Not, the ones I worked with (5 foot diameter, turning maybe a little faster than 1 revolution per second), but there is significant leakage between the screw and the tube. The working clearances for machinery that big, and without getting into costly tight tolerances are loose, maybe 1/2" or more between the screw and tube. On 7/9/2010 7:55 AM, Sean Breheny wrote: > Isn't the screw, when stopped, a continuous inclined plane so that > water poured in at one end would just run "downhill" around the turns > of the screw and out the other end? I did look at the photos and > that's what it appeared to me. > > Sean > > > On Fri, Jul 9, 2010 at 4:30 AM, wrote: > >>> I'm not sure if that's a joke or not. I realize that the water which >>> has fully reached the top will not backflow since it is lower than the >>> end of the screw. However, any water inside the screw will flow back >>> down into the lower pool if the screw speed is insufficient to keep up >>> with the pull of gravity on the water. Am I missing something? >>> >>> On Thu, Jul 8, 2010 at 9:03 PM, John Gardner wrote: >>> >>>> What backflow? :) >>>> >> It's not a joke, as for most of the screw the water does not cover the screw, so the water cannot backflow. If the screw is made as a channel with an open top (see the pictures in the links I posted previously about power generation using a screw) then the only backflow is when the water overflows a turn of the screw. >> >> There will be a trickle backflow due to an inevitable gap between the screw and the channel, but careful design would make this reasonably minimal. >> -- >> Scanned by iCritical. >> >> -- >> http://www.piclist.com PIC/SX FAQ& list archive >> View/change your membership options at >> http://mailman.mit.edu/mailman/listinfo/piclist >> >> > -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist