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Post by racket on Dec 5, 2021 18:56:25 GMT -5
Hi Chris
An atmospheric test would be the way to go , but a lotta work making up the rig , but , if all else fails , it might be the only alternative , I've got my big 65cc backpack blower to feed it :-)
I'll try some "isolation" treatment of the fueling first as its hopefully more simple to construct .
Cheers John
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Post by racket on Dec 5, 2021 18:58:48 GMT -5
Hi Monty
Yep , direct injection , the bent tip produces a fan spray thats reasonably well atomised :-)
Cheers John
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monty
Senior Member
Currently being spanked by mother nature.......
Joined: September 2018
Posts: 400
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Post by monty on Dec 5, 2021 19:34:57 GMT -5
Hi Monty Yep , direct injection , the bent tip produces a fan spray thats reasonably well atomised :-) Cheers John John,
Now I'm almost as excited as your afterburner, or Andy's ignition....
I've been trying to come up with a way to use primary air swirlers like a full size engine. I think I now have the way. I may build an atmospheric test rig just to try it out. Probably a single swirler just to cut down on the cost and size. Plus I want to encase it in a quartz tube so I can make a video.
Monty
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Post by racket on Dec 5, 2021 20:38:54 GMT -5
Hi Monty
Sounds good :-)
I'm making up a "pulse chamber" for my fuel , just a crude vertical bit of tube with the end blocked so that theres an "air chamber", mounted at the engine fuel inlet , any "shock waves" will go straight up the chamber whilst the supply fuel comes in the side of the tee piece .
Worth a try
Cheers John
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dieselguy86
Veteran Member
Joined: September 2014
Posts: 186
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Post by dieselguy86 on Dec 6, 2021 0:01:59 GMT -5
Chris,
What if fuel injection is significantly higher than the pr in the chamber? I'm wanting to use aeromist .012" 1,000psi misting nozzles for injectors. Would this be high enough that any localized events wouldn't affect the flow of the nozzle? I don't know what idle pressure will be, but 100% should be around the 1,000psi mark.
-Joe
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Post by racket on Dec 6, 2021 0:32:55 GMT -5
Hi Joe
I think you'll be OK :-)
Cheers John
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Post by racket on Dec 6, 2021 0:35:23 GMT -5
Hi Guys Pulse chamber fitted , don't know if it'll make any difference , but won't hurt to try :-) I'll do some testing of the fuel system tomorrow to see if its all pressure sealed Cheers John
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Post by racket on Dec 13, 2021 23:56:08 GMT -5
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ripp
Veteran Member
I'm sorry, I don't speak english, so I torment you (and myself) with a translation program,Sorry
Joined: January 2013
Posts: 236
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Post by ripp on Dec 14, 2021 3:46:14 GMT -5
Hi John,
up to 1.7 bar everything seems to be fine.
if you exceed 1.7, you can see red tongues of fire that means for me liquid fuel is burned at the ngv with too little oxygen content.
what's going wrong? what do you suspect?
Cheers Ralph
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Post by racket on Dec 14, 2021 15:39:52 GMT -5
Hi Ralp
LOL........I have no idea whats happening :-(
Generally a bad combustor should have problems at idle when air pressures are low and flows relatively high , but I can idle down to 0.3 bar without problems , at which point the fuel atomisation is relatively poor .
I'll have to put the engine away until after Christmas , too many other jobs to do , will have a think on things over the holidays .
Theres only one more test I can do before pulling the engine apart to see if theres anything I can change inside and thats a test with the dual fuel pumps and using straight kero instead of my "JP3 mix" , the extra pump will provide more than enough fuel and perhaps the straight kero might burn differently , my current fuel with its 2/3rds petrol might be a tad fussy with regards the fuel/air ratio ..........don't know , just gotta keep trying different things to see if they make a difference and if a trend develops .
Cheers John
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miuge
Veteran Member
Joined: March 2014
Posts: 200
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Post by miuge on Dec 14, 2021 16:25:17 GMT -5
Hi John,
Have you checked injector flow pattern (fan, atomization) at higher fuel pressures? The fan looked pretty well atomized with that syringe test, but could that fan narrow down and pour fuel straight into the combustor at higher pressure levels? How high P2 pressures did Andy experiment with? Are the injectors identically shaped with Andy's engine?
Would be interesting to see what's happening inside the engine while running, would it be too much work to add a clear inspection window to see the front end of the combustor - what or when the carbon trails are caused and does it have something to do with the pulsation.
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Post by racket on Dec 14, 2021 18:37:59 GMT -5
The spray pattern tends to get wider with added pressure and the atomisation keeps improving .
At my low idle theres barely 5psi of pressure drop across the injector , but a full power its closer to 50 psi
I've tried injectors bent similar to Andys as well as with less tip bend to narrow the fan angle so that fuel wasn't hiting the wall and causing the high temps on one side of the exhaust.
I might try one more test this afternoon , I've emptied 7 litres of kero into the remaining 10 litres of JP3 , so now I have a mix of ~10 litres Kero to 6 litres of petrol , hopefully I'll see a "trend" change , also I now have an empty 20 ltr kero drum for refilling when I do a straight kero test with the twin fuel pumps .
A clear window would be a "challenge" :-( though very interesting if I could :-)
Cheers John
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Post by wannabebuilderuk on Dec 14, 2021 19:33:07 GMT -5
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bigkwaka
Member
Joined: August 2010
Posts: 11
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Post by bigkwaka on Dec 14, 2021 22:23:57 GMT -5
I remember a video way back of a DIY GT with a viewing window that Chris Krug made. youtu.be/bOXBys8gqOM
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Post by racket on Dec 15, 2021 0:37:26 GMT -5
Hi Guys
Well , this afternoons test with a different fuel mix resulted in the same outcomes as yesterday , guess I can cross off fuel as a cause
Cheers John
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