OLYMPUS AMT Combustor size

[eira]

Hi all,
my name is Eira, new member. I want to built a "mini turbojet" referring to Olympus AMT Netherland.
Does anyone know what is dimension of Olympus combustion chamber (inner diameter x outer diameter x length) ?

thankl you very much.

Regards,
Eira

[racket]

Hi Eira

The actual size of your flametube can be whatever you like if building your own design .

Are you using Olympus parts..........compressor /turbine/shaft ??

The Olympus OD is 131mm so the ID will be say 130mm ,as a rough guess , flametube probably 110-115mm OD , length could be anywhere between 80 and 100mm long, ID probably ~35mm or whatever size is required so as to provide a flametube cross sectional area of ~3 times compressor inducer area .

Cheers
John

[eira]

Hi John,
yes, I use: shaft, turbine, compressor, and NGV of Olympus.
Thank you very much for your information.

Regards,
Eira

[eira]

Hi all,
how about dimension tolerance of turbojet parts so that the parts fabrication not so expensive but meet precision requirement?

thank you very much.

regards,
eira

[racket]

Hi Eira

The various components will have differing tolerance requirements , its too broad a field to be able to provide a simple answer .

Your Schrekling book would give a rough guide to requirements


Cheers
John

[eira]

Hi John,
is it correct for:
1. rotor shaft: diametral tolerance +0.01 mm / - 0 mm
2. compressor wheel to compressor casing gap: 1 mm
3. bearing inner race to shaft : press fit
4. bearing outer race to shaft housing: press fit
5. turbine blade tip to turbine casing: 0.5 mm
6. turbine casing inner diameter tolerance: +0.01 mm/ - 0 mm
7. casing inner diamter tolerance: +0.01 mm/ - 0 mm

Thank you very much.
Regards,
Eira

[racket]

Hi Eira

Tolerances will be dependent on a number of factors , I can't provide an answer to your questions, its far too complex .

As for comp wheel to housing clearances ........1.0 mm is far too great , something closer to 0.1mm for a small engine would be more appropriate ,I use ~0.3mm for my larger engines between comp wheel and front cover shroud .

Unless you have a good grasp of general engineering requirements , I'd suggest you copy a design where all the tolerances have been worked out for you as the engines very survival depends on it being constructed correctly down to the last detail .

If you obtain a copy of Thomas Kamps book Model Gas Turbines , it has scaling data in it to help you "design" your own engine relative to his design in the book .

Cheers
John

[eira]

Thank you very much John.

regards,
Eira

[racket]

Hi Eira

Maybe shift your last Email to this Thread .

Cheers
John

[racket]

Hi Eira

Have you considered joining the GTBA..... www.gtba.co.uk/ they have a lot more expertise with smaller micro engines, I feel it would be well worth the modest cost involved to obtain the best advice, especially when it comes to setting up the bearings, preload sand lubrication , if there are any shortcomings with these critical components you'll very quickly wreck your engine .

Cheers
John