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Post by aquaticharpy on Sept 23, 2020 11:11:02 GMT -5
Why are the endcaps usually made of super thick flange steel? What would happen if I just welded on some 16ga stainless endcaps? Would that work, I'm a little confused
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slittlewing
Senior Member
Joined: November 2017
Posts: 458
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Post by slittlewing on Sept 23, 2020 16:42:22 GMT -5
In a cylinder or sphere, pressure puts the walls in tension (imagine trying to pull apart a sheet of 1mm steel). On a flat plate the force is subjected more as a “bending” load (try bending 1mm steel, it’s easy). Flat ends are a bad choice for pressure vessels but a lot of them for the sake of simple manufacture in our turbine combustors. That’s why if you look at any normal pressure vessel (fire extinguisher, gas cylinder, boilers, steam engine, autoclave) they are always cylindrical with domed ends rather than flat boxes.
There’s plenty of information and equations if you internet search for “flat head pressure vessel”
The problem is worse when you add heat which softens the material. I had a 3mm thick steel flat top cap visibly balloon a bit after running red hot at just 2bar. My 5mm turbo flange at opposite end (temps about 800C) bulged slightly and gave sealing problems, requiring sealing paste.
Cheers
Scott
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Post by aquaticharpy on Sept 23, 2020 18:05:21 GMT -5
Ah.. so a large thick steel plate is needed to stay while a thin cap would begin to push out. Would the 16ga stainless work to bolt a 2in disc of mild steel to? What should I look for in a turbo flange and how would I attach that to the other side?
Thanks
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Post by aquaticharpy on Sept 24, 2020 8:23:43 GMT -5
Would welding a few sheets of stainless together make a decent flange?
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Post by wannabebuilderuk on Sept 24, 2020 8:59:39 GMT -5
Better going for 5mm+ sheet/disk, fuel inlet cap say 7mm and turbo inlet cap say 10mm
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Post by aquaticharpy on Sept 24, 2020 10:25:06 GMT -5
My fuel nozzle will screw in by the plug, I can weld 3 sheets of stainless to get 6mm thick that should do it? Flanges are hella expensive
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Post by wannabebuilderuk on Sept 24, 2020 13:17:25 GMT -5
Welding three disks won't work as they'll not be joined in the centre, only the edges. What size is your combustion chamber
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Post by aquaticharpy on Sept 25, 2020 23:56:12 GMT -5
It's around 8 inches diameter. Flame tube around 6
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Post by wannabebuilderuk on Sept 26, 2020 5:25:25 GMT -5
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Post by aquaticharpy on Feb 4, 2021 12:32:44 GMT -5
After hours of welding, crying, melting brass nozzles, breaking taps and bending tube, I have a completed jet engine.
I melted my brass nozzle, bought a new HAGO Stainless nozzle and tapped it in, 1/4 brake line for everything, exhaust and oil temp guages, fuel and oil pressure guages. Im using a ProCon Pump for fuel, 250psi rated for about anything, its magic. Oil has a Shurflo. Tonight I fill the tanks start the leafblower and see what happens. Im excited and will try to get some video for you guys. If it runs Ill weld up a frame so its less rednecky.
Fingers crossed!
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Post by aquaticharpy on Feb 11, 2021 10:25:49 GMT -5
I ended up doing fuel and oil lines wrong, so a few messy hours, and 60 psi to the turbo, for some reason my 250 psi Procon Pump wont push my diesel that hard, the 1/3hp motor starts to cut out and stop. Possibly wrong wiring.
Aside from that, my 2 stroke leaf blower isnt blowing hard enough to spool my turbo. Any ideas?
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Post by wannabebuilderuk on Feb 11, 2021 11:49:41 GMT -5
Have you build an adaptor to fit the blower nozzle snug against the inlet? It's not just the volume of air but pressure we need to spin it up with a leaf blower.
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Post by aquaticharpy on Feb 11, 2021 16:45:49 GMT -5
Its already pretty much an equal diameter, Ill see what I can do to hold it on better, problem is this leaf blower wants to propel itself, you gotta be holding it on good or itll slide off one way or another. You set it down and itll keep going
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Post by wannabebuilderuk on Feb 12, 2021 3:58:38 GMT -5
Its already pretty much an equal diameter, Ill see what I can do to hold it on better, problem is this leaf blower wants to propel itself, you gotta be holding it on good or itll slide off one way or another. You set it down and itll keep going That might be the problem, have you got any photos of it. You want the blower to be producing volume and pressure but not velocity so if the nozzle is restricting then the air is being accelerated and thus not producing pressure. Basically if the nozzle is a long two part you want to remove the front part.
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Post by aquaticharpy on Mar 18, 2021 12:24:48 GMT -5
The turbo opening is too big for my leaf blower. Currently Im having issues with fuel and oil.. Stupid venturi effect with tiny line and big Ts.. ll try making a rubber seal on the turbo though
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