Back again..!... The GT6041 powered "Green Beast"..!

[smithy1]

Hi John,

Sorry for the late reply, I've been away for a few days and my lower back has been giving me plenty of grief over the last few days, (getting old sucks)..I'll get the info you need asap. I'll take a photo for you to go with the numbers.

The "anti-surge" slot must be working on the 6041, I've not heard/felt a surge out of it to be honest, even on a solid accel from low rpms, she accelerates easily and runs very well in the mid-range rpms.....You've obviously seen how she runs up at high P2, ~@40-42 psi, she's indeed beast and I still get a silly grin on my head every time I do and engine run...hopefully the people watching enjoy it too...I suspect they do since plenty of them always ask when the next engine run is.

I'm going to be doing a car show/exhibition up at the Bathurst 12hour race this coming Saturday....and on Sunday I'll be doing the Illawarra car show down at Berkley. She's earning her keep....and keeping me busy. All seems well after the rebuild, no oil leaks or vibrations, so I can't complain. I do have one of those niggly tiny little fuel leaks at one of the fuel pumps under/behind the seat, but it's nothing serious, just annoying, I'll get it sorted eventually.

Next week I'm going to see about getting the bodywork "professionally wrapped", the current wrap/covering is not well, it's just a vinyl contact and the sun has not been kind to it, although...it has been on there for a couple of years... and it was free, my son did it for me so I can't complain.

Cheers,
Smithy.

[racket]

Hi Smithy

Thanks for that .

LOL............getting old certainly isn't for wimps ;-)

I did get the 6041's slot to work once when during a start the combustor "back fired" due to too much LPG , the resulting pressure wave blew the bellmouth assembly out of the housing , but normally she's got a very wide map , the 12 bladed comp , plenty of backsweep on the exducer, MWE slot and vaneless diffuser all contribute , it seems once we start using a vaned diffuser and design for PRs of 3.5 and above we start to run into potential problems .

On the C30 compressors at work , have you seen a "slot" for its bleed ??

From what I've been reading the slot needs to be at the inducer throat area , but from pics on the Web , I'm not sure thats how the turbos are being setup , but then again their slots aren't only for surge control but also to bypass the inducer throat flow and provide more air at high pressure ratios/flows...............lotsa things to consider , don't want to stuff it up .

A busy weekend coming up for you, its gunna be hot , keep up the hydration :-)

Cheers
John

[smithy1]

OK...I've had a quick loo at my 6041...from the "primary blades" to the "secondary blades" is 14.2mm, the "slot" is essentially equidistant between the blades, it measures 4.1mm across the slot.




As can be seen in the pic, the "anti-surge" slot just feeds into the inlet slot further forward. Yes, the C30 has a similar setup.

Hope this helps.

Smithy.

[racket]

Hi Smithy

Thank you for those numbers, very helpful and reassuring :-)

4.1mm works out at ~15.5% of the 6041's inducer area , which is within the normal range in the literature , at 15.5% I'll be needing a slot ~4.5 mm wide , thats good as I think the max would have been ~6 mm if at the top end of the range .

Does the slot have sharp edges or is there a small chamfer , the literature recommends a small chamfer to allow the slot to flow to its full capability.

Does the C30 bleed to atmosphere ??

Cheers
John

[smithy1]

Hi John,
The 4.1mm slot appears to have reasonably "soft edged" slots....as much as a rough casting will allow, the forward and rearward edges don't look to have an intentionally machined chamfer though. Yes, the C30 Anti-surge slot does bleed to atmosphere, via a separate "plenum" on the outside of the compressor impeller shroud. The actual compressor bleed valve is located on the scroll housing just before the air enters the transfer tubes before going to the outer combustion case.

See the "Green section" in the pic below:



Cheers,
Smithy.

[racket]

Hi Smithy

Thanks for that, this are starting to gel :-)

Yep , the C30 looks "just right", I imagine the bleed valve has an opening and closing point in relation to N1 percentages .

Cheers
John

[smithy1]

Certainly does....A lot depends on the T1 temps and N1 speeds but the compressor bleed valve is essentially open until ~90% N1....then it progressively closes until N1 = ~96-97% when it should be fully closed...but this will vary with altitude (P1) and AIT (T1) verses torque load settings etc...On the later engines there's an electronically controlled valve which senses P2, T2 & torque and adjusts the bleed requirements accordingly, methinks this is to "smooth" out the torque delivery at higher power settings, the power delivery was a bit "lumpy" as the bleed valve was between just open and closed ....gone are the days of a simple bleed valve unfortunately...!

Cheers,
Smithy.

[racket]

Hi Smithy

Very interesting :-) ................always nice to have some real numbers rather than the "non dimensional"ones in most technical Papers .

How did the weekend go ??

Cheers
John

[smithy1]

Feb 6, 2017 0:10:16 GMT -5 racket said:

Hi Smithy

How did the weekend go ??

Cheers
John

Sorry guys....Rant mode on/

Weekend was "Interesting" to say the least John!!....Christine and I packed all our gear up and traveled to Mount Panorama, Bathurst on Saturday for the 12hour sports car race, we were in one of the exhibition areas at the auto museum down near the corner leading onto the pit straight ...lots of rare exotics there to be seen, Audi R8 V10's, Aston Martins, Ferraris & Porches of various forms, McClarens etc...  even a couple of Bentley's, they sound fantastic too with their high revving 4.0L twin turbo V8's. The V8 Supercar people were running the event, I did an event for them at the last round of the V8's in Homebush in early December so they knew what I had and had invited me to bring my toys for exhibition at this event.

We arrived at the track ~7am and started setting up all our gear. John, you know the drill and have seen it all before...It was already getting hot ~32C..and continued to slowly increase in temp during the morning.....I also needed to take the temp & ~650m altitude at Bathurst into account, I suspected I'd loose ~8-10% and struggle to produce the normal P2's at the normal rpms etc..so no surprises there.

Obviously I needed to point the tailpipe of the Go-Kart away from all the ridiculously expensive show cars, I ended up setting up on a nice piece of tarmac and pointing it towards the escape road at the end of conrod straight..! Anywho...Whilst I was faffing about I fueled up and gave the little dragster a quick test run to make sure all was good...just a minute or so with a couple of A/B hits etc... I then did the same with the Go-Kart, just a quick run to make sure it would at least start and run with the temp & altitude etc.....She started fine and with a few fire throws and A/B hits, she ran ok albeit with reduced P2's as expected...after ~10 sec of idling, I shut down, cool I said to myself....!!

30 seconds later we had half the "flouro Vest wearing" V8 Supercar security morons and a few of the emergency fire people converging on us...."Oi...You can't do that, you're throwing fire everywhere, it's dangerous"...so I says..."Dangerous to whom..?? And there's no grass or people around for 20 meters in any direction.. You're the ones who invited me here knowing full well what was involved...plus all the race cars throw fire from the exhaust on the overrun and set the grass on the side of the race track alight..!!...are you going to shut them down too??"...to which he said..."Oh no, they're allowed to do that..! But you can't do what you're doing..!" Ppppfffttt..! A couple of quick phone calls to the event organizers and they tell us we can't do any more jet runs....What a load of bollocks...Morons.

Needless to say Christine and I weren't amused,...neither was the car show promoter, (he is employed by the V8 Supercars corp), a ~three hour drive each way for nothing... they had paid for our accommodation for the weekend and for us to be there, including fuel etc.....so 10 mins later we promptly started to pack all our gear up and left for home...and all this before midday on Saturday, waste of time and effort for everyone involved.

I had another car show scheduled for Sunday down at Berkeley but was asked to do the 2 day Bathurst thing instead...So...On Sunday morning we decided to do the Berkeley show instead of the Bathurst thing....We did several engine runs of the dragster and Go-Kart during the day.....not a complaint to be heard or seen and was asked to do two other car shows later in the month...one is an ongoing thing on the second Saturday of each month..! Bonus.

Rant mode off/

Cheers,
Smithy.

[racket]

Hi Smithy

LOL...............you'd think there'd be some consistency , guess they won't have your presence next year on The Mountain.

Sound like you found some clearer thinking officials on the Sunday :-)

Cheers
John

[stoffe64]

Cheer up mate,there are morons everywhere....bound to meet Them now and then!
Cheers /stephan

[smithy1]

Feb 6, 2017 18:20:46 GMT -5 racket said:

Hi Smithy

LOL...............you'd think there'd be some consistency , guess they won't have your presence next year on The Mountain.

Sound like you found some clearer thinking officials on the Sunday :-)

Cheers
John

You'd think so mate...they obviously don't talk to each other, they, (the V8 Supercar people), have become so big now that one hand doesn't know what the other is doing, too many public liability issues and worries instead of doing everything safely in the first place....plus there seems to be too many chiefs and not enough indians. I think we spoke to three different flouro vest wearing "managers" who all thought they were in charge of the same thing and were arguing for 20 minutes among themselves about it all....and at the same time, nothing was getting done...they appeared to be having a committee meeting to discus their next committee meeting ....idiots.!!

The Berkeley event was as good as it gets...plenty of fuel burnt and plenty of engine runs in front of the local punters/spectators with an appreciation of cars...and strange machines like ours..!

Cheers,
Smithy.

[smithy1]

Feb 6, 2017 18:27:46 GMT -5 stoffe64 said:

Cheer up mate,there are morons everywhere....bound to meet Them now and then!
Cheers /stephan

True Stephan......but I seem to attract them more often for some reason....most of the time it's at fairly big or major events where there are more than the normal amount of self appointed experts, most of them are morons.!! Every now and then we come across people who are smart enough to know that a turbine with one moving part is reasonably safe compared to a high revving piston engine...

When I come across a "turbine ignorant" moron at a car show....I just ask them how long their $50k piston engine will run at 100%....given enough fuel, my $5k engine will run all day @ 100%...what about yours..?? 

Cheers,
Smithy.

[pitciblackscotland]

Hi Brett,
I was thinking VIC was the gayhead nanny state Just forget about it mate and move on you will have more shows to do and entertain people As i work in the public sector you have to deal with all the BS and OHS, infection control procedures, guidelines, department policy, ect, ect, ect LOL i think i am working in a sheltered workshop. Mmmm i wonder how i will go when i do a display run with the jet mower

Cheers,
Mark.

[smithy1]

Cheers Mark,

I think the "nanny state" is the whole of Aus these days...Your mower will have their eyes open that's for sure....and because it's "different" you'll have all sorts of issues just getting someone to let you run it at any public event.

I have to produce my public liability insurance certificate at most places now and need to have an "exclusion zone" so people walking past won't get killed...if they can't see or hear a screaming turbine just meters away and realize they shouldn't walk behind it....what chance have we got??...Long gone are the days of "run what ya brung" at any event.

Cheers,
Smithy.