Pelton starting question...

[iPanos]

Hey guys,

After a lot of reading, I am now passing into the actual experimentation with my project.

Hoping that I have made the right decision, I am going for a pelton wheel. I have found a 280mm diam wheel which I believe will be a good start for my site. I estimate a flow of about 100l/min and a 50+ m of head.

Please let me know what you think of this. Although I will be starting with this turbine (cos I have it available), do you think for my flow/head there is a more ideal kind of setup (i.e banki, different diameter pelton etc...) ?

Last, I have a problem selecting my nozzles. I will build my enclosure for 2 or 4 nozzles, and test it to see how many will produce the best results. I have a feeling that 2 will be good. Can you please advise me on what orifice diameter I should go for (given that 2 of them will run at the same time)?

Thank you and let me know of your thoughts, or if I have gotten something wrong without realising...

[XXLRay]

Many people use peltons with worse data. So I think you will be just fine with it.

I think an uneven amount (e.g. three) of noozles keep the forces more ballanced.

[iPanos]

Thank you for this!

Please anyone could advice on the nozzle diameter, I am really looking forward to order and start testing...

Thanks...

[hydrosun]

A 1/4th and 3/16th inch nozzles combined will let out about that amount at the head you specified. I don't have the metric conversion for you. The size of the pelton will effect the rpm the turbine turns and you will need to have an alternator that puts out the voltage you want at that speed.  A smaller pelton (120mm) would easily handle the amount of water you indicate and spin much faster (2300 rpm at your head) Your pelton would turn about 1000 rpm at load. Your description of 50+ meters head gives a large amount of uncertainty to any calculation.   Put in a pipe and see what the pressure gauge reads to pin down what is the exact head to help design the best system.
Chris

[iPanos]

Very interesting! Thank you very much for the information, all that rpm sounds more than i was hoping for...

So, when you say "A 1/4th and 3/16th inch nozzles combined" (for reference that should be 6.4 and 4.8 mm respectively), do you really mean one of each? So I will have a design with two different nozzles running simultaneously? I have a feeling I am getting something wrong...

Thanks again...

[hydrosun]

Your original message said you wanted to have two nozzles. Having different size nozzles allows you to vary the amount of water used to three different levels. Small nozzle alone, large nozzle alone and both together.  The amount of water isn't enough to effect balance when using different size nozzles.  If you want only one nozzle you could use a 5/16th inch opening to approximate your design water flow.
Chris

[iPanos]

It is clearer now, so far at least! Thanks for the enlightenment...

I have already 2 nozzles of 4mm which I am thinking to use as a starting point. Also, following the suggestion of hydrosun's first post here, I will machine a smaller axis and use some of my wheel's spoons to make a 120mm as well (my wheel has removable spoons). I will test with both wheels and see results. Then I will try to optimize the nozzles and the rest of the system.

[Ungrounded Lightning Rod]

It is clearer now, so far at least! Thanks for the enlightenment...

I have already 2 nozzles of 4mm which I am thinking to use as a starting point. Also, following the suggestion of hydrosun's first post here, I will machine a smaller axis and use some of my wheel's spoons to make a 120mm as well (my wheel has removable spoons). I will test with both wheels and see results. Then I will try to optimize the nozzles and the rest of the system.

Figure that at the static pressure the water would leave the nozzle at the same speed as if it fell the length of the head - and you have to derate that for the pressure drop for friction with the penstock plumbing.  (Table available for pressure drop vs pipe size and flow rate.  Jet velocity is proportional to square root of pressure.)

Peltons run with the wheel at the water-impact radius turning just under half the speed of the water jet.

Combine all that with your desired RPM and you can compute the radius at the centers of the pelton spoons.

Combine all that with your