1-how does compressor ,compress the air in jet engine? and 2-what force suck air to jet engin for first?

Question

1-for example, is rotating of compressor relative with compressing?,how?2-before suction of air turbine doesn't rotate so compressor too then compressor doesnt make suction of air,well what force suck air in compressor at first?(in this step the engine is turn off)

Answer 1

A jet engine uses an axial flow compressor - spinning blades pick up air and drive it into the combustion chamber.  The compressor blades are driven by exhaust gas from the jet discharging through a turbine.

http://en.wikipedia.org/wiki/Gas_compres...

When a jet engine is spinning up on the ground, a forced air source called a "Huffer" blows air into the combustion chamber to get the engine going.

Answer 2

1. Yes it is relative.

2. The first blade of the turbine is powered, it pulls the air in first.

3. Then that starts the other blades turning.

4. Each spinning blade compress the air further and further. There are

    many blades in a turbine, and because jet fuel (which is basically high octane diesel ) is combustable under pressure, the fuel is injected in the middle of the turbine. The resulting explosion causes the blades in the rest of the turbine to spin producing thrust.

5. When enough compression is built to explode the fuel, then the first blade ( or fan, if you will ) can be turned off and the engine will run on its own. The speed of the engine is determined by how much fuel is introduced into the combustion chamber.  

Answer 3

There are a lot of variations and options on design and applications of jet engines. The thing to notice is the angle of fan blades and placement of internal obstructions. Consider the oversimplification for a moment, of a tube with a pressure source in the middle, like burning fuel, and a center shaft with a fan on each end inside the tube. One end has blades angled much steeper than the other. The blades turned to offer the least obstruction will get the most gas escaping through them at the best leverage angle to turn the shaft, and the shaft will turn in that direction. This will be a high volume of hot gas, out one end. The turning shaft will turn the other fan, with it's blades angled to grab a small amount of cold air and cram it into the tube under high pressure and low volume. This source of oxygen mixes with injected fuel at the middle, and combustion is maintained. Placement of contoured obstructions inside the tube, the front fan being of large diameter, and other "tuning" results in increased efficiency for various applications. Regards, Larry.

Answer 4

Some air is already in the engine anyway, so simply burning fuel should start the turbine to spin, which will start sucking in more air. Otherwise they probably use an electric starter motor, just like on a car.

For military aircraft, I've been told that sometimes they use gunpower as an explosive to start the engines turning.  I also heard that the Navy has big portable fans on aircraft carriers for forcing air into the engine for a quick jump start.