What I meant is that the flow axis (also the turbine propeller axis) should be vertical to insure that the flow tube (housing the turbine) is fully filled.
I believe such turbines have a rotor (like a propeller) with an axis coaxial with the flow tube and low blockage spider supports for the rotor shaft. Then there is an electrical or mechanical coupling of the rotor rotation to measure the flow speed usually out the side of the flow tube. If the flow tube were mounted horizontally and the pipe was half full, to first order it would indicate twice the flow as actual. Second order effects have to take into account the turning resistance of the turbine, which is usually very low. Again, the turbine is measuring the speed of the flowing medium whether it is full or not (to first order). On Mon, Aug 8, 2016 at 8:40 AM, Jed Rothwell <[email protected]> wrote: > Bob Higgins <[email protected]> wrote: > > >> Do you know the orientation of the flow meter? It is only possible to >> have a pipe half full if the flow meter is mounted horizontally (a mistake >> for use of this type of flow meter). >> > > Umm . . . I don't follow what you mean. Do you mean the pipe should be > vertical? I don't know what you mean by having the flow meter vertical. > Like, sideways? It is a rotor smack in the middle of the pipe . . . so I > don't get what you mean. > > The pipe was horizontal and the flow meter face plate is up. As far as I > know. > > > >> If the flow meter was mounted horizontally, and the pipe was half full, >> the turbine would turn at the speed of the water (same as if it were full) >> - since a full pipe was presumed in the indication of rate, it would be in >> error by the volumetric difference between the pipe full volume and the >> pipe partly filled volume. >> > > I believe the error can be complicated. It is not like: "the pipe is half > full so the actual flow rate is half of what is indicated." A partially > full pipe can produce a huge error. That is my impression reading about > flow meters and using them myself, but I have no specific information on > the extent of the error in Rossi's setup. (I think I.H. does have this > information.) As you saw, I estimated it has to be at least 3. That seems > plausible to me. > > - Jed > >
