# Acceleration of gas turbine?

1. Mar 17, 2015

### Almunthir

Hi
I am new member ( mechanical engineer student ) , and the college just add a new course which is
Turbo machinery , any way the teacher is new to the course & the quality of our teacher is not that
good so , I was having a question and ask him but didnt get much from him so here I am ^^

When the plane is taking off the plane start to accelerate and that force come from the thrust when air
flow out through nozzle , so how the pilot increase the speed its got the same intake area so how its
can produce more thrust is it by adding more fuel in combustion chamber or does the area of nozzle
change ?

I wish I didn't bother with my question please help me to understand in easy language ( my main is Arabic )

thanks ^^

2. Mar 18, 2015

### SteamKing

Staff Emeritus
No, you get more thrust from a gas turbine by burning more fuel. That's what the throttle control is for.

3. Mar 19, 2015

### Almunthir

So you mean more fuel then more heat ,so the gas will expand and large in volume and go out of nozzle faster creating more thrust , Am I write ?

And thnx for reply wish all the best for you ^^

4. Mar 19, 2015

### SteamKing

Staff Emeritus
Yes, you are right.

5. Mar 19, 2015

### rcgldr

As more fuel is added, the turbine spins faster, increasing both the intake flow and the exhaust flow.

6. Apr 29, 2015

### Almunthir

Im back again with more question , for sure its about turbojet engine
1* does the combustion chamber increase the pressure or change it due to fuel addition and ignition or its only to add velocity to the compressed air ?
2* also the thrust force that we get is from the nozzle or the turbine ?

thanks

7. Apr 29, 2015

### SteamKing

Staff Emeritus
The Brayton cycle is used to analyze gas turbines:

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

1) The combustion chamber is open at both ends when fuel is injected and burned, so it's a constant-pressure process. The compressor at the front of the engine is the device which compresses the intake air before it enters the combustion chamber.