Author Topic: Speed of Banki Turbine  (Read 26066 times)

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Harold in CR

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Speed of Banki Turbine
« on: August 18, 2010, 09:25:38 AM »

 I have read a lot of threads about the Banki Turbines that were built and used. I have never seen info on the RPM's available ??  Has anyone ever taken readings of the RPM's ??

 I have a neighbor, with 60 GPM of water at 30' of fall. YES, I did measure with the 5 gallon bucket shoved under the 4" outlet pipe in the concrete dam.

  I have studied several designs of Mitchell-Banki turbines, and have decided to try the Ossberger design. It fully utilizes ALL the water from the input, unlike most homebuilt units, that spray water over the top of the turbine.

 I am thinking about using an alternator at 2KW. It will be self excited, so, no need for external excitation. The Alternator is 1800 RPM rated. Gearing is possible, although I would prefer to not have to use it, if possible.  An induction motor, at under 1000 RPM's, might be another option. Would need to apply external voltage, maybe a 12 Volt battery and inverter ??, to excite the motor, once up to speed ??  Is this even possible ??

 I am trying to design a water control device, to regulate the cycles or voltage to keep within the 120-240V range. So far, a governing device has not been decided on. I was thinking about a linear actuator, that would open and close a sliding valve, or, open and close a ball valve. It would need to be activated by the Alternator, with an electronic monitoring device. It may be a little slow to operate, but, should work well, with plenty of power.

  According to my calculations using several different calculation sites, there should be between 1-2 KW of power available, IF I can control every drop and use the governing system.

 Anyone feel like commenting on this project ??

XXLRay

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Re: Speed of Banki Turbine
« Reply #1 on: August 18, 2010, 11:20:59 AM »
Rounds[1/min] = (Waterspeed[m/s] x 60s) / (2 x PI x Banki-Radius[m])

Ungrounded Lightning Rod

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Re: Speed of Banki Turbine
« Reply #2 on: August 18, 2010, 11:53:56 AM »
Rounds[1/min] = (Waterspeed[m/s] x 60s) / (2 x PI x Banki-Radius[m])

I think that's wrong.  It looks like you're assuming the banki spins with the edge at the speed of the incoming water.  (TSR = 1 in wind turbine speak.)  That would be right for an optimized overshot wheel, but...

As I understand it a crossflow slows the water by only about 50% as it enters and another about 50% as it leaves, so cut that in half.  (TSR = 0.5)  Then take it down a tad more.  (The mill isn't 100% efficient and the water needs some velocity when it leaves.)

(Also:  Note that "waterspeed" is the speed of the water as it leaves the jet.  Figure that as the speed it would be traveling if it had fallen from the height of the head.)
« Last Edit: August 18, 2010, 11:56:38 AM by Ungrounded Lightning Rod »

damian

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Re: Speed of Banki Turbine
« Reply #3 on: August 18, 2010, 02:27:49 PM »
Just to try to get a handle on the power available, somebody please correct me if I'm wrong here, but my math looks like this:

60 GPM x 8.3 lbs./gallon = 498 lbs./minute x 30 feet = 14,940 ft. lbs./minute

1 Kw = 44,253 ft. lbs./minute

So power available is 14,940/44,253 = 0.3376 Kw

That is the total, less efficiencies of all components.

So maybe shooting for 100-200 watts is more realistic?


Damian


Harold in CR

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Re: Speed of Banki Turbine
« Reply #4 on: August 18, 2010, 05:53:45 PM »

 YUP, yer correct. I messed up the conversions.  :-[ :-[ :-[

 The Ossberger states up to 80% efficiency is VERY attainable. Still not a lot of power, though.  ::) ::)

damian

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Re: Speed of Banki Turbine
« Reply #5 on: August 18, 2010, 09:36:20 PM »
Well, on the other hand, hydro is 24 hours per day, seven days a week.

0.2 Kilowatts x 24 x 30 = 144 Kwh/month.

Damian

XXLRay

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Re: Speed of Banki Turbine
« Reply #6 on: August 19, 2010, 04:13:04 AM »
I think that's wrong.  It looks like you're assuming the banki spins with the edge at the speed of the incoming water.  (TSR = 1 in wind turbine speak.)  That would be right for an optimized overshot wheel, but...
You are absolutely right. I totally forgot to add the speed factor. After some research I found out that it seems to be 0.45 for crossflow turbines like banki/ossberger are. Thus the formula should be:

Rounds[1/min] = (Waterspeed[m/s] x 60s x 0.45) / (2 x PI x Banki-Radius[m])

Harold in CR

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Re: Speed of Banki Turbine
« Reply #7 on: August 19, 2010, 07:25:48 AM »

 Does anyone know how to size one of these things, to take full advantage of the water supply ??

XXLRay

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Re: Speed of Banki Turbine
« Reply #8 on: August 19, 2010, 09:00:00 AM »
You need to know Head, Water-Throughput and the rotational speed of your generator. All in metric values for the following formulas. Just paste your data and calculate your way through.

Head[m] = measure!

Throughput[l/s] = measure!

Generator-Rounds[1/min] = measure!

Crossflow Turbine Spinfactor = 0.45

Water-Speed[m/s] = √(2 x  Gravity[m/s²] x Head[m]) = calculate!

Banki-Radius[m] = (Water-Speed[m/s] x 60s x Spinfactor) / (2 x PI x Rounds[1/min]) = calculate!

For the noozle:

Noozle-Area[m²] = Throughput[m³/s] / Water-Speed[m/s] = Throughput[l/s] / (Water-Speed[m/s] x 1000) = calculate!

Banki-Circumfence[m] = 2 x PI x Banki-Radius[m] = calculate!

Noozle-Length[m] = Banki-Circumfence[m] / 4 = calculate!

Noozle-Width[m] = Noozle-Area[m²] / Noozle-Length[m] = calculate!

I don't know how to calculate the amount and size of blades. Perhaps someone else can provide the formulas.

robl

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Re: Speed of Banki Turbine
« Reply #9 on: August 19, 2010, 06:32:22 PM »
All the formulas and a set of Excel macros can be found on the "micro-hydro power" group on Yahoo. It also has a pdf of the original design manual of the Michell-banki (Ossberger variant). I have been running a 22 runner Banki turbine for about 20 years. Width is 7", diameter is 12", turbine rpm is around 300. Gearbelt drive to 1200 RPM induction motor running C/2C. Output is around 650 watts/240V/60HZ with about 20 feet of head. Don't recall the GPM's. I have a short (and crappy) video of the rig here:  http://www.youtube.com/watch?v=_xn1cz3F4Q0

Regards

Rob

ghurd

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Re: Speed of Banki Turbine
« Reply #10 on: August 19, 2010, 06:43:48 PM »
I have a short (and crappy) video of the rig here:  http://www.youtube.com/watch?v=_xn1cz3F4Q0

Regards

Rob

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robl

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Re: Speed of Banki Turbine
« Reply #11 on: August 19, 2010, 07:06:02 PM »
Thank you Ghurd,

Just for the record, it was this group that helped me convert to the induction generator a few years ago. Prior to that the rig was powering an ancient 1200 RPM 120VDC compound wound dc motor.

Rob

Harold in CR

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Re: Speed of Banki Turbine
« Reply #12 on: August 19, 2010, 08:47:05 PM »

 AhhhhhhHAAAAAaaaaaaaaaaaaa  8) 8)  This is exactly what I have been looking for. Youtube is not a reliable viewing source, with my limited Internet access.

 You have provided MUCH info for me, and your video was perfect for me to try to replicate your turbine.

  Did you put in a flow divider, like the Ossberger, to split the flow or input water, to get more fins in contact with the water ??  Did you build the nozzle like the Ossberger, to MAKE the water build a slightly more pressure, as it runs around the inside of the housing ??

 Could you elaborate a little on how you rigged up the motor as a generator ??

  This is exactly what I want to carry around and set up at various locations, to actually measure the amount of power I can obtain at different areas along a stream.

  THANK YOU for posting this info. I really appreciate your knowledge and input.   Harold

XXLRay

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Re: Speed of Banki Turbine
« Reply #13 on: August 20, 2010, 02:56:21 AM »
It hink the pdf is "The Banki Turbine" by C. A. Muckmoore and Fred Merryfield http://agungchynta.files.wordpress.com/2007/03/crossflow-turbine.pdf

XXLRay

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Re: Speed of Banki Turbine
« Reply #14 on: August 20, 2010, 07:34:36 AM »
You might also find important information in "Blade calculation for water turbines og the Banki type" by P. Verhaart: http://alexandria.tue.nl/repository/books/19153.pdf

Harold in CR

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Re: Speed of Banki Turbine
« Reply #15 on: August 20, 2010, 08:30:53 AM »

 You guys just don't realize how much help  you are.  I don't speak "Computereze", so, when I search, I NEVER get the results y'all get.

 I am drawing out the type of Turbine I will build, and, when I have it working, will post every bit of info on here.

 Now to find info for the most efficient-durable generator. Battery systems are more costly. AC systems are more technical. Some situations may require one or the other, so, back to searching.

 I expect to test many streams at many locations, so, accurate flow rates and output will be recorded.

  THANK YOU to all those that take the time to help us less "Computerized" folk.

  XXLRay, excellent links. Thanks ALL  8)

jlt

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Re: Speed of Banki Turbine
« Reply #16 on: August 20, 2010, 10:13:02 AM »
http://h-hydro.com/index.html You might look at this site It has info on expected rpm and output power. although It is not a banki turbine It would work for you.

Harold in CR

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Re: Speed of Banki Turbine
« Reply #17 on: August 20, 2010, 01:28:40 PM »

 Thanks. That site I have bookmarked and have used their calculator.

robl

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Re: Speed of Banki Turbine
« Reply #18 on: August 20, 2010, 02:38:31 PM »

 AhhhhhhHAAAAAaaaaaaaaaaaaa  8) 8)  This is exactly what I have been looking for. Youtube is not a reliable viewing source, with my limited Internet access.

 You have provided MUCH info for me, and your video was perfect for me to try to replicate your turbine.

  Did you put in a flow divider, like the Ossberger, to split the flow or input water, to get more fins in contact with the water ??  Did you build the nozzle like the Ossberger, to MAKE the water build a slightly more pressure, as it runs around the inside of the housing ??

 Could you elaborate a little on how you rigged up the motor as a generator ??

  This is exactly what I want to carry around and set up at various locations, to actually measure the amount of power I can obtain at different areas along a stream.

  THANK YOU for posting this info. I really appreciate your knowledge and input.   Harold


Hi Harold,

I don't have much time at the moment for details but I will try and hit the main points...

I did not divide the wheel or the nozzle. this was a mistake that I will hopefully have time to revise in the next iteration.

The nozzle does scroll slightly to increase and focus the water jet on the blades. I put Lexan on the sides during testing and can confirm the water hits the blades twice. I have also added a draft tube out plywood about 2 feet long as an experiment. It seems to be working OK.

The motor is now a 1hp 3-phase 1200 RPM (was a Y-wound 1800 RPM in video) running in delta mode, wired to put out single-phase 240/60 HZ.  The wiring of the capacitors to do this is a bit complex to explain in a message. best to purchase Nigel's book on the matter from Amazon. I will look up the full title for you if you wish. There is a 9 volt battery, diode bridge and switch in the circuit to pre-magnetise the coils before start-up after a long shut-down. The TRIAC load dump circuit has now been replaced by two simple voltage relays that disconnect the load as the wheel spins down (to preserve the magnetising current) and switches in the base board heater only if a no-load/runaway condition occurs. The real working load dumps are at the 2 homes where they can heat hot water.

I would suggest there are simpler ways to measure the potential of a stream rather than carrying a Banki turbine about - unless you have tractor/backhoe access to your test points. Without the concrete spillway or draft tube my unit comes in about 150 pounds, including the generator...

Regards

Rob

Harold in CR

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Re: Speed of Banki Turbine
« Reply #19 on: August 20, 2010, 04:22:51 PM »

 Thanks Rob. If you ever get time, I can be patient.

 I found a site, where a guy has developed a Banki type system, that can produce multi hundreds of KW's, and, the Turbine is not really all that big. Looks like 6" wide X 24" or so high. He developed the After Burners on RR Jet engines, and used "Torque Tubes". He also used them in his Turbine design. I'm investigating that concept, before I start building. He claims much improved forces striking the blades. ??

 Thanks again.  Harold

Ungrounded Lightning Rod

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Re: Speed of Banki Turbine
« Reply #20 on: August 21, 2010, 01:33:59 AM »
These are good links.  Let's add them to the FAQ

Harold in CR

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Re: Speed of Banki Turbine
« Reply #21 on: August 21, 2010, 12:26:06 PM »

 Have at it. I know nothing about how to do that.  If I need to be the one, coach me. I have no problem with it.  8) 8)

Harold in CR

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Re: Speed of Banki Turbine
« Reply #22 on: August 21, 2010, 03:49:19 PM »

 Link to site with Video about the Torque Tube Water turbine. Wish I could see inside, EH ???

http://libertyisgreen.com/index.php?topic=37.0

XXLRay

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Re: Speed of Banki Turbine
« Reply #23 on: August 28, 2010, 04:08:37 AM »
I recently found a banki turbine calculation excel sheet on the web: http://gregrichter.com/TURBINE.xls

Harold in CR

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Re: Speed of Banki Turbine
« Reply #24 on: August 28, 2010, 08:57:26 AM »
 Thanks for that info.  I recently obtained 2 saw blades, that are 12" Dia. X nearly ¼" thick. Cut the teeth off at the gullets and trued the plates up on my Wood lathe using my side grinder. VERY little vibration at this stage. I will be sawing logs today, but, will be cutting blades tomorrow.

 Need to take the camera to the shop, and get photos.

 It's NOT too late for ANYONE to add their 2 cents-pesos-centavos-yen, or whatever type input you may have.

 Thanks for all the input, so far.

 DAMN, Can't open the link. Don't have Excel on this computer. Anyone know of a 30 day trial program I can use to open this .xls ???
« Last Edit: August 28, 2010, 09:01:50 AM by Harold in CR »

DamonHD

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Re: Speed of Banki Turbine
« Reply #25 on: August 28, 2010, 09:03:16 AM »
OpenOffice is free and will open Excel .xls files.  It's what I use.

Rgds

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TomW

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Re: Speed of Banki Turbine
« Reply #26 on: August 28, 2010, 09:18:31 AM »
OpenOffice is free and will open Excel .xls files.  It's what I use.

Rgds

Damon

Yeah, same here.

Best of all it is free.

And it is available for Linux, Mac and The Redmond users (MicroSoft).

Works great, less filling. ;D

Tom

Harold in CR

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Re: Speed of Banki Turbine
« Reply #27 on: August 28, 2010, 01:37:01 PM »

 Thanks guys. I will get it.  8)

tanner0441

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Re: Speed of Banki Turbine
« Reply #28 on: August 28, 2010, 04:34:25 PM »
Hi

Google Reaction Turbine and you get to look inside the box with the four shaped jets and a description of how it works....

Brian

Ungrounded Lightning Rod

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Re: Speed of Banki Turbine
« Reply #29 on: September 03, 2010, 03:55:26 PM »

 Link to site with Video about the Torque Tube Water turbine. Wish I could see inside, EH ???

http://libertyisgreen.com/index.php?topic=37.0

Here's a Link to the patent.

Harold in CR

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Re: Speed of Banki Turbine
« Reply #30 on: September 03, 2010, 05:23:20 PM »

 Good Find. Thank You.  ;D

hydrosun

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Re: Speed of Banki Turbine
« Reply #31 on: September 09, 2010, 12:20:31 PM »
I'm a bit confused. This thread started with a site with 60 gpm and 30 feet drop. A relatively simple 4 inch pelton can handle that situation easily. An off the shelf solution from Harris or ESD or plastic spoons from Joe Hartivgsen at h-hydro.com to make your own pelton wheel. Why make a large Kaplan turbine for only 60 gpm?
Chris

Harold in CR

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Re: Speed of Banki Turbine
« Reply #32 on: September 09, 2010, 02:48:13 PM »

 Shipping and import duty fees. Also, guy decided to go further down the hill, AND, that 60 GPM is minimum. 2 months of the year that's the max output. Rest of the year, he gets nearer to 100 GPM.

 In this case, let's make juice while it's raining.