Weight of the runner has no effect on its efficiency except for a slight increase in bearings' frictional loss (due to added weight). Smooth bucket materials and those resistant to corrosion minimizes the losses due to surface friction. Plastic buckets usually have better smoothness, but you have to consider carefully its application since it is easier to abraid (caused by silt suspended in water) as compared to bronze and stainless buckets.
[EMAIL PROTECTED] wrote: Some great info here. Question: What effect does the material that the buckets are made of and total weight of wheel have in correlating to loss of effeciency? Don A. -------------- Original message -------------- > Hi Sergio. > > Some useful links: > > http://www.tev.ntnu.no/vk/publikasjoner/ > A textbook for students on hydro power machinery. > http://www.tev.ntnu.no/vk/publikasjoner/pdf/ArneKjolle/chapter2.pdf > http://www.tev.ntnu.no/vk/publikasjoner/pdf/ArneKjolle/chapter3.pdf > Detailed theory with formulas for many types of turbines. > > http://www.microhydropower.net/ > Good general explanation of the Pelton turbine with pictures. > http://www.microhydropower.net/turbines.html#Pelton > > http://en.wikipedia.org/ > Wikipedia, the free encyclopedia that anyone can edit. > http://en.wikipedia.org/wiki/Pelton_wheel > > http://www.ecoinn.co.nz/ > Very well made runners with plastic spoons, excellent pictures. > http://www.ecoinn.co.nz/product_detail.php?id=58 > > http://www.pressure-drop.com > Software to calculate pressuredrop for all kinds of fluids, pipes, > fittings, nozzles, etc. > You can test it 4 weeks free. If you want use the program after this time > you have to register by the author. > > Pressure-Drop can be used to find nozzle diameter (by trial and error). > (I have not searched for a jet diameter formula based on pressure and flow). > > http://www.du.edu/~jcalvert/tech/fluids/turbine.htm#Impu > Good explanation of Pelton turbine with formulas. > > Summing this up: > Bucket size approximately 2,5 - 4 times jet diameter. > (Too small buckets do not use all the water efficiently, > but too big buckets create more aerodynamic drag) > Water exit angle approx. 165deg (so the water does not hit the back of next > bucket). > The edges where the jet hits the buckets should be sharp to minimize losses. > The spacing between the buckets is made as big as possible, > but not larger than to secure that all water particles will hit a bucket. > > Theoretical velocity of jet: V = sqrt(2gh). (In practice a bit less) > Peripheral velocity of the runner: u (u can take any value from 0 to V) > Maximum power is obtained when u = V/2 (again in practice a bit less) > Theoretical optimum RPM = 60*sqrt(2gh)/(2*pi*D) so in theory D = > 42.3*sqrt(h)/RPM > A "practical" formula I found somewhere is: D = 38.6*sqrt(h)/RPM > considering losses. > Rotor diameter (D) and jet diameter (d) are not related in theory, > but there is a practical limit around D/d = 10, (a large jet will partially > miss a small rotor). > > (A simple solution to find suitable jet diameter for the pressure and flow > you are dealing with, could be to take a conical nozzle from a sealant tube > and experiment with a knife........) > > Best Regards. > > Thor. > -------------------------------------------------------------------- > Thorhallur Ragnarsson Electronics Technician/Instructor > Holtakoti Verkmenntaskolinn Akureyri > IS-641 HUSAVIK Eyrarlandsholti > Iceland IS-600 AKUREYRI > [EMAIL PROTECTED] Iceland > [EMAIL PROTECTED] [EMAIL PROTECTED] > http://www.simnet.is/holtakot http://thor.vma.is/not/thor > -------------------------------------------------------------------- > > > At 17:10 17.9.2005 +0000, kunoserg1703 wrote: > >Hi, it´s the Guatemalan student. I was wondering if any of you can > >help me finding the formulas on pelton design. > > > >I specifically need to know the bucket dimensions, and what is their > >relation with other pelton dimensions. I also need to know the > >relationship between rotor and nozzle dimensions. I have tried to find > >them over the internet, but I could only find the velocity relations, > >and power formula. If anyone can point me to a web page that contains > >the dimensions formulas, or email me them, I would appreciate it. > >Thanx. > > > >Sergio Linares > > > > > > > > > > > > > > > >Does your company feature in the microhydro business directory at > >http://microhydropower.net/directory ? If not, please register free of > >charge and be exposed to the microhydro community world wide! > > > >NOTE: The advertisements in this email are added by Yahoogroups who > >provides us with free email group services. The microhydro-group does not > >endorse products or support the advertisements in any way. > > > >More information on micro hydropower at http://microhydropower.net > > > >To unsubscribe: send empty message to [EMAIL PROTECTED] > >Yahoo! Groups Links > > > > > > > > > > > > > > > > Does your company feature in the microhydro business directory at > http://microhydropower.net/directory ? If not, please register free of charge > and be exposed to the microhydro community world wide! > > NOTE: The advertisements in this email are added by Yahoogroups who provides > us > with free email group services. The microhydro-group does not endorse > products > or support the advertisements in any way. > > More information on micro hydropower at http://microhydropower.net > > To unsubscribe: send empty message to [EMAIL PROTECTED] > Yahoo! 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