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Post by racket on May 7, 2024 17:31:43 GMT -5
Thats an extremely small diameter diffuser, I doubt that theres actually much diffusion happening at all other than inefficiently at the dump .
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Post by racket on May 7, 2024 4:02:30 GMT -5
This is getting very confusing :-(
Please provide more info , maybe a rough drawing .
From what I can unravel from your emails , your current comp wheel is sitting too far forward due to its smaller tip height , resulting in the rear wall of the wheel not being within the recess , if this is the case then you could run the engine with this setup as the air exiting the wheel will adjust itself to the larger diffuser height , the air from the wheel will not be impacting a step at the edge of the recess, the extra clearance behind the wheel won't be a problem , the main concern is the clearance between wheel and the shroud.
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Post by racket on May 6, 2024 16:36:01 GMT -5
A larger tip height will change the engine design meaning your diffuser approach angle won't be correct , we can't just make changes to a design and expect it to work
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Post by racket on May 5, 2024 19:07:43 GMT -5
Hi Andy
Good spoolup :-)
What sort of P2 were you running at ??
Was the A/B doing the "machine gunning" or was it you doing multiple ignitions ??
Cheers John
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Post by racket on May 5, 2024 16:55:11 GMT -5
It'll certainly have a bad effect on the engine if the supersonic airflow doesn't transition from the wheel to the diffuser as smoothly as possible, theres a lot of diffusion done in that critical area
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Post by racket on May 3, 2024 20:44:55 GMT -5
Yep , its the recirculation thats important
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Post by racket on May 3, 2024 16:32:17 GMT -5
Hi Soorkie
It might be beneficial for you to build a turbocharger based engine first to gain experience before attempting the much more complex task of building an axial engine , the turbocharge has containment built in , so much safer
Cheers John
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Post by racket on May 3, 2024 16:28:49 GMT -5
I don't think the "vacuum" at the core will make much difference to the flow of air through the flametube wall holes , you're also feeding in a large volume of gaseous fuel , a 1,000 times more volume than liquid fuel .
If you can produce a nice spread gaseous fuel across the flametube , it'll work just fine :-)
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Post by racket on May 2, 2024 16:53:39 GMT -5
What you're proposing is a hollow cone spray nozzle normally used in gas turbines when spraying liquid fuel . Yes it creates recirculation into the "hollow" center of the spray pattern for good flame stability. I guess it'd be a case of getting a large enough flow capacity for gasious injection rather than liquid , but can't see why it wouldn't work :-) I once tried something similar to inject water into the comp scroll of my TV84 engine imgbb.com/hBTkxRL , I made up a swirl chamber that was screwed to the side of the scroll near , the brass plug blocking off the supply hole can be seen in the pic.
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Post by racket on May 2, 2024 16:34:19 GMT -5
Hi Soorkie
To produce a 4:1 pressure ratio you'll be needing to spin the comp to >120,000 rpm , 50,000 rpm will be an idling speed
Cheers John
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Post by racket on Apr 29, 2024 17:05:24 GMT -5
1 lpm is a pretty small amount for a turbo of your size :-(
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Post by racket on Apr 29, 2024 17:01:58 GMT -5
Hi Anders
Now thats one very nice mill :-)
Lotsa handles and knobs, a versatile machine , heh heh , nothing will be beyond you now .
15mm plate , you'll be able to bash things on that without worrying about denting it or bouncing around , I like your vice mounting on the corner , lots more clearance for those awkward jobs .
LOL...you might need a bit more bracing on the new test stand once the beast is at full power ;-)
Cheers John
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Post by racket on Apr 29, 2024 16:49:17 GMT -5
Hi Richard
I did a long time ago and found there was very little from a static rotor when cold even with the 100psi pressure I was feeding the TV84 turbo , but hard to measure with hot oil out of a running engine ;-)
As long as theres design pressure going in , I guess the amount coming out of the turbo is irrelevant, but with all the entrapped air its volume is greatly enhanced.
Cheers John
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Post by racket on Apr 28, 2024 17:24:02 GMT -5
RC Don did some beautiful builds , but ran his engines at modest temps and pressures , hence the modest outcomes
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Post by racket on Apr 27, 2024 17:25:20 GMT -5
Hi Richard
They make some nice stuff :-)
But we really don't need that level of flow control unless we also have variable geometry on the turbine wheel as well to be able to "match" the power requirements of the comp with any degree of efficiency .
Generally, if a turbo has NGVs in the turb scroll , they can be fixed in position once the sweet spot has been determined .
Nice big comp wheel though , had a look at some of their other videos :-)
Cheers John
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