building a jet engine from a turbo-charger(design update)

[vineeth]

Hi.. friends i have updated my combustor and FT design  
please do comment on it if there is any changes to do....



in this above analysis i have reduced FT-dia to 4.5inch and casing dia 6inch (as im using only propane)


primary zone pitch -60mm
secondary zone pitch-140mm
tertiary zone pitch -250mm
converging section -90mm length



turbine scroll inlet - combustor connecting plate.



thanks in advance...

[racket]

Not enough Secondary and Tertiary holes , in an earlier email I advised leaving them the same size and number

[vineeth]

hey john sorry for using the bigger diameter holes i have redesigned it as per my first design now have a look...
5*30 holes
6.2*13 holes
12.5*8 holes



thanks alot john..

[racket]

That should be OK

[vineeth]

Hii guys ... the gap between the convergent nozzle of flame tube and combustor end plate need to be air tight sealed or just need to butt

If you have any images please share 😊
Thanks in advance

[racket]

Due to the differential amount of axial expansion between the "hot" stainless steel flametube and the "cooler" outer can, there needs to be a "rattly" slipjoint at the outlet end of the flametube , there can be several millimeters of movement , I generally use a fairly thick flange on the scroll "foot" , at least 1/2" thick to prevent warping , and use this thickness for the flametube outlet snout to "slip" inside of.
jetandturbineowners.proboards.com/attachment/download/68

[vineeth]

Hii John
What must be the area ratio from compressor outlet to the combustor air inlet ??

[racket]

More info please as I can't workout what you are asking .

[vineeth]

Hii John I have uploaded an image have a look


ibb.co/VQqpdnn

[racket]

Area ratio will depend on which end of the combustor the delivery tube discharges at, if at the Primary Zone end we need to minimise the possibilities of forcing air into only one side of the flametube and blowing the flame to the opposite side, if delivered to the Tertiary end, which is my prefered option, and it is discharged into a plenum surrounding the flametubes outlet "funnel", then there are less stringent requirements .

If you are considering the Primary Zone end then I'd advise against it no matter how big the area ratio used , at the Tertiary end you may only need a 2:1 ratio of outlet to tube area , its more about providing a smooth flow with limited restrictions and sharp turns ...............the best idea is to checkout some pics of the Allison 250 engines combustor which has 2 minimally sized delivery tubes disharging into very large plenums one each side of the combustor

[vineeth]

Thanks John that’s a great piece of info I’ll update my progress in building that air inlet manifold
If anyone had done this manifold before please do share me ur build pics
Thanks in advance

[vineeth]

Hii John I have done a 3D model of air inlet system...just an idea please comment on it
I’m planning to connect those two input pipes to an manifold where it will be connected as one single pipe extend to connect compressor outlet....
I have pinned images below:
ibb.co/VJ69XRr
ibb.co/R2ZytBr

[racket]

No no no , too complicated , too many losses , keep it simple .

My 2 shaft kart air plumbing............. jetandturbineowners.proboards.com/thread/40/2-shaft-turbine-kart-build?page=3

and the GT6041 engines jetandturbineowners.proboards.com/thread/78/garrett-gt6041-powered-kart?page=6

Plumb the air to the outlet end of the combustor .

[vineeth]

Yes John I’ll follow your design again thanks for the help
And I had a doubt ...if the air hits the tertiary zone first will it cause any combustion issues because In Allison engine the air inlet was at the primary zone ..
Please Correct me if I’m wrong

[racket]

The Allison combustor outer can www.google.com/search?q=allison+250+combustor&rlz=1C1CHBF_en-GBAU828AU828&sxsrf=ACYBGNSfFImmhTOLW6VZvdQS1Ivx6WYsSQ:1568006966415&source=lnms&tbm=isch&sa=X&ved=0ahUKEwic-PORgcPkAhXU63MBHZDpDKAQ_AUIEigB&biw=1920&bih=937#imgrc=3g4Etgj0MDDjfM: feeds air to very large plenums which have a baffle inside that helps to distribute air to all Zones ............the value of looking at the Allison can is to see how "flowing" the ducting is , and how it distributes the air , we aren't able to replicate it with our limited means , but simply to use it as a reference, .................no sharp bends and lotsa diffusion at the can .

The turbo generally has comp housing outlets sized to provide reasonable air velocities for flowing air axially along its downstream plumbing , but we need to turn the direction fairly suddenly at the combustor wall , so there needs to be a reduction in velocity from an increase in area to minimise losses , with a poorly designed junction between delivery tube and combustor it is possible to produce sufficient "backpressure" to send the comp into surge .