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Post by 90GTVert on Jun 30, 2020 18:09:25 GMT -5
I was screwing around with the pump more. Wanted to retry 9000RPM tests and I was trying to get shots of the clear hose on the pump outlet to show air bubbles that appear at high revs and see if it changed much with the outlet submerged.
9k tests were the same result. 48L/min. Wound it up about as fast as I can go to 10k and that was exactly the same at 48L/min.
I was messing with the speed control and I can go back and forth from 10k-ish to a bit lower and watch the outlet saturate with bubbles and go back to steady and saturate and back to steady as RPM rises and falls. That's even with the outlet submerged. I wonder how much a pressurized cooling system would change that, if at all?
Had to empty the 5gal bucket somehow, so I cranked the pump up to 8000RPM and emptied it in the driveway to see what 68L/min looks like. It's basically a garden hose.
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Post by 90GTVert on Jun 30, 2020 23:01:24 GMT -5
Prob the best news of my day is that I found a clip of a kart axle spinning the pump. It's on a YouTube channel from Australia named Power Republic. I got in touch and he said I could use a clip. It's surprisingly difficult to find pics or clips close enough to see, but far enough to actually tell it's the axle. Quite happy to be able to put a quick clip in the vid so we can all see it in it's intended home.
I know. I'm a dork. lol
Anyway, Derek seemed glad to help and his vids are good quality so check out Power Republic on YouTube if you wanna see some kart stuff.
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Post by oldgeek on Jun 30, 2020 23:22:36 GMT -5
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Post by 90GTVert on Jul 1, 2020 7:15:38 GMT -5
The main question that I'm left with is whether I'm seeing cavitation or aeration bubbles in the pump outlet. Unfortunately, I only had enough clear hose to do the outlet. If it's cavitation, I should see a clean supply with an outlet full of bubbles. If it's aeration, I should see the air bubbles passing through the whole system.
The pickup is near the bottom of a bucket, but the bucket is turbulent when the outlet is also in it so I can mess with the pump for more than 10-15 seconds at a time at high pump speeds. That's the only way that I would think it could be aerated. Doubtful that there's a leak between one end of the hose to the pump, with a clamp snug on the pump.
I could go buy clear hose for the inlet and more food coloring, but I don't think I'm going to. This seems to primarily be an issue at speeds higher than I plan to drive the pump. Even if it is cavitation, I don't know that it proves anything to see it in this system vs a sealed cooling system under pressure.
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Post by 90GTVert on Jul 1, 2020 13:29:18 GMT -5
There's really no reason that I need to know this, because I'm not gonna spin the pump that fast... but you know I just couldn't leave it alone. I chopped up my hoses and used steel tubing as couplers so I could have clear on the inlet and outlet of the pump. Only had a few drops of food coloring to change the water the palest shade of pink, but luckily it wasn't really needed. Most of you won't need this, but inlet in the foreground, outlet hose in the back of the pics. Lower RPM Very High RPM There is some aeration, because I'm moving a lot of water and the inlet and outlets share a 5 gallon bucket. It's enough at high revs that it's swirling and splashing water out. Still, if you look at those pics you can see there's a clear (or actually not clear) difference in the outlet hose at high revs and not much difference in the inlet in either pic, so I'd have to guess that's cavitation. It's more obvious when you can watch it moving, but that'll have to wait for whenever I get a vid of all of this together. EDIT : Oh, and I stuck my hand in the water to check hose positions while the pump was going and damn that thing has some outlet pressure and inlet suction. It's kind of impressive what such small pumps can do. I need a diesel powered test rig to play with.
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Post by repherence2 on Jul 2, 2020 20:49:12 GMT -5
What about using a long clear hose to loop the discharge back to the suction and running it at high speed for a little while?
Cavitation bubbles end up collapsing and disappearing after a while. By running it in a closed loop, you can figure out if it is cavitation versus aeration. If it is aeration, you will be left with a bubble in the closed loop after the high speed run. If it is cavitation from the pressure differential at the tips of the pump impeller, all the bubbles should collapse and disappear from the fluid after the high speed run is secured.
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Post by 90GTVert on Jul 3, 2020 8:06:58 GMT -5
What about using a long clear hose to loop the discharge back to the suction and running it at high speed for a little while? Cavitation bubbles end up collapsing and disappearing after a while. By running it in a closed loop, you can figure out if it is cavitation versus aeration. If it is aeration, you will be left with a bubble in the closed loop after the high speed run. If it is cavitation from the pressure differential at the tips of the pump impeller, all the bubbles should collapse and disappear from the fluid after the high speed run is secured. I think the clear hose that I have already shows that there's way more air coming out at speed than going in. Maybe I'm wrong. My concern with closed loop is that I may never get the air out in the first place. I'd figure a fitting would be needed somewhere inline to try to bleed it off. I guess that could be put down low once bled so air really shouldn't hide there. I had basically decided that I wasn't putting anymore into this. If more people feel that the amount of air exiting vs entering in my short clear sections is not proof of cavitation, then I may put more into it to buy more hose and some sort of inline fitting. There will be more delay too because I ain't going into Lowes (still haven't been in a business since March and not starting now for this) so amazon says Thur for clear hose if ordered now. Gimme a few and I'll see if I can put a quick clip up so you guys can see some vid for yourself and tell me if it's uncertain.
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Post by 90GTVert on Jul 3, 2020 8:26:10 GMT -5
It may take a minute before it's processed in 4K, but it's up. You can see the inlet changing too, but not like the outlet. Then again, I guess that could be just the post pump effect on air in the system. Now I'm not as sure either, but damn I hate to be in August before I'm even getting the pump on the scoot. lol
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Post by aeroxbud on Jul 3, 2020 8:34:48 GMT -5
That is quite interesting. Cool to watch. It does look like it's just the force of the impeller causing it.
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Post by 90GTVert on Jul 3, 2020 11:43:16 GMT -5
I'm probably going to try it. Dammit. lol I want so badly to say who cares and walk away since it literally has no affect on what I'll be doing to the scoot... but I can't just turn it off.
I wonder if I can get away with the cheap non-reinforced clear tubing or if I have to have reinforced. Less money but also very clear. There is a lot of suction so I don't know if the pressure with equalize well enough being a loop that it's fine or if the hose is going to collapse on the inlet side of the pump.
I'm thinking I can spend less if I just use the steel tube that I have been using as a coupler to make a tee. Maybe I could get away with 1/4" fuel hose to connect the tee to a fuel shutoff and give me a way to get rid of air if that is the high point and to add fluid (slowly). I don't want to be so cheap that it doesn't work though. Thoughts welcomed.
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Post by oldgeek on Jul 3, 2020 14:57:36 GMT -5
Short opinion. Get whatever you are going to do done and send it, riding time is a terrible thing to waste!
Longer opinion. In the event I am totally missing what you are accomplishing,just ignore the following words. You probably already understand what I am trying to say better than I do.
You have nice data to look at so far, but it becomes irrelevant when you hook it up to your actual cooling system. I suspect supply to the pump will be limited by throughput of all other components of the cooling system. The low pressure seen at the pump intake will cause cavitation at the low pressure area. The low pressure in relation to overall system pressure turns some of the water to vapor, it boils (cavitation) I suspect the "bubbles" eventually disappear down the line as they encounter higher pressure and collapse giving their heat back up. Any bubbles at all severely lower water throughput through your cooling system.
I still believe there is a point that the pump is overdrive and that point is going to be a lower RPM that we expect. I understand you need to find a balance between WOT and idle. What that point is I have no idea.
I may be totally wrong about all of this and if I am you will surely prove me wrong. Sorry if I am sounding like an A**.
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Post by 190mech on Jul 3, 2020 17:08:26 GMT -5
Like my NASA engineer buddy says;"It's time to shoot the engineers and get on with this project!"
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Post by aeroxbud on Jul 3, 2020 17:49:18 GMT -5
Like my NASA engineer buddy says;"It's time to shoot the engineers and get on with this project!" Is that about the time they ask for volunteers? 😁
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Post by 90GTVert on Jul 3, 2020 18:18:30 GMT -5
Great. I didn't really wanna go any farther and called it done for whatever it is on video right after the last test, but then if you put ideas in my head they rattle around and sometimes I can't shake them or feel like I should do it for the sake of video and those watching the project in general. Considering there will be weeks and already at least $100 of stuff not for the actual scoot involved in a video to gross $4-5, I can walk away here and call it good enough without feeling too bad about it.
Again, for my own personal scoot issues, all I needed to know was roughly how much it flows. I don't care what it does beyond 6000RPM because I'll never have something that revs high enough to spin the pump that fast with the pulleys that I chose (40%).
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Post by 90GTVert on Jul 7, 2020 21:23:16 GMT -5
Don't worry; the reason that you haven't seen updates isn't that I've been doing more tests. I've been spending all of my time editing. So, here's the video all about the kart pump testing and some background, plus even a quick bit about the Yamasaki : youtu.be/rqXBed2o8-M
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