Hello ! Does anyone know how to increase the velocity/force of flowing water without using a pump ? I need to create sufficient force to turn a turbine ? I know without saying what kind of turbine it might be a bit hard to give the best solution I just need a general solution any available theory application --- Joseph Hartvigsen <[EMAIL PROTECTED]> wrote:
> Nandi, > I've recently built a turbine and helped a fellow > select a pump for > direct drive from the turbine. I haven't heard yet > how it worked. In > principle there are a couple of issues to consider. > First, a > centrifugal pump, unlike most generators, has a > specified direction of > rotation. With a Pelton, there is no issue as it is > symmetric and can > be flipped over to change the direction of rotation. > A turgo on the > other hand can also be turned over, but it changes > the jet entrance > and exit faces. In the case of the turbine I just > built for this > application this meant that the jet exit needed to > be on the pump > side. Normally I would prefer the other way so that > it is easier to > keep water off the pump bearings. A Pelton will > deflect water toward > the pump bearings no mater which direction of > rotation is required. > > The other factor is matching the torque vs. rpm > curves of the pump and > turbine. With a pump, the torque increases with rpm. > With a turbine, > the torque is highest at 0 rpm and decreases to 0 > torque at freewheel > rpm. Somewhere in the middle the two curves > intersect. That will be > the operating point. You need to match the turbine > to the pump so that > that point of intersection is also at the peak power > rpm of the > turbine. This rpm should also be a point compatible > with matching the > pump's output head and flow to that required by your > application. > > The torque/power vs. rpm for the turbine can be > computed with a > momentum balance. I have such a spreadsheet for any > impulse turbine on > my web site. Unfortunately, it is setup only for > units of hp, ft-lb, etc. > See http://h-hydro.com/turgo_drive.html near the > bottom of the page > > Most pumps are designed to be driven by an electric > motor at 3600 or > 1800 rpm (assuming 60Hz, or 3000/1500 rpm at 50 Hz). > You should be > able to obtain a pump curve from the manufacturer. > These pump curves > will likely be at 3600 or 1800 rpm. To scale to a > different rpm, what > is knows as "turbomachinery affinity laws" are used. > These laws help > scale a geometrically similar design to a larger or > smaller size, or > scale the performance of a fixed unique device as > head, flow, rpm, > power, etc. need to be changed. In the recent case I > helped with, he > was eventually able to find a 1200 rpm pump that > matched his needs, > but it was a custom industrial pump. > > This link has some info, but you can google > "turbomachinery affinity > laws" and find dozens of referrences. > http://caltechbook.library.caltech.edu/22/01/chap1.htm > For the same pump run under different conditions "D" > or the > characteristic diameter (usually the impeller or > runner diameter) is > fixed, and flow varies with rpm (double rpm doubles > flow capacity), > Head varies with rpm^2 (double rpm = 4x head) and > the same for torque. > Power varies as rpm^3. So if you have a pump rated > at 1800 rpm and run > it at 1400 rpm, its flow is reduced to 78%, head & > torque to 60% of > the 1800 rpm value, and power is reduced to 47% of > the rated power. > > > Joe > > > --- In [email protected], "S.N.Group of > Companies" > <[EMAIL PROTECTED]> wrote: > > > > hi all!!!! > > > > > > has any bodythought of using turbines to drive > centrifugal pumps > > directly?? > > we are currently working on a concept wherein the > turbine shft will be > > directly connected to the drive shaft of a > centrifugal pump . providing > > flow all year round . > > any help in this matter is solicited. > > > > regards, > > nandi > > > > > > > > __________________________________ Yahoo! Music Unlimited Access over 1 million songs. Try it free. http://music.yahoo.com/unlimited/ ------------------------ Yahoo! Groups Sponsor --------------------~--> Get fast access to your favorite Yahoo! Groups. Make Yahoo! your home page http://us.click.yahoo.com/dpRU5A/wUILAA/yQLSAA/FGYolB/TM --------------------------------------------------------------------~-> 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 <*> To visit your group on the web, go to: http://groups.yahoo.com/group/microhydro/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
