how do jet engines work?

Question

if the turbine propels the compressor then how does the compressor start

Answer 1

The compressor shoves a bunch of air into the combustion section along with some fuel. Ignite the mixture. Hot gasses expand and the only place for them to go is out through the turbine. A shaft connects the turbine to the compressor to keep the air coming and as long as you feed it fuel, it keeps going.

What gets the whole thing spinning in the first place? Electric motors, hydraulic pressure, gas pressure, pretty much any source of mechanical energy that the designer cares to use.

Answer 2

When the plane is ready to be started, you'll see a portable generator connected to the plane by cables.
The generator is started and supplies power to the starter motor of the plane.
This rotates the whole engine including the compressor.
At a certain number of rpm of the engine, the compressor is putting out sufficient air pressure to feed the combustion chambers of the Jet.
When this is attained and stablised, the fuel injection to the combustion chamber is initiated and ignition supplied.
The fuel (vaporised by the combustion chamber burner), ignites and heats up the air supplied by the compressor. (Some of this air is used as the primary and secondary combustion air).
The heat of combustion (Thermal Energy) added to the remaining air causes high expansion of the air and combustion gases (at about 800°C). This is being fed to the 'Compressor Turbine' which drives the compressor. As fuel is increased, the increased thermal energy and further expansion of the air increases the turbine and compressor speed and, at a specific speed, the engine becomes self sustaining and no longer needs the external power to the starter.
At this speed, the starter is tripped out, the external power is disconnected, the engine(s) fuel and therefore its speed, is increased, the exhaust thrust increases and the plane begins, on instructions from the tower, to taxi to the take off runway.
Engine speed is the further increased, thrust is therefore increased and ...Into the wide, blue yonder goes the Jet.

Answer 3

I think it forces the air to come into the tube to compress the air and the fuel powers the compressor as well.