## Thrust Augmentor Calculation Help

Moderator: Mike Everman

grant_gibson45
Posts: 4
Joined: Sun Mar 02, 2008 2:31 pm

### Thrust Augmentor Calculation Help

Hi,
I am new to the forum, although I have read many of the posts on here, and I know the subject of thrust augmentors comes up quite alot. However I need help fairly soon as I am writing up my university dissertation.

I have dimensions of a converging-diverging augmentor however I have 2 main questions.

How can I predict the thrust increase obtained from the augmentor because I tried working from first principles assuming 1-D isentropic flow, but I don't know the temperature of exhaust gas and velocity at exhaust exit to calculate mach no.

Secondly, I have devised an experiment to investigate the optimum distance from the exhaust tip to the throat of the augmentor and I am supposed to say that students would measure peak thrust against distance from exhaust tip to the throat of the augmentor. Then compare the results they got with a theoretical calculation. But can this "optimum" distance be calculated theoretically ? Is there in fact an optimum distance or am I missing something here.

I really hope someone can help as I am stuck at this point in my write up, because I obviously need to know the maximum thrust output to safely design a clamp.

Cheers

Grant

Al Belli
Posts: 557
Joined: Thu Oct 09, 2003 10:36 pm
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Location: Pennsylvania - USA

### Augmentors

Hi,

See Bruno's post on thrust augmentors in the FAQ section of this site.

You can expect 1.8 to 2 times thrust augmentation.

Al Belli