Author Topic: 5kw Poncelet Wheel Project  (Read 149542 times)

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skid

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Re: 5kw Poncelet Wheel Project
« Reply #231 on: November 09, 2017, 01:26:03 AM »
I've been operating for a month or so now and have a few observations. So far we have had a very dry fall and in the last week temperatures have dropped below freezing for a few days which is unusual for this time of year. River flows have continued to drop.

Freezing - The water wheel doesn't like it. After a few days I had a huge buildup of ice on it, enough that it built up in the vee grooves of the water wheel pulley and caused one belt to fall off. The wheel itself got so heavy the hydraulics strained to lift it out of the water. Going forward, if the temp drops below freezing for any length of time I will pull the wheel out of the water.

Efficiency - I can see a few ways in which I can improve the efficiency of the wheel. The first thing I will do is close in the inner diameter of the blades. Water is flowing through the blades and out the middle of the water wheel which is definitely hurting the efficiency. If I close it in with some sheet aluminum I can see efficiency improving. Either that or increase the length of the blades towards the middle and increase the sidewalls. I have a couple other things I can do as well to make more power.

Wheel elevation in the water - I adjusted the ram so I could push the wheel lower into the water. Max power is made with water well up the side of the wheel rim. About 3/4 of the way up seems to be the best.

Power level - Flows should pick up in a few days as heavy rain is being forecasted. So far my max has been 875W according to my inverter, but flows have been really low for this time of the year, now dropping to less than 20CMS (cubic meters per second). Hopefully we'll get sustained flows in the 100-200CMS range which really speeds up the flow.

MattM

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Re: 5kw Poncelet Wheel Project
« Reply #232 on: November 09, 2017, 07:28:05 AM »
So by closing in the spaces you're going for more of an undershot wheel?

Do waterwheels ever use skirts - like a tent over the wheel down to water level - to keep ice from freezing the wheel.  It would seem if the ice was kept out of the wheel, and ice could safely attach around the skirt in a controlled manner, then you could generate during freezing conditions.  I wouldn't want the skirt attached to the wheel itself for obvious reasons.  I was thinking more like a floating dock situation..  By doing this you eliminate the pucker factor when you wake up some morning and realize your weather changed on you.
« Last Edit: November 09, 2017, 07:40:53 AM by MattM »

SparWeb

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Re: 5kw Poncelet Wheel Project
« Reply #233 on: November 09, 2017, 03:29:04 PM »
At first, I was thinking the same thing as Matt.  But then I started wondering about how the ice forms over the water and some problems became apparent.  Ice tends to grow from shore toward the middle, so it will reach out from your bank toward the wheel.  The churning action around the wheel will prevent ice from forming on the water's surface, but it will adhere to the sides and buckets of the waterwheel.  It will grow a rime over all of the surfaces that get splashed, making it heavier.  I don't see weight as a problem on your humungous beam, but the pivot point will be more stressed now.

Putting anything into the water upstream of the wheel, like a dock or a pier, will slow the water down and could also offer another spot for ice to get a purchase and grow on the surface.

Does your river usually freeze over in the winter?
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skid

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Re: 5kw Poncelet Wheel Project
« Reply #234 on: November 10, 2017, 12:21:40 AM »
The river doesn't freeze. The issue was the air was below freezing, and the parts of the wheel that don't contact the water dropped below the freezing point. Any water dripping from the buckets hit the freezing metal and froze to it.

The parts affected were the axle, the struts, the big pulley, and the arms that support the wheel. I had icicles 3 feet long hanging off the arms. The axle had ice 3 inches thick around it. I had to scrape the ice out of the pulley grooves to get the belt back on.

It doesn't normally drop below freezing here for any long lengths of time so I'll just lift it out of the water until warmer weather arrives.

SparWeb

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Re: 5kw Poncelet Wheel Project
« Reply #235 on: November 10, 2017, 01:12:19 AM »
You sure ain't in Alberta, then.
No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it.
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skid

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Re: 5kw Poncelet Wheel Project
« Reply #236 on: November 26, 2017, 06:49:08 PM »
Spar Web,

Nope not Alberta, coastal BC. Still quite warm here today.

Welp, bad news. I've been hearing some funny sounds out of the wheel for the last few weeks. Saw the wheel shuddering a bit, thought belts were slipping so tightened them up along with everything else that had a bolt or nut on it. Sound persisted until a couple days ago when it was really screeching.

Pulled the wheel out of the water and pulled the outboard bearing cap - Full of water. Pulled the inboard cap - Bearing cage hanging out the side and the outer race blue.

I noticed that the wheel wasn't centered on the fork as well. The outboard bearing controls axial thrust. Put a pry bar on the wheel and found I could move the wheel back and forth axially on the bearings.

Since the bearing seals sit on the shaft and rotate against the housings it appears that when the wheel was thrusting back and forth axially the seals were losing contact with the bearing housings, then admitting water.

The Thrust retainer was obviously not tight enough despite me hammering it up with a punch and then locking the retaining nut.

I've ordered new bearings and will make darn sure I get my largest ball peen hammer and hammer the crap out of the thrust retaining nut so it can't move once I replace the bearings.

Right now the river is really flowing and I could make some good kilowatts too. Hopefully this was the cause of the oscillating power levels seen on my inverter.


SparWeb

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Re: 5kw Poncelet Wheel Project
« Reply #237 on: November 26, 2017, 08:19:10 PM »
Aw ain't that just they way it always breaks: when it's really flowing the problems show up.
No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it.
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skid

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Re: 5kw Poncelet Wheel Project
« Reply #238 on: November 30, 2017, 01:17:19 AM »
Took everything apart today. I pulled the wheel off the frame and brought it to my shop for ease of working on it and to keep out of the rain as much as possible. Tractor could just barely lift it.

Had to use a couple of large pullers to get the large pulley and then the bearings off the axle. Everything was on tight!

Looks like water got into the bearings before it even got into the water. It sat for almost two years and judging by the rust marks rusted for almost that long. Now I know why people use wood or UHMW plain bearings as they are immune to water.

I cleaned everything up, scraped off all the rust and used a wire wheel to polish everything. I installed the new bearings being sure to really pack them with grease. Last time I put in the bearing company's recommended amount of grease. Because this is a very low speed application, this time I packed in as much grease as possible. And then hit it some more with the grease gun when it was assembled.

Tomorrow I'll bring the wheel back down to the river and hopefully get it up and running again.

SparWeb

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Re: 5kw Poncelet Wheel Project
« Reply #239 on: November 30, 2017, 02:21:32 PM »
I hope so too
No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it.
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skid

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Re: 5kw Poncelet Wheel Project
« Reply #240 on: December 02, 2017, 12:14:16 AM »
Got the wheel back up running today. Nice and quiet now.

I made sure to grease everything really well and made sure the bearing seals were contacting the housings properly. Hopefully no more water issues. I should plan on splash shields for the bearings, and a small roof for over the generator to try to keep it dry too.

I do notice that the generator output isn't jumping around as much as before. This indicates to me that the bearings were damaged right from the get go before, as output was jumping around greater than 300W at a time when I first put it in the water. Now it's steady within 100W.

River flows are down now again, but when they come up I hope to start generating some KW's. I maxed out at ~1500W before but that was with the wheel shuddering as the bearing was locking up. Crap, at the time I thought the belts were slipping and tightened them up more then which sped up the demise of the bearing...

MattM

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Re: 5kw Poncelet Wheel Project
« Reply #241 on: December 02, 2017, 03:20:39 PM »
Could torque from the waterflow be twisting on the bearing, creating excessive side loads?

SparWeb

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Re: 5kw Poncelet Wheel Project
« Reply #242 on: December 02, 2017, 05:55:03 PM »
Good to hear.
And you've backed off the belt tension, too, I guess?
No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it.
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skid

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Re: 5kw Poncelet Wheel Project
« Reply #243 on: December 02, 2017, 09:46:54 PM »
Could torque from the waterflow be twisting on the bearing, creating excessive side loads?

The bearing loading from the wheel is evenly balanced, plus the bearings are quite large for the application. The axial loading is minimal, while the radial load is low and low speed. The inboard bearing does have a higher load imposed by the belts, but compared to the generator bearing which so far has had no issues, is at least twice the size. The generator bearing is a single deep groove ball bearing while the waterwheel bearing is a double spherical roller bearing. From Wikepedia - Most spherical roller bearings are designed with two rows of rollers, allowing them to take very heavy radial loads and heavy axial loads.

Good to hear.
And you've backed off the belt tension, too, I guess?

Belt tension is what I would consider to be minimal considering the high torque generated by the wheel. I've always had it on the loose side so when the wheel was shuddering I thought it was belt slippage.

Before the wheel was always speeding up and slowing down, now it is running at a steady but noticeably slower rpm. The inverter is now allowing it to load up properly now it appears. I'll keep a close eye on it for now...

hiker

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Re: 5kw Poncelet Wheel Project
« Reply #244 on: December 02, 2017, 10:38:43 PM »
With all that high torque...you could speed things up a bit...?
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skid

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Re: 5kw Poncelet Wheel Project
« Reply #245 on: December 02, 2017, 11:02:09 PM »
With all that high torque...you could speed things up a bit...?

I don't think it would make any difference power-wise. The inverter loads it down to make max generation. To make more power I need to create more blade area. I'm looking into that.

One thing I've noticed is that there is a bit of inefficiency from blade slap from the back of the blades hitting the water. It sounds like a bass drum. I'm looking into extending the blades another 2 feet in diameter, and widening the blades as well. I mentioned to my CAD buddy to see if the blade extensions can be shaped in a V as well to create even more surface area and to reduce blade slap as well.

george65

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Re: 5kw Poncelet Wheel Project
« Reply #246 on: December 03, 2017, 05:02:20 AM »

There is a lot written about belt tension but a mate who worked in industrial power transmission had a rule with it..... Only has to be tight enough not to slip and if it's obviously too tight, you need more belts so you can have them relatively slack.

Always worked for me. I don't like tight belts because of the loads and friction they impose. When pulleys and belts are in good nick and under stressed for the job, you can run them relatively loose and they still transmit the power fine.

MattM

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Re: 5kw Poncelet Wheel Project
« Reply #247 on: December 03, 2017, 07:39:49 PM »
I know this is counter-intuitive, but what if you traded out the rigid buckets for flexible bands?  Kind of a mudflap supported on the sides.  As it strikes into the water it gives, but as it submerges in deeper water shifts pressure to the backside.  It should be much quieter.

george65

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Re: 5kw Poncelet Wheel Project
« Reply #248 on: December 04, 2017, 06:09:38 AM »

No doubt it's been done and there is data somewhere but the above suggestion gives me a thought....

What if the blades were hinged or pivoted?

They would enter the water on the thin edge, push back on stops when the water is driving them  but would probably pivot and pull out the water more cleanly instead of trying to lift it at an angle as they withdraw.  I don't think it would be quieter, probably clank and even squeak a bit  but possibly reduce some of the drag as the blade would I think lift out the water on it's edge rather than having water running off the back as resistance.

Wonder what such a wheel is called and how it is efficiency wise?

Mary B

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Re: 5kw Poncelet Wheel Project
« Reply #249 on: December 04, 2017, 06:11:26 PM »
More moving parts = more points of failure... KISS principle comes to mind...

keithturtle

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Re: 5kw Poncelet Wheel Project
« Reply #250 on: December 05, 2017, 02:55:50 AM »
I thought extending the inner lip of the bucket inward with a curl, more like the Poncelet design, to capture more of the energy.  Once the flow  "hits the wall" the  velocity will play a bigger role

Maybe.

Thanks for sharing the saga

Turtle
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skid

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Re: 5kw Poncelet Wheel Project
« Reply #251 on: December 05, 2017, 04:03:02 PM »
I thought extending the inner lip of the bucket inward with a curl, more like the Poncelet design, to capture more of the energy.  Once the flow  "hits the wall" the  velocity will play a bigger role

Longer blades extending out further will do the same thing I'm hoping. If after adding longer blades and water still pours out the middle of the wheel I will seal the blades off as there is definitely lost energy there.

I was carefully analyzing the wheel's operation yesterday and noticed that the blade slap is actually the water hitting the front of the blade, not the rear. Sounds like the bass drum in a teenagers car stereo. My neighbor says he can hear it when he is near the river.

keithturtle

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Re: 5kw Poncelet Wheel Project
« Reply #252 on: December 05, 2017, 10:10:42 PM »
My neighbor says he can hear it when he is near the river.

That's not a good omen.  Maybe you'll be successful where others have failed in the acoustic dampening arena

https://www.enoisecontrol.com/noise-canceling/

At least it is rythmic, should make it easier

Approach it with earnestness

Turtle
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MattM

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Re: 5kw Poncelet Wheel Project
« Reply #253 on: December 05, 2017, 11:41:33 PM »
You can only grab so much energy.  The issue doesn't sound like how much energy, but rather what happens to the excess energy.  It sounds like you displace so much water it is audibly significant.  No matter how the bucket is shaped the laws of physics prevents any improvements to capturing the energy.  I'm thinking you want a solution that allows that other 33% you cannot capture to quietly continue downstream.  You want the rig to move with the flow displacing a minimal amount of water.  My intuition leans toward allowing 33% of the water to pass through undisturbed.

joestue

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Re: 5kw Poncelet Wheel Project
« Reply #254 on: December 06, 2017, 01:41:00 AM »
can you make the buckets helical?
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MattM

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Re: 5kw Poncelet Wheel Project
« Reply #255 on: December 06, 2017, 06:59:31 AM »
That would be like a massive redesign.  He's put a ton of effort into this thing and it's more or less an exercise in aesthetics.  I was thinking less buckets or sideways, but again a major change.  His new lip might actually bite the water quieter.  How would somebody manufacture a helical prop to fit his rig?
« Last Edit: December 06, 2017, 07:36:18 AM by MattM »

joestue

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Re: 5kw Poncelet Wheel Project
« Reply #256 on: December 06, 2017, 01:17:02 PM »
Doesnt have to be a true helix.
My wife says I'm not just a different colored rubik's cube, i am a rubik's knot in a cage.

Mary B

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Re: 5kw Poncelet Wheel Project
« Reply #257 on: December 06, 2017, 06:52:07 PM »
K.I.S.S. !!!

Minor bucket mods yes, major redesign? That could take a year or more.

SparWeb

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Re: 5kw Poncelet Wheel Project
« Reply #258 on: December 06, 2017, 08:50:02 PM »
Gotta take Mary's side here.  Skid is already doing well already.  No sense being greedy.
A functional energy-producing system is more important than tweaks that might (or might not!) improve its performance.

Skid, if you want to chase the noise and splashing problem any more, might I suggest something like a go-pro camera attached to a spoke pointed at the paddles.  Then you would see the whole water immersion process from the paddle's perspective and know for sure what's causing the slap, and if you should do anything about it.
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MattM

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Re: 5kw Poncelet Wheel Project
« Reply #259 on: December 06, 2017, 08:56:48 PM »
Parachutes with a hole in the apex are more stable than fully enclosed parasols.  They form a targeted amount of drag rather than attempting a full stop of the air.  I wonder if the solution is allowing water to pass through easier as the paddle strikes the top edge of the water.

Frank S

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Re: 5kw Poncelet Wheel Project
« Reply #260 on: December 08, 2017, 10:09:10 PM »
Almost sounds like a cavitation splash
https://www.youtube.com/watch?v=OPfjoAQxvcQ
 just adding an inner shield may do some to quieten the blades at the same time improve output
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clockmanFRA

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Re: 5kw Poncelet Wheel Project
« Reply #261 on: December 09, 2017, 11:25:20 AM »
I thought this might help.

Pics of a local undershot wheel, this stopped working in 1960. But being in France nothing gets moved about much.

Everything is possible, just give me time.

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skid

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Re: 5kw Poncelet Wheel Project
« Reply #262 on: December 11, 2017, 10:25:11 PM »
Very interesting and useful Clockman! I was just going through a blade profile analysis with my CAD buddy based on several different immersion depths and we came to a similar conclusion and blade profile. Interesting on how they triangulated the spokes as well.

Thanks!

Rob Beckers

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Re: 5kw Poncelet Wheel Project
« Reply #263 on: December 13, 2017, 07:28:34 AM »
Skid, did you sort out the oscillation issues with the inverter? Where the load on the turbine would bounce up and down. Just curious if you ever tracked that down.

-RoB-