|
Post by racket on Apr 1, 2022 18:21:27 GMT -5
|
|
|
Post by racket on Apr 1, 2022 16:23:25 GMT -5
|
|
|
Post by racket on Mar 28, 2022 0:50:24 GMT -5
Hi Guys
Well , the NGV has been split ,,,,,,,,,,bugger of a job :-(
But its cleaned up and ready to have the slots for the vanes ground out to remove the remnants of the old vanes .
The exducer shroud and exhaust stub assembly had "sprayed Inco" inside it , some thankfully flaked off when heated with the oxy torch , but enough remained to be a problem , so popped it in the lathe to cleanup ..............duh, didn't work , the bits of molten turbine wheel are kinda hard compared to the shroud material , looks like I'm gunna have to grind them , the clearance between shroud and wheel will hopefully be able to be fudged a bit to resore it to something near what it was before .
Maybe start milling NGV vanes tomorrow ...............one of my favourite jobs :-(
I've ordered some new K type thermocouples , I need to replace the broken off one , but may as well replace both while I'm at it as the remaining one looks a tad "cooked", and a matched pair is a safer option anyway .
Cheers John
|
|
|
Post by racket on Mar 28, 2022 0:38:15 GMT -5
Hi Andy
Looking good :-)
Love shiny stainless bits , its such a shame they don't stay that way for long :-(
Cheers John
|
|
|
Post by racket on Mar 26, 2022 18:00:52 GMT -5
Ebay is the place to go , you'll need a sheathed K type thermocouple for the jetpipe temps and a compatable thermometer , an oil pressure gauge and a P2 gauge as a minimum
|
|
|
Post by racket on Mar 26, 2022 17:55:39 GMT -5
Congratulations :-)
It takes us all a while to know what our engines require , every engine is different .
Looking forward to more
Cheers John
|
|
|
Post by racket on Mar 26, 2022 17:52:03 GMT -5
Yep , cooked turbine wheels don't "taste" very nice :-(
But you can cook an expensive wheel as easily as a cheap one , theres only a few hundred degrees of temp difference , probably better at this stage to stick with the cheap versions and correct the operational parameters .
Do you have a P2 gauge on your engine ??
If you do , then an idle speed this early in your development needs to be ~7-10 psi , this should ensure that the comp is operating at reasonable efficiencies , once you are confident with your engines operation , then and only then , start to reduce idle P2s , but don't go below ~4 psi without a jetnozzle attached , or 5 psi with one , your jetpipe temperature gauge is your best friend at low power settings , temps should be below 600deg C -1100 F , several seconds of higher temps during a spoolup are OK , but be careful of extended spoolups with high temps,...... a fast start is a good start :-)
Cheers John
|
|
|
Post by racket on Mar 24, 2022 23:11:28 GMT -5
Hi Guys Replacement turbine wheel's exducer given a "mild" clipping , back from 25 degrees to 30 degrees rather than the previous 40 degrees , the extra deflection should help with turb power production and less fuel/temps. Exducer throat area increase with the mild clip is only about half that of the 40 degree one , but with more deflection , things will hopefully still workout OK . I'll get the NGV opened up tomorrow :-) Cheers John
|
|
|
Post by racket on Mar 21, 2022 16:32:43 GMT -5
Hi Andy
Nice workmanship on those bits :-)
The engine will be together pretty quickly .
Cheers John
|
|
|
Post by racket on Mar 21, 2022 16:28:48 GMT -5
Hi Ben
Yep , It could be ground down , but theres some nasty cracks in the exducer , by the time it was cleaned up it mightn't be very big :-(
Probably best to stick it on the wall as a reminder not to be so "adventurous" with the fueling .
Cheers John
|
|
|
Post by racket on Mar 21, 2022 3:26:02 GMT -5
Hi Mark
LOL.......I haven't even thought about the job of fixing the NGV , I'm still in the stage of trying to understand why the engine hits a "barrier" at ~2 Bar P2 .
The NGV outlet static pressures have made for some interesting number crunching , it appears as though I'm only getting an ~1.33 PR in the NGV , this is a lot lower than expected , so I've got some thinking to do .
The comp inlet static pressure gauge is indicating nearly a 20 Kpa - 2.9 psi pressure drop at 4:1 PR , that represents a pretty high flow speed into the comp wheel inducer , more calcs tomorrow to workout how much air and where its going , maybe a heap of it out the surge slot, don't know , but I'm having "fun??" exploring all the posibilities .
There was damage done , but I also gathered a lot of info , so taken all round , I think I'm ahead , especially with the flametube , if it survived that , it'll survive anything :-)
Sometimes we've just gotta be "adventurous" and take those extra steps even when we know they could be "unwise" ;-)
Cheers John
|
|
|
Post by racket on Mar 20, 2022 23:25:28 GMT -5
Hi Guys She's pulled apart , some pics Flametube is OK and appears to be working nicely with combustion starting right at the front wall Turbine wheel and NGV are a little worse for the experience Exducer shroud has "accretions" which will hopefully be able to be easily removed and the part reused . After having a chat to Andy M we came to the conclusion that maybe trialing a standard turb wheel without exducer clipping might be worthwhile even if flow is reduced just to see what the extra exducer angle/deflection has on performance . At least I know whats required to be fixed , ................LOL, even if I don't really know how I'm going to achieve it A classic case of over temp/speed with tips being thrown off . Cheers John
|
|
|
Post by racket on Mar 20, 2022 4:24:19 GMT -5
Hi Andy
I think the afterburner trials will be a while away , things don't look good when I examined the turb wheel , bits missing , I think I came up against some "limits" :-(
Thrust was good , but I don't know if I'll get that 250 lbs with the current setup , its as though the turbine stage runs into a power production problem once past a 2 Bar P2 , its requiring temperature rise rather than pressure drop to produce power .
At least the fuel supply issue is sorted :-)
Thankfully I have a spare turbine wheel to use , but I'll need to have a re evaluation of a few things , hopefully the flametube has performed OK , it'll be interesting to see what it looks like tomorrow .
There'll need to be several more viewings of the videos and some number crunching .
Cheers John
|
|
|
Post by racket on Mar 20, 2022 1:57:44 GMT -5
Bummer , sorry to hear that , hope you can resurect things :-)
|
|
|
Post by racket on Mar 20, 2022 1:48:16 GMT -5
|
|