dieselguy86
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Post by dieselguy86 on Mar 8, 2022 22:32:02 GMT -5
Not related to this build, but I just got in kts wheel #6004, a 122mm x 151mm beast of a compressor, couldn't help but to slip it onto the mixed flow gtb62 turbine. Cast compressor is 75mm borg warner wheel, the other billet wheel is a 94mm off a gtx5533r.
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dieselguy86
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Post by dieselguy86 on Mar 6, 2022 22:39:19 GMT -5
Hey all, Like usual plans changed, instead of a micro turbine build into a custom bike frame, I pivoted and am building a turbo based gas producer and its going into an offroad kart frame. I chose offroad because I have lots of country around me and I feel it'll get used more/ more fun not being limited to only smooth pavement. Turbo will be a journal bearing gt4294 running the same 70mm compressor I was already planning on using. Combustor will be reverse flow,case will be 7" fire extinguisher, flametube is 5" outer liner, 3" inner liner, 6" in length. Spent the day modeling an intake manifold to try and get a compact way to get the most smooth and efficient flow over the liner as possible. It will be investment cast out of either stainless or regular steel.
Power turbine is the same modified hp841 freepower unit that will be coupled to the karts cvt fwd/reverse transmission.
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dieselguy86
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Post by dieselguy86 on Dec 23, 2021 18:39:47 GMT -5
John,
At the end of the article, it says they had to open up both nozzles 3% to improve the surge margin with a stalled pt. Does 10.92inĀ² work any better?
-Joe
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dieselguy86
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Post by dieselguy86 on Dec 22, 2021 20:37:34 GMT -5
Hi Chris,
Doing the turbine temp and pressure drop calcs it's really easy to see the extra work required. So it's safe to assume then the corrected raised shaft speed goes along with the additional t and p drops? I didn't know that before, that definitely changes things now when looking at compressor maps.
So would that be the reason for the low trim compressor wheel on the second stage? To keep the pr's up while keeping shaft speed "normal"?
Thanks again- Joe
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dieselguy86
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Post by dieselguy86 on Dec 11, 2021 8:19:31 GMT -5
Hi all,
In my Hugh MacInnes turbo book, he talks about turbocharging at altitude(pg 105). He corrects the absolute temp at 16,000' to show how the denser air slows down the shaft speed.
In my mind the turbo doesn't "see" hot or cold air, rather if the air is thin or thick. If I run his same correction for a high pressure stage in a compound turbo system, it says the shaft speed goes up, due to the heat, despite the inlet air being at a 2.25dr.
Instead of sq/rt the temp ratio, could I sq/rt the density ratio to correct shaft speed?
The caterpillar hp turbo uses a 43 trim compressor, I'm wondering if the large exducer was too keep peripheral speed high with a slower shaft speed.
-Joe
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dieselguy86
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Post by dieselguy86 on Dec 11, 2021 8:00:32 GMT -5
Monty,
Hope all is well there, not sure where your located but hopefully no where close to that monster last night.
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dieselguy86
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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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dieselguy86
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Post by dieselguy86 on Nov 21, 2021 18:04:54 GMT -5
Hi John,
Yea I think going to a 140mm/5.5" case makes sense, not like I don't have the space for it.
I've been thinking on injector placement. I would like to have it spray radially outward just behind the front wall, this will give me the longest combustor.
Other thought was spraying them axially, and making up some "reverse" bell mouth inserts to weld into the front wall to try and "diffuse" and slow the spray down and get it mixed in good. I'm using aeromist nozzles with .012" holes, so should be atomized really good.
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dieselguy86
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Post by dieselguy86 on Nov 21, 2021 13:18:24 GMT -5
Hi all, Printed my diffuser as it is to date, holding it in my hands gives me a better feel for how it really looks vs on a computer screen. Trying to stuff it into a 5" fire extinguisher case, I tried to roughly scale up Gerald Ruttens designs size-wise. His combustor is only ~2.5x's inducer area. I will be right around that, but I think in order to fit all my injectors I'm probably going to have to go up to a 5.5" case.
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dieselguy86
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Post by dieselguy86 on Nov 16, 2021 17:22:42 GMT -5
I love the sound of that start up. Sounds just like the commercial ones.
Is it me or does that p2 seem pretty bouncy at idle? Or is that normal?
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dieselguy86
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Post by dieselguy86 on Nov 1, 2021 13:41:56 GMT -5
Thanks Andy, I used your shaft program (once I converted it to English) and found I need a 20mm shaft. Was hoping to use 61900 bearings (10x22x6).
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dieselguy86
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Post by dieselguy86 on Nov 1, 2021 8:24:38 GMT -5
Hi Andy,
What size shaft and bearings did you end up using?
-Joe
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dieselguy86
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Post by dieselguy86 on Oct 18, 2021 18:24:57 GMT -5
doctorklein, Here's a cut away of the diffuser I'm working on, you can see how the flow path continually grows bigger. -Joe
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dieselguy86
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Post by dieselguy86 on Oct 18, 2021 5:36:48 GMT -5
Pump will be running constant. I'm basically using the same as you, just electronically adjustable.
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dieselguy86
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Post by dieselguy86 on Oct 16, 2021 19:33:58 GMT -5
Hi gents, Micro valve driver is now in. It is small and very cool, capable of 2 inputs/ outputs, either together, seperate, or a mix of either. You input a 0-5v signal and it converts it to a pwm signal. Pwm frequency range from 30hz to 500hz (the direct acting pressure relieving valve I ordered has an optimal pwm of 200hz) Next it has a min setting, this will be my start/ idle setting. Because I'm using direct injection with no preheat, I need the fuel to immediately come in at a certain psi. Obviously if there's a min setting, there's also a max setting, aka 100% rpm. The part I like the most is it has a programmable ramp time, this is how fast it reacts to throttle changes. So I can move the throttle as fast as I want without worrying about causing a flameout. Programming is done via jumpers and pot in the back of it, there is a gate module that connects to it and uses a wifi signal to allow remote programming via there software. I didn't buy it as it was an extra $200, but I'll probably get it as it's going to be a pain having to move jumpers and guess where to move the pot when adjusting things like pwm min/ max and ramp time. Red: +vdc Black: -vdc Orange: +5vdc reference to throttle potentiometer Blue: output of pot into the #1 input Yellow: pwm output to the pressure relief valve Doesn't get much simpler than that, now I hope it works good. I hate temperamental electronics that don't have repeatable accuracy.
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