Mathematical Analysis of an Ideal ZED

[MarkE]

    I can imagine the scene in the Travis household. Sandy says "Wayne you're getting
   yourself into deep water with this stupid forum-you're  banned"!
        Which is pretty much the same as what goes on at my house, the women  keep
    things in order.
         I've been struggling with my sewage disposal machine. I have a fairly big family
    so it's a big 'un. 50 arse power. I put on a new motor three years ago and used a
    thermal overload that was too big so the motor ended up as toast. What amazed
     me was the unloaded current-it was very little less than what the trip had to be set
    for. Heaven knows how these mo-gen things are supposed to work
                     John.

AC induction motors look almost like dead shorts when they start up.  An electronic drive helps a lot.  This is a huge money saver for people with swimming pool and other kinds of water pumps that see frequent use.

[MarkE]

You need to cange B32 B33 B34 to use   =AR2+2*HorGAp  =AR4+2*HorGap =AR6+2*HorGAp and they all change and when I go back to 20 it gives me the same numbers as the first spreadsheet.

Why?,, Why not??

Why not?  Because the formulas for the OD's are all correct.  Each successive ring OD builds as the disk it surrounds plus twice the width of the respective ring.  The geometry is in the graphics.  HorGap sets the annular ring width, RiserWallThickness the riser walls, and RingWallThickNess the ring walls.

AR1 =PodOD+2*HorGap
RW1 =AR1OD+2*RingWallThickness
AR2 =AR1OD+2*(RingWallThickness+HorGap) //arithmetically the same as RW1 + 2*HorGap
R1 =AR2OD+2*RiserWallThickness
AR3 =Riser1OD+2*HorGap
RW2 =AR3OD+2*RingWallThickness
AR4 =AR3OD+2*(RingWallThickness+HorGap) //arithmetically the same as RW2 + 2*HorGap
R2 =AR4OD+2*RiserWallThickness
AR5 =Riser2OD+2*HorGap
RW3 =AR5OD+2*RingWallThickness
AR6 =AR5OD+2*(RingWallThickness+HorGap) //arithmetically the same as RW3 + 2*HorGap
R3 =AR6OD+2*RiserWallThickness
AR7 =Riser3OD+2*HorGap


If for example you change the HorGap from 1mm to 2mm then:
AR1 => 24mm
RingWall1 => 26mm
AR2 => 30mm
Riser1OD => 32mm
AR3 => 36mm
RingWall2 => 38mm
AR4 => 42mm
Riser2 => 44mm
AR5 => 48mm
RingWall3 => 50mm
AR6 => 54mm
Riser3 => 56mm
AR7 => 60mm

Just as they should.

[MarkE]

I am looking at the new and improved layout,, the split window does make it easier to see the changes and what they do,, very impressive.

My changes to your r3 did about the same thing for getting the diameters,, now there is even more information to look at with this new revision

The window split was not intentionally published.  That's just a left over from my own auditing process.  You can turn it on and off from the Window menu.  If you are working with something that you modified, then you are kind of on your own with respect to those modifications.  The latest version of the spreadsheet addresses comments that you made as to the readability of the formulas in the R3 version that preceded it, over and above fixing the way that I handled the riser walls.  The riser walls sit on a different head than the riser IDs and so the pressures and resulting forces are tracked for the riser walls separately from the IDs.  If you change the riser wall widths in R3 you can get calculated non-zero force in State 3, which of course means there is a problem.  In R4  you can make any of the widths a very small value, such as 1E-20mm and the force at the end of State 3 and State 1X both come out zero as they should.

[MarkE]

I was noticing some irregularities with revision 3,, which is why I was hoping you would post the correct fix, I did not think it would be as extensive as all that but it is more accurate now,,   and that is a good thing.

I did have an issue when I changed the VerGAp to 0  so I ended up leaving it at 1.  On revision3.

R3 did not handle the riser walls correctly.  There is also one cell formula that had a ring wall in it where a riser wall belonged.  As long as you don't do something that would break the assumptions, such as over or underflowing one of the annular rings, then R4 should yield valid results for any parameter change.

[MarkE]

With the split view I can see the heights and make sure that nothing "blows" a skirt

right now I am horsing around with it and have a B228 of 102.58 and a B227 of 52.2

Just by changing the numbers,, this is interesting to watch what changes change what.

Yes, it is pretty easy to burn up a lot a energy getting the machine set-up that you will never recover.  After that, so long as we ignore friction, it acts like a compression spring.