Having just got my big drum home , I'm now having a bit of a think.
Heres the plan at present.......
The most head I have to play with is 8 ft , so a 6 inch pipe down the small creek bed and then rising up to feed the top , or maybe a wooden flume.
Overshot wheel, It will be 6 ft 6 inches diameter and I'm going to cut the width down from 1.4 metres to about 500mm (20 inches) and weld 22 curved buckets
It will be driving a F&P smart drive motor to charge a battery bank invert etc etc, probably using chain then v belt to give about 50:1 at I reckon about 10 rpm at the wheel.
I'm still tossing up the mounting but I'm leaning towards using a trailer stub axle on each side and mounting the sprocket to the wheel, rather than a shaft through the wheel and taking the power off the shaft.
At 30 litres a second It could produce 150 to 250 watts output for about 9 months of the year so worthwhile in my book
Any thoughts appreciated
Cheers
Keith
Sounds like a fun project, looking forward to more pics and updates!
Don't let fisheries find out.
The spindles/hubs should work ok, as long as they are in line. If I were you I would mount the rotor in place first. Then you could make up a basic brake dyno to measure the sustainable torque and RPM output of the rotor in operation. Knowing that would make the gear ratio and generator choice a lot easier...
I'd go for the flume. I "think?" that you'd get a bit more out of it using both the velocity and fall of the water, but I'm no hydro expert.
I must say I like flumes too ,I'll probably end up using a bit of both.
A little update.
Progress is slow due to weather ,other projects and my general slackness. But I managed a few hours with a skillsaw and some abrasive blades and made a small start.
Internal width will be just over 400mm so I can cut up the centre section to make all the buckets
Hi KeithO,
I've never seen one of those huge wire spools I didn't want. And plastic is pretty easy to work with - part of the lure for me.
I'm just thinking that looks like a lot of mass to move for 2-300 watts. How many watts do you think it will take to move it?
Casey
Care to share how you scored that nice spool?
Quote from: LowGear on September 15, 2010, 11:42:09 AM
Hi KeithO,
I've never seen one of those huge wire spools I didn't want. And plastic is pretty easy to work with - part of the lure for me.
I'm just thinking that looks like a lot of mass to move for 2-300 watts. How many watts do you think it will take to move it?
Casey
That spool appears to be made of steel & they sure aren't cheap. They charge us about $600.00 when we don't return one.
SR
Holy Moly,
I just blew up the photos. I think you're right about it being steel. What a project! More mass than I dreamed of. I guess once it gets going round and round it wouldn't require any more mass that Styrofoam? I say "I guess?"
Casey
Yes it is steel , just over a ton.
It used to have heavy steel wire rope on it , i managed to get it before the the scrappers took it ;D
In remote areas shipping them back empty costs more than they are worth.
Keith,
That looks like a kewl project. Please keep us updated on your progress!
Will do.
I had a hold up when my generator and buzz box wasn't cutting the mustard on 5mm steel.
I have been loaned a huge old Deutze powered Millar welder. (I'll cry when I have to give it back)
Ive done 7 of the 22 buckets so far and scrounged a 55mm axle and bearings.
Will post some pics when my camera comes back from holidays.
Cheers
Keith
Progress pics
All buckets fitted and welded on back / outer side ,
Should have the inner side done in a day or so
Next step, the axle
I have rethought the siting on the creek to a place more accessible and shorter penstock but with a slightly lower head and so will have to change to a pitchback configuration.
Looking really good there KeithO!
Holy Cow ! What a beast, I love it.
Don't know how I missed this thread. This is awesome!!!
Somehow I missed this thread as well.
I really like the look of waterwheels and I also like that they operate at low RPM (typically 5-15 RPM). However, while it's clearly true that a waterwheel can exert a lot of torque, their ability to generate power (i.e., their ability to do work over time) is severely limited by this low RPM.
0.000253 x flow rate (in GPM) x waterwheel diameter (in feet) x efficiency (%/100) = mechanical horsepower
The constant (0.000253) is the water weight of 8.35 pounds per gallon divided by 33,000 foot-pounds per minute (i.e., the definition of one horsepower).
So one would estimate an 8' diameter well-designed, over-shot, waterwheel (80% efficient) being fed 30 liters/second (476 GPM) would generate about 0.77 HP (574 watts). One will likely lose 25-30% converting this mechanical power to electrical power, so one would expect to be able to generate about 400 watts of electricity. If 6' diameter, one would expect to be able to generate about 300 watts of electricity.
Of course, the aforementioned assumes that the waterwheel can "digest" being fed 30 liters/second (i.e., all the water produced by this flow rate stays in the buckets and goes along for the ride from the top to the bottom at the operational RPM). So, for a given waterwheel bucket volume and operational RPM, one would expect there to be a maximum flow rate that the waterwheel can digest...beyond which, more flow rate won't produce any more power. Or worse, one won't obtain the aforementioned power because the waterwheel bucket volume won't be able to digest 30 liters/second.
Lets try to figure this out... Lets assume the operational RPM is 10 RPM. The water doing the work only travels half the rotation.
0.5 times 10 RPM divided by 60 seconds per minute equals 0.083 RPS
30 liters/second divided by 0.083 RPS equals 361 liters per rotation
So I am thinking the waterwheel total bucket volume has to be at least 361 liters to digest 30 liters/second. Or each bucket has to be at least 361 liters divided by the total number of buckets.
Bob B.
what an awesome project!
wow, i am green with envy at having the resource, and the ability to construct such a beast
very cool
bob g
Thanks for the support guys, I appreciate it a lot. ;D
Bob B ,Your power numbers stack up with mine though I am being conservative with efficiency to keep my expectations down .
I 'm looking for 200 - 250 watts for a start as we have quite low electrical usage. ( lpg cooker ,coal boiler)
As far as volume the wheel will handle, treating each bucket as a straight triangle and ignoring overlap works out to:
15.5 ltrs x 24 buckets =372 ltrs per rpm x 10 rpm = 3720 ltrs /60 = 62 ltrs sec
So 30 lts sec should give a low spill point at 10 rpm, though a higher rpm will work and reduce wear and tear on the drive line.
As usual it will all depend on gearing and generator cut in speed
Cheers
Keith
Hi Keith,
Sounds like you are golden and this should work very well for you indeed. I am very much looking forward to more photos and perhaps a video when you bring her to life!
BTW, and certainly not critical for this slow RPM project...whenever one builds rotating machinery (e.g., a Banki crossflow turbine), it is best to use a "prime number" of rotating elements whenever practical. Here are the prime numbers below 100:
2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97
This improves balance and minimizes the potential for harmonic body bending mode combinations that can lead to noise, vibration, and ultimately fatigue failure.
Bob B.
Progress pics
ratio is 33:1
Now THIS is a labor of love!!
Holy cow!!! That looks like a ton of work (literally) to make 2KW a day.
I love the shape. I can't wait to see a video of it in work.
Great, just great, I now have to clean the keyboard of the other computer that I drooled all over !
KeithO,
Is that 'alternator' a modern washing machine pancake motor? I've only seen a removed stator from one, many poles. Is the rotating armature a permanent magnet jobby?
That is a terrific project you are tackling there IMO. I actually saw an exact same type metal reel the other day free for the taking. I recognized it immediately having followed this thread. Unfortunately it could not follow me home, too heavy for my car's roof rack. >:(
I too think this is an AWESOME project!
One question, not sure about the belt driving the alternator. With that small pulley, I'm concerned it will slip once a load is put on it. Just my $.02...
I'd love to have the water resource to build a project like that!
Fantastic job!
Steve
Cheers guys
Hi RCA
The alternator is a motor from a Fisher and Paykel smart drive washing machine.
That one has 1mm windings (aka 100) but I have a couple of others 0.8 (80)
The grey plastic rotor/cover has permanent magnets on the inside.
The wiring can be reconfigured many different ways
See here http://www.thebackshed.com/Windmill/FPRewire.asp (http://www.thebackshed.com/Windmill/FPRewire.asp)
LG also make a similar one
I know what you mean about the reel , not so easy to move.
Steve
Hopefully the pulleys will do the job , they were both taken from a water pump that used a motor of about the same size hp as I am hoping to generate , admittedly at a higher speed though , we shall see I guess.
Have you filled the buckets to confirm that you capture enough water weight to create enough torque to overcome the friction, static inertia and gearing so as to be able to get everything turning?
Here's an interesting water wheel website:
http://www.waterwheelplace.com/water_wheel_electricity.html
Bob B.
Hi Bob B
Good question , no not yet as the buckets aren't sealed .
The cool thing about water wheels is their start torque.
If we apply the water supply it fills the top bucket and the cascading water fills those below it.
I stopped a 4 ft breast shot by hand in the past and received that lesson.
If we assume that the equivalent of a quarter of the wheels buckets fill at standstill we get 93 kg or about 205 lbs of water at roughly 3 ft of leverage , so thats 615 ft/lbs at the shaft.
That divided by the 33:1 drive ratio gives us 18.6 ft/lbs at the notorious badly cogging smartdrive alternator.
Should be fine.........
I'll look into it though as it is good to have the numbers
Another good calculator for playing with water http://www.calctool.org/CALC/eng/civil/hazen-williams_g (http://www.calctool.org/CALC/eng/civil/hazen-williams_g)
Keith,
What is the status of this project? Is it alive with perhaps a video to show?
Bob B.
Hey Keitho. howzit going Boss? Where did you find your F & P ? I have a .8mm on an old Anderson engine. These motors are just the Biz and can really poke out some ergs at very low revs. I got a couple for free (broken down trade-in washing machines - heaps in NZ) and the most expensive part of the job was the tiny pot of eurethane to insulate the joints and windings after the soldering. Even the bridge rectifiers (3 x 35 amp) were only about $4-00 each. Once fellow members get into these units and realise how cheap and easy they are to deal with, they will be real popular. Just set up your revs (constant) to poke out voltage required and no further regulation required. Looking foward to seeing more pix. Cheers, Derb.
Hi guys , Its still slowly progressing.
Due to difficulties in manhandling it , I couldn't site it down the creek far enough for a high water entry point
so it is now a breastshot.
I will have to put up with lower output as the buckets were not built for this configuration .
Thats the price I'll have to pay for changing horses mid stream :-[
Anyway its sitting in position , unfinished and grubby , as is the flume although the supports are very temporary and it will be a bit of a race to get it all framed up before the rain arrives.
Here is a video of its present state at late autumn (driest time of the year) that my daughter made for me.
So its just turning , making 20 watts or so
Nice one Keitho. Out there doin it. :) Good to see it with a bit of flow come the rains. Cheers.
Cheers Derb,
We are north of Westport NZ , so when it starts raining you know we are going to get a fair bit of it .
Average is about 6 ft a year
Rain has arrived Yay....
Flume is holding up OK
So only higher sides on the forebay , proper generator enclosure and clean and paint for the wheel to do.
Its producing a constant 145 watts 16.5 RPM even with the forebay spillage and a bit of backwatering
So I'm relatively happy that it has potential to produce more.
Thats enough even now to run our house.
Hey Keitho. What voltage you running at? Are you using the existing F and P bearing assy or using pillow block set up? I cleaned off all the plastic from the alloy brg housing and set it inside a piece of box section by pouring epoxy resin into the cavity around the housing. (after welding my mounting bkts to the box 1st) Now looking for a cheap 24v inverter. The magneto on my old Anderson was toast so I have fitted a cam and contacts to the mag sprocket shaft and can run the car coil straight off the DC side of the PM generator. (at present am running the setup at 12v via gearing/revs) I have since found an earlier Gentle Annie motor which is more akin to an old 1/4 hp motor in size which I am fitting to a morrison exercycle for the missus. These units have a much friendlier mounting configuration and are easier to draw off your tappings.(no soldering required) Cheers Boss.
Hi Derb
Its running at 48v nominal v
The bearing mount is the standard f&P alloy mount , I just threw it in a fire and burned the plastic off.
Then made some U bolts out of 6mm stainless allthread to mount it.
Gentle Annies
You have got two sets of three phase windings
these can be wired in parallel by jumpering on the standard plug for a better output
But what I found was if you can separate the Wye connections and bring them out on separate leads, then series wire the two windings and rectify each phase with a bridge rectifier separately then you will get more output at low power inputs.
ie little water wheels
I think its called jerry rigging on http://www.fieldlines.com
This probably needs a drawing ...
let me know if you want to have a go
Wow!
After watching the first video I wondered how much could 4" PVC cost and then the second video showed me you'd need something a lot bigger than 4". I then wondered how much you were losing because of the 90 degree turn just before the wheel? Would it make a difference if the water fell from above the wheel flowing in the same direction as the wheel? I was curious that you used a chain drive rather than both pulley systems being belt?
Don't get me wrong. I've been screwing around with a centrifuge drying system for over a year so another Wow for your hard work and accomplishment.
Casey
Hi Casey
The wheel is sitting in a natural notch in the creek bank on inside of a 90 deg bend in the creek away from flow during summer flash floods.
It was originally going to be facing the other way with the water being fed over the top further down the creek but the reality of moving it by hand down the creek bed changed my mind :-[
So I have to put up with the lower entry point it has now, the water has to decelerate to drop at the correct angle into the buckets , or you'd lose power from the water slapping into the underside of the descending buckets so i don't think I'm losing too much in the corner.
There is a study on Breastshot performance here https://docs.google.com/viewer?a=v&q=cache:XV1ouI6CJpwJ:steffenreichel.homepage.t-online.de/Muehlen/Infos/ModernWaterwheels.pdf+&hl=en&gl=nz&pid=bl&srcid=ADGEEShGzgYHPO-0LxHgVmQTtAqjd0uRUo3LOO8Fog7zSeplH3TCzGWoOMOHdBIXtOcpa-m2SYWOLHjtmNBB-3LXqbHN5nYuMOdkgL6B4L0OLZekCJEA1XQPb6d7ZAKB7ZG1zDMlhymj&sig=AHIEtbSwSQDbB58vdGQ3WyyPKZufts4ggg (https://docs.google.com/viewer?a=v&q=cache:XV1ouI6CJpwJ:steffenreichel.homepage.t-online.de/Muehlen/Infos/ModernWaterwheels.pdf+&hl=en&gl=nz&pid=bl&srcid=ADGEEShGzgYHPO-0LxHgVmQTtAqjd0uRUo3LOO8Fog7zSeplH3TCzGWoOMOHdBIXtOcpa-m2SYWOLHjtmNBB-3LXqbHN5nYuMOdkgL6B4L0OLZekCJEA1XQPb6d7ZAKB7ZG1zDMlhymj&sig=AHIEtbSwSQDbB58vdGQ3WyyPKZufts4ggg)
Mine resembles what they did in figure 8
I had thought of going tooth belt for primary drive but chain and sprockets are easier to get out here in the sticks.
Cheers
Keith
Outstanding there Keith. Outstanding!
That's a very impressive job, Keith. I could get along quite nicely on your output. Enjoyed your videos and following along with your progress, thanks!
I could sit there and watch that wheel spin all day. ;D
Thank's for posting Keith ;D ;D
Quite the project and I am very happy to see it is working nicely!!!
Your current breastshot configuration is only producing about 50% of the power that we estimated the planned overshot configuration would produce...which makes perfect sense since we are only filling about 50% of the buckets we had planned on filling (and we are only using 50% of the head we had planned on using). We should try to improve this!
Your penstock water flow velocity (i.e., feet per second) currently feeding your wheel appears to be way more than adequate! What did the volume of your buckets turn out to be and how many do you have on your wheel? What percentage of the bucket volume is currently getting filled by the flow rate (i.e., cubic feet per second) that you are now feeding the wheel at your operational RPM?
I guess where I am going with these questions is to determine the feasibility of trying to raise the water entry point and also increase the penstock channel cross-sectional area (i.e., increase the penstock wall height) so as to generate adequate flow rate to completly fill the bucket volume and also fill more of the higher buckets. Just increasing the entry height alone will reduce the flow velocity and also reduce the flow rate if you don't ALSO increase the penstock channel cross-sectional area (i.e., Q=VA). So you need to "optimize" your penstock cross-sectional area AND your entry height given your wheel location and given the optimal flow rate your wheel requires based on it's operational RPM. However, please also keep in mind that increasing the penstock channel cross-sectional area will also increase the weight of water that the penstock will have to be able to structurally handle and this would have to be properly dealt with too. So the goal here is to generate just enough flow rate to completely fill as many high buckets as possible without having too big a penstock that is not feasible to build.
If you know the optimal flow rate your wheel requires (see my previous posts about this), you could use this "Ditch calculator" link to optimize your penstock cross-sectional area AND your entry height so as to get this optimal flow rate:
http://www.wrd.state.or.us/OWRD/WR/cwre_info.shtml
I would suggest using 0.012 (i.e., wood channel) for the "n-factor" Manning's roughness coefficient.
Bob B.
Thanks for the supportive comments guys , I love these forums
Hi Bob B
I agree , the output is at present Okay at best.
The first changes are to double the height of the forebay flume walls
Then sort out the tailrace , the buckets were dragging through about two inches of water in the second video , not good
The bucket filling vs rpm question is an interesting one.
I thought 16.5 rpm was a bit fast , but with the buckets only having a capacity of roughly 15.5 litres and only using a quarter of the 24 , we have
6 buckets x15.5 ltrs x 16.5rpm = 1534.5 ltrs or 405 US gal per minute dropping 3.5 ft @.55 eff should give us 147 watts
Obviously I need to speed up the wheel a little , easily adjusted with the F&P generator , and the removal of backwater will help.
As for lifting the entry height , I think that might be getting into the area of diminishing returns , my designs for vanes to match the water angle to the wheel for a backshot always seem workable on the kitchen table , but not so easy when I'm standing in the creek
Cheers
Keith