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Post by pitciblackscotland on Jul 28, 2023 22:34:39 GMT -5
Hi John, that doesn't look to bad you can make that work again Cheers, Mark.
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Post by racket on Jul 28, 2023 23:52:53 GMT -5
Hi Mark
LOL......Just a lick of paint required ;-)
Cheers John
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Post by racket on Jul 30, 2023 0:58:40 GMT -5
Hi Guys
Engine pulled apart , some good, some bad.
The compressor wheel is OK , the 1/2"bore tester was a nice sliding fit from both sides , same as original , and the comp was still in its place with alignment marks OK .
The flametube Primary Air swirler tubes are doing their job nicely with the FT front wall relatively cool .
Bearings seem OK .
My outer can appears to have survived the extra air pressure inside .
The bad , a bit of material knocked off a few turb inducer blades , but I think I can set the wheel up in the lathe and grind all the inducers to the same shape to maintain balance.
Flametube was "welded" to the NGV in a few spots where there'd been excessive heat, the molten bits are probably what knocked off the turb inducer corners .
I might need to fit some deflector devices at the outlets of the diffuser to force more air to the inner wall and back to the other bits which look a tad hotter than normal .
A few of the NGV vanes seem to have lost a bit more material .
But I think I can resurrect the beast :-)
A pressure blowoff valve in the fuel line is required , and a "dam wall " fitted near the combustor drain port to catch any fuel thats swirling around the can , there are witness marks indicating this is happening and might have been what caused the excess heat on the NGV/flametube .
Otherwise I'm pretty happy with the outcome of a very severe overspeed , its taught me a lot and should be of help with Andy's engine :-)
Cheers John
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Post by finiteparts on Jul 30, 2023 15:31:37 GMT -5
Any pictures?
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Post by racket on Jul 30, 2023 17:24:39 GMT -5
Hi Chris
I'll take a few this morning :-)
Cheers John
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Post by racket on Jul 30, 2023 17:56:05 GMT -5
Hi Chris A few pics Cheers John
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Post by finiteparts on Jul 30, 2023 18:22:59 GMT -5
Thanks for sharing the pictures.
That area really got hot. Is it isolated to just one area? Like maybe an injector developed a leak and created a hot streak?
Or, one got plugged and pushed more out of the other tubes? That would probably better fit with the increase in fuel pressure...maybe. Seems like if it developed a leak, the fuel pressure would have dropped. hummm...
The thrust bearing was ok? I would think it might have been worked a tad bit hard at those pressures.
Glad it was limited to the small amount of tip damage.
Hopefully, you can find the smoking gun so you don't have any more record setting thrust numbers! Ha!
- Chris
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Post by pitciblackscotland on Jul 30, 2023 18:44:05 GMT -5
Hi John, some of those NGVs looks crispy Do you have enough inconel Cheers, Mark.
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Post by racket on Jul 30, 2023 19:14:47 GMT -5
Hi Chris
Yep , very hot , enough that the air/oxygen coming in acted as a cutting torch on the lip of the NGV and down into the Inconel vanes .
All I can think of is extra fuel from that swirling at the rear of the outer can , but then where did that come from ??
Thrust bearing looks OK , is pretty big :-)
I'm going to need to do some static testing of the fuel injection into the evap tubes , mount the fuel manifold and hook it to the garden hose to see if theres fuel being forced back out .
Lotsa unknowns at this stage , but nice to know that the afterburner is working OK and generating some heat, I'll remove the short section of nozzle that I'd retacked on for the test, open it back up to 140mm to cope with the hotter A/B gases .
I'll give everything a good clean and see what can be done to get it going again :-)
Cheers John
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Post by racket on Jul 30, 2023 19:18:44 GMT -5
Hi Mark
Don't know if I'll redo the NGV vanes , its a huge amount of work , I guess I'll think more about it once some of the other issues are sorted out, the NGV design needs a rethink in light of recent developments :-(
Cheers John
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Post by racket on Aug 2, 2023 20:49:47 GMT -5
Hi Guys Baffles fitted at the rear of the outer to prevent the swirl witness mark "fuel ". Did an insitu water test of the fuel manifold to see if any fuel was back flushing , but nothing noted , so none the wiser Also a water discharge of the manifold to see if all was OK , the usual propane test has been acceptable. So time to start thinking about deflecting baffles at the diffuser outlet to get more air into the inner wall/s and the NGV front face , I didn't add them when I made changes to the Primary air entry with the addition of the tubes so as to not confuse things , but the tubes are working OK so time to add the extra Slowly slowly we're getting there Cheers John
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Post by racket on Aug 16, 2023 1:00:58 GMT -5
Hi Guys
All back together and ready for a testrun soon .
Added the air deflectors and some extra straightening vanes onto the flametube .
Repositioned the ignitor deeper into the flametube as it was a tad marginal .
Added a P2 line pressure switch, after recommendations by Andy M , to switch off power to the fuel pump if P2 goes above my desired max of 3.5 Bar , tested insitu a few times using the workshop air compressor connected to the P2 line , with fuel pump pumping fuel, the fuel pump switched off at 3.65 Bar :-)
Cheers John
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Post by racket on Aug 21, 2023 4:18:37 GMT -5
Hi Guys
Test run yesterday , didn't go to plan :-(
The engine refused to ignite , after just about running my batteries down from several attempts it finally fired up , starter got that hot I needed a leather glove to hold it , strange as I thought the mods I made to getting the ignitor into the flametube would have aided ignition .
Then the P2 pressure switch I fitted to kill the fuel pump and prevent an overspeed decided to activate several psi early than my setting,..... today I rechecked the setting at 3.65 Bar and it was spot on , so now I've increased it to 4 Bar to counter whatever was causing the premature activation .
To finally top off the problems , the A/B fuel pumps didn't produce their normal pressure , instead of ~20 psi it was at only ~15 psi , undoubtedly caused by me having to hastily replace my ancillories battery when I noticed it had "cracked"and was leaking "gel ?? " , the replacement was an old car battery rather than the deep cycle one it replaced .
So today I pulled the engine and started disassembly , the turb wheel still looks OK :-)
I'll complete the strip tomorrow and hopefully won't find anything wrong .
Then I'll need to have a think :-(
Cheers John
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Post by racket on Aug 23, 2023 18:56:55 GMT -5
Hi Guys A friend compiled this for me of the last test run ,..............LOL, one poor ol'fart out of his depth and floundering :-) youtu.be/4Q9YdnLDhEsCheers John
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Post by pitciblackscotland on Aug 23, 2023 21:43:23 GMT -5
Good to see you got your friend with you there John. Looks like that over speed protection device is working.
Cheers, Mark.
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