Відео

Oh also the issues you have with priming the test systems could be made less so by using a t fitting inline and 3d printing a simple needle / gate / ball style (albeit cylinder shaped) valve to stop flow with a fill port added either to the print or before the t fitting for filling the source tank. If 3d printing is a problem I've seen people use tyre tubes as temporary pipe plug seals with a bike pump.

Laminar flow is probably desirable, but hard to maintain through any length of pipe, even relatively straight. A straw stack would need to be at the intake so that it could be kept clean, as would definitely clog over time even with a coander filter or similar. One of the advantages of this kind of turbine over a pressure type like a Pelton is it's way more forgiving of particulates, not having a jet nozzle to clog. Not sure what you're meaning in the second comment, is about priming the siphon?

@@OpenSourceLowTech yeah, the benifits of the syphon based system is drawing from a depth so you already avoid a lot of potential blockages from surface debris. For a laminar flow stack I was thinking more of incorporating it into the turbine assembly as part of the bushing before the turbine itself but I guess it can defeat the purpose of making this as low cost and access-able as possible when adding additional complexities. If it's found to have considerable efficiency gains then it could be relatively easy to design the turbine and laminar flow stack as one insert so it's easily removed for maintenance and cleaning. The priming comment was about filling via the system itself so it's primed at the same time during filling but is only really considerable for a test rig not in production and might have issues with pump sizes. Probably more trouble than it's worth 😅. I would be really interested to see what the limits are with stacking the turbine heads within your current design (two or more fans stacked together). Kinda see if you're able to extract more energy from the water by increasing the surface area of the turbine. Times like this I wish I could do the math to figure out what the maximum possible energy for syphon given the pipe size and drop etc.

> avoid a lot of potential blockages from surface debris. Ideally, but unless it's a pretty deep pool / dam things just tend to get mixed and sucked on to your screen in fairly annoying quantities. Still need to properly test coander filters, but they'll need to be fairly large to handle the volume throughput. > can defeat the purpose of making this as low cost and access-able as possible I'm happy for there to be optional add on efficiency boosters for those with the resources, long as the baseline configuration is as universally accessible as possible. Hence the PC fan runner, tho to be fair that does turn out to do a pretty decent job.. > one insert so it's easily removed for maintenance and cleaning. Maybe, if it's a lot of extra oomph. Bit of a bugger of a process tho, and probably fairly often. > primed at the same time during filling This is more or less what I had going in Berlin, but that required a gate valve on the outlet so the water didn't just drain out. Is an option, if you can find a funnel / cone of exactly the right size to fit the gasket, as I was lucky enough to do. > interested to see what the limits are with stacking the turbine heads Yeah same. Will do some further testing on that front when I'm able. > maximum possible energy for syphon given the pipe size and drop etc. The basic equation for max system power is just flow times drop times gravity. But that gets a lot more complicated when considering pipe friction, turbulence, topology, load management, etc etc etc. I wouldn't even necessarily trust a full CFD sim, pretty much just have to build it well as you can and see what the outcomes are.

@@OpenSourceLowTech Thanks for the replies! I fortunately have all the parts in my garage to build one, joys of being a hoarder. Will definitely be playing with this concept. It's a fairly large rig to lug around for field testing so although it will add some internal turbulence I think I'll try corrugated pipe (collapsible) as for the non critical parts vs PVC lengths. Might be lucky enough to minimise the footprint to the dwc junction and 40-60cm of collapsed corrugated pipe.

Car alts have a couple strengths; mainly high max output power and amperage, availability, and often having charge control built in. But the main drawbacks are they're pretty low on volts per rpm (so you have to spin them fast), not usually self energising, and low efficiency over all.

Kind of. It's not antimicrobial in the sense that it kills stuff, but it will pull bacteria and to a limited extent viruses out of the water. But if you don't then keep it clean via backwashing or other sterilisation then it can become a bit of a breeding ground..

Yes, but they're a bit of work..

I've done a bit of work in various refugee camps, mainly in Greece and Uganda, but don't really have the resources to be particularly useful in more active disaster or conflict zones, unfortunately

(BTW, neat video/fun stuff)

The first output testing in Berlin 2020 was essentially exactly that; hoverboard wheel alternator, liquid rheostat variable load. Worked fine and gave full system power numbers. In Nepal tho the main issue was that I just couldn't find a viable option for the alternator. I had intended to use a motorbike alt, but they didn't turn out to be as accessible an option as I'd hoped. Also I kind of just wanted the mechanical output for sake of one less aspect / efficiency gate to potentially complicate the direct comparison of the various runner types. And had used a Prony with the wind turbine testing in Edinburgh (tho with a load cell and ESP32 logger board), so was comfortable enough lashing together a sort of equivalent just using weight scales. Would still love to solve the problem of best alternator options for low resource environments tho..

Screw turbines are a good option in terms of efficiency, but can be a bit of a hassle to fabricate and integrate into the site. Also very low rpm, so usually need a lot of gearing up to get useful voltage. What are some other displacement type turbines?

Thanks and welcome

Cheers!

Potentially, tho the masses involved with the plastic runners are super small, and it is in normal use flywheeled by the alternator. Could have unbalanced torque effects tho if one side of the runner is a slightly better profile than the other..

Thanks!

This is I think essentially the case, yes. The idea was to double up a flow guide bend with a stator action, but previously when I tried just a bit of carved polystyrene to elbow the flow it didn't really seem to make any difference, so I think maybe the water just doesn't mind taking a corner on its own, but really hates wall friction.. I'll next try a kind of internal vector spinner type thing which may or may not help but should be easier to dial in specific angles, and just a more standard stator stack as you described.

Tutorial linked in the description

Presumably for the standard turbine types (Kaplan, Francis, crossflow, etc), but this use case is a bit niche, and fluid dynamics is voodoo.. Will have more of a look tho now that I know the basic efficiencies of each, great if there is.

The euler turbine and pump equation(s) is a useful tool, but it doesn't give detailed blade shapes beyond incoming and outgoing pitch/angles.

Always easiest if someone's already done it, but low head medium power low cost hydro is unfortunately not currently a well catered to niche..

The “Michelin” wheel company R&D expenses are 756 million € per year.

Cheers

Oh yeah, forgot to include the .STL Is now in the description, but also: drive.google.com/file/d/1LKLKvMf1uGRJezQpzQJxcq62L2xLxtP-/view?usp=sharing Let me know how you get on, and any questions etc.

The which?

@@OpenSourceLowTech If you look it up, its the egyptian unusually shaped disk that was made out of shist. Theres a video of a guy using it on ytube in a large paddling pool, with very little input work he could lift the heavy disk and weight on top of it. Theres other videos on redit that show it being used with a drill in a glass of water. It's almost the opposite of an impeller so I think in a tube where the water is coming in from its sides only instead of filling the whole tube it could work better. In order to keep the water flowing to the sides you would obviously need some kind of plug with maybe 3 or 6 fins locked to the edges of the inner tube.

@@OpenSourceLowTech Oh, its the sabu disk, sorry, that was a typo.

It's likely something like that, yes. I'm finding that good propellers don't necessarily make good impellers.

​@@OpenSourceLowTech Yep. This is also true of airplane propellers. Some of them perform better when they have a shield around them to direct the air and some don't seem to have much of an impact. I think the term for them is "ducted propellers'. In a boat setting, the idea is to grab as much of the surrounding water as possible and throw it backward, OR to move a smaller amount of water very fast. Both of these impart Newton's third law (mass, momentum etc). In a tube like you've got, all the water is inherently 'ducted'. So running the horizonal water grabbing ones in reverse ends up performing poorly.

I think the Lily Impeller might work when constrained given it has more room for the water to be expelled. But ultimately having real world tests like you doing is ideal. These things are so hard to think about and often unintuitive.

Thanks!

With the screw runner the flow guide managed to drop both the rpms and torque. May be just increased friction above vector gains. Going to have to try some other options to get a better idea of what's going on.

> I thought that you've given up filming Took about a year, but they finally fixed the channel in 2022. Since then I've just been lazy / distracted. > more than one turbine along the length of the pipe Short answer not really. They'll all steal momentum and power from each other, so you'll multiple your costs but not your output. > making the screw longer Quite possibly. There'll be a sweet spot somewhere for all the various settings, could potentially CFD it, but probably best just print and test a bunch of variations. >the siphon turbine version , or pressure powered Turgo Turgos and Peltons are a lot more efficient, but need at least 20m head to function well. So if you have that much drop, use them. Less; mine should do better.

Doable, but the use case with these tends to be that you always want as much power as you can possibly get out the thing.

@@OpenSourceLowTech True, it's always a fighting balance between adequate head pressure and vectoring the flow at the most efficient angle of attack. I believe your solution lies in in solving that metering and head flow angle though, but that's my opinion. Love your content.

Thanks!