pink/Power blades, this spins up the inside turbine, (in real life it’s usually an electric motor.Connected to the Power turbine are the Compression blades, these spin up as well and compress the air into the combustion chamber.”//Gerry Hamilton
source/image: Gerry Hamilton
When the air is compressed enough “Fuel” is added and ignited. This burns and expands, forcing the power turbine to go faster. The burning air/fuel also hit the “Exhaust” blades; these spin the “Intake” blades which push air onto the “Intake” blades, which pushes air into the “Compression” blades.
Once the jet is running the “Start” is turned off.This turns the whole thing around and on the end of the shaft is the BIG fan you see when you walk out to your aircraft.
The reasons the two fans go in different directions are to cancel out the torque.If they both went in the same direction they would have to push against something to turn, and that would twist the engine off the wing.