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Post by smithy1 on Mar 15, 2016 19:01:30 GMT -5
Hi John, Managed to fit the "new" C20B fuel pump/drive motor setup to the beast yesterday, should have it all wired in and plumbed up this afternoon, I'll take a couple of photos for you to peruse. I've had to fit the pump and electric motor up front where the original battery used to live, no room anywhere else for it I'm afraid. I found I can run the system on 4 cell Li-Po batteries which run to 16.8v fresh off the charger. In theory I should be able to achieve ~350-400psi without too much drama, I suspect the fuel nozzle will need about @~125-130psi fuel pressure to achieve a reasonable idle, so hopefully the fuel atomization will be better with the higher pressures. I did a quick pump run "in isolation" yesterday to see what sort of current I'll be pulling, at 350 psi the electric motor was pulling ~18.5amps....which is a bit less than I had imagined....so all good. I'll obviously need to do a couple of engine test runs to get a good handle on what the engine needs though since our pressure ratio across the flame tube just isn't there, to compare it to the C20 may be a bit off as far as fuel requirements go, we'll have to wait and see I guess. Andrew mentioned to me that I may now have more "real" turbine engine parts than would be considered a DIY project..! He may well be right..  Cheers, Smithy. |
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Post by smithy1 on Mar 16, 2016 13:58:57 GMT -5
Managed to get everything plumbed in and wired up yesterday, a few pics for you: 36v 800watt motor driving a C20B fuel pump:  Twin 10,000mah 4cell Li-Po batteries to power the whole show, soon to be upgraded to twin 16,000mah, should be good for at least ~3/4 hour of continuous running:  Cheap 500psi gauge to accommodate the extra pressure:  John, I did use the pump "by-pass" port in the end, I found the amount of fuel being by-passed back to tank was causing a significant amount of "fuel frothing"....which in turn caused some cavitation of the pump and erratic flows and pressures....was much better using the pump's own by-pass fitting. I ran the fuel and oil pumps at the same time and she's pulling ~23amps when there's 70psi oil pressure and ~50psi fuel pressure load. Cheers, Smithy. |
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Post by racket on Mar 16, 2016 18:10:48 GMT -5
Hi Smithy
All looking good there :-)
Like the coupling between motor and pump .
LOL, yep , the DIY aspect is slowly becoming more professional .
It'll be interesting to see how the changes affect the engine's combustion .
Cheers
John
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Post by smithy1 on Mar 16, 2016 21:38:02 GMT -5
Hi Smithy All looking good there :-) Like the coupling between motor and pump . LOL, yep , the DIY aspect is slowly becoming more professional . It'll be interesting to see how the changes affect the engine's combustion . Cheers John Yeah...hopefully it'll run ok...was running "reasonably" well before, albeit with a few "flutters" etc...I suspect the atomization still wasn't the best with the lower pressures I was using. As you're well aware, the C20B fuel nozzle is designed to work at much higher pressures than we would normally see for us DIYers...I thought I might have been able to get away with the lower ~100-125psi at full noise of the 044 pumps but it appears not.  At idle the fuel pressure was only ~35psi...so methinks the fuel droplets were just too large. Coupling is just a simple piece of 20mm ally rod, 12mm hole through the middle, grub screw to secure to motor shaft "flats".... I then just bored a recess large enough to take the end of a 15mm 12 point socket, cut & turned to size, pressed and bonded it in with loctite and it just works..! Took ~1-1/2 hours to make.... Simple is a good thing...  Cheers, Smithy. |
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Post by racket on Mar 17, 2016 3:39:36 GMT -5
Hi Smithy
Yep, we probably need >50psi for a reasonable atomisation and was the reason why I needed to run 750 psi at full power on the TV84 engine with only the "simplex" nozzle , ...........the atomisation was pretty good when testing into a large pickled onion bottle using >1,300 psi :-)
Cheers
John
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Post by smithy1 on Mar 17, 2016 14:01:15 GMT -5
LOL...I hope you had already consumed the pickled unions..!
1300psi is getting up there mate, the pump I have can do that, but I don't need anything like that sort of pressure for the duplex C20B nozzle...~450psi max will suffice. The C20B engine runs 280lb-hr @540psi when on it's max flow stop. The 6041 won't need anywhere near that much fuel and I'm thinking ~200-220lb-hr ish will be plenty, at those sort of flows the nozzle normally sees ~250-300psi from the FCU/pump.
Weather permitting I hope to run the 6041 this coming weekend.
Cheers,
Smithy.
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Post by racket on Mar 17, 2016 18:04:22 GMT -5
Hi Smithy
LOL , nah , I got the bottle from Vinnies , it was one of those big 5 litre ones with a screw cap that I was able to mount the fuel nozzle into and view the spray through the glass wall .
It surprised me how much energy was in the spray, it really churned up the fuel sitting in the bottom of the jar even after hitting the wall and sliding down it .
Weather should be perfect this weekend :-)
Cheers
John
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Post by smithy1 on Mar 20, 2016 15:58:11 GMT -5
Hi All, John, I did a car show at Penrith yesterday and the C20B fuel pump and fuel nozzle appears to work fine , combustion is much better with no fluttering and is "much" smoother than with the 044 pumps, I suspect due to better atomization with the higher fuel pressures. Idle fuel pressure is ~80-85 psi and temps are pretty much the same as before, in the high 490C range. Fuel pressures, as expected, rise quickly with throttle increase, at ~70-75% I was seeing a good 275-280psi...so all good in that respect... but I'd prefer something a little higher tbh. I'm using a "stock calibration" C20B fuel nozzle so I may need to "adjust" fuel nozzle flows down a small amount to help raise the pressure slightly due to the lower mass air flow of the 6041 compared to the C20B.... but it's pretty close to the mark as it is. Oil pressures are excellent with ~70psi+ cold and only dropping to just under 60psi when temps rose to ~85-90C....this oil temp was a little higher than I had seen previously but still well within what I'd call an acceptable range, even after 3 runs it never went above 90C. I'm still having an issue with flame-out during deceleration though, not real sure how to rectify it, I have a sizable accumulator in the system but it doesn't appear to help much..?? I actually have video of the first run of the day, will upload this evening, you'll be able to hear the flame-outs and "re-ignition pops" happening, I keep the igniter running all the time just to be safe. During the day I only ran to ~70-75% for fear of "jumping the chocks", but there's still plenty of thrust happening even at these lower rpm runs, you can actually see the chassis flexing at times. Cheers, Smithy. |
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Post by racket on Mar 20, 2016 16:48:45 GMT -5
Hi Smithy
Nice one, 80 psi would be giving good atomisation :-)
The flameout has me a tad baffled as your idle fuel pressure should be high enough to cope, but the actual flow might be a bit "low" due to you running a fairly low idling temp because of the "large" A/B nozzle compared to a normal setup without A/B or having freepower downstream .
The accumulator will be struggling to cope due to the higher fuel pressures , assuming a 100 cc capacity of air without the pump on , with 85 psi the air is going to be compressed to only say 20 cc , at 275 psi its going to be down to 5 cc , so theres only going to be 15 cc of fuel available during the deceleration, thats only about half a second's usage at high powers .
I'm down to the last job on the 12/118 , gotta go buy a couple of metal olives for the 1/2" pressure lube plumbing , pipe is made , just need the olives , but its been bucketing down rain here so might wait a while til it stops
Cheers
John
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Post by smithy1 on Mar 20, 2016 17:48:08 GMT -5
Hi John,
You may well be right regarding the A/B nozzle being a tad large, I might give the pipe the old "Adjustable Tab" treatment to see if it helps, similar to how the old J34 engine pipes were "trimmed" back in the day. I also have a piston type "nitrogen" filled accumulator at my work which I can adjust the pressure to suit, might be worth fiddling with.
I would've assumed that as the pressure in the accumulator decreases with the throttle decrease, the air volume would increase forcing the fuel into the line? The pressures pretty much follow the throttle, which is why I was a bit perplexed at the flame-outs. I do have a check valve in the line but it is downstream of the accumulator...I wonder if it would help if I fitted it upstream..? Your thoughts?
The actual fuel pressures at the fuel nozzle may be a tad less than indicated on the gauge due to losses down the line, but it shouldn't be a dramatic difference, maybe 5psi or so. I'm taking pressures at the fuel control where you had it originally, and there's a good 1.5m of -4 fuel line from there before it hits the fuel nozzle, if necessary I can "T" a pressure pick-up off the fuel nozzle fitting, but essentially the pressure readings are mainly for reference.
Really looking forward to the 12/118's first run. Yeah, has been raining here too but not too heavy.
Cheers,
Smithy.
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Post by racket on Mar 21, 2016 0:22:40 GMT -5
Hi Smithy
The check valve needs to be between pump and accumulator so that as soon as the fuel pressure drops on deceleration the check valve closes and the fuel in the accumulator is forced into the engine by the "previous" high air pressure in the accumulator , until equilibrium is achieved between fuel supply pressure and the air pressure on the other side of the check valve , the check valve lifts and pump fuel flows to the engine .
Cheers
John
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Post by smithy1 on Mar 21, 2016 1:09:00 GMT -5
Hi John, Understood...I'll move the check valve to the other side of the accumulator. Here's a wee video of yesterday's short run, take note of the "flame-outs"... vimeo.com/159749697Cheers, Smithy. |
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Post by stoffe64 on Mar 21, 2016 1:53:25 GMT -5
Interesting thing,thanks for sharing it!
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Post by racket on Mar 21, 2016 2:41:30 GMT -5
Hi Smithy
Yep , classic lack of accumulator fuel reserve .
She's sounding sweet though :-)
Cheers
John
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Post by smithy1 on Mar 21, 2016 3:20:41 GMT -5
Hi Smithy Yep , classic lack of accumulator fuel reserve . She's sounding sweet though :-) Cheers John All good..I'll take your advice and move the accumulator to the correct place, you're probably right, the fuel is more then likely going the other way for a few micro seconds... instead of through the fuel nozzle, check valve upstream should fix that, I'll fit it just upstream of the shut-off tap and we should hopefully have a smile next time..! Yeah, she's actually running pretty well, engine feels strong and smooth, starts well, accelerates nice and hard without surge etc...so we can be happy about that....which means the flame tube and fuel nozzle numbers must be close to the mark...just need to sort the flame-out issue and we'll be good to go. The "Twin 16,000mah" 4 cell lipo batteries in parallel worked well too....did three 5-6min runs and still had a goodly amount of capacity left in them, I charged them this afternoon and they only took ~50% so plenty in reserve ....not surprising really with 32,000mah and 320amps available..! There's always something to keep my little brain cell ticking over and always mods/repairs to do during downtime..! I'm really enjoying working on the kart lately, gives me something to look forward to. Cheers, Smithy. |
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At idle the fuel pressure was only ~35psi...so methinks the fuel droplets were just too large.
