Quote from: Red_Sunset on September 23, 2012, 01:02:35 PM
I assume, You put the weight on, then you stroke 10 mm. As I see it, as you put the 1.2kg weight on, you get the 238 head (the risers & pod are floating with that weight on top)
By adding water to stroke the way you do, you basically raise the water level in the pod and the pod & risers will basically keep floating higher as the water level rises.  No head increase takes place at that point. The pressure doesn't change.  So technically the water in the pipe is expected to rise only ~10mm, in your case it is more than 4x more (46mm).

Michel, I ran the lift test again as meticulously as I could.  This time the heads were:

Pre lift:  241 mm
Post 10 mm lift: 281 mm

So, still well more than the 10 mm difference I would also predict at first.  But those are the results.  Sorry for not being able to share pictures of this test.  I took much more time to let the system completely settle for these data points compared to the previous ones.

M.

@RS

QuoteWhat do you mean with
POD level is 4.5"
Difference then is 19"

My meaning of the statement was, to use the inside bottom of the Zed as the zero reference for vertical measurements in the tube.

All of the distance measurements are taken from that reference point: The top of the base plate ( bottom inside of the ZED)
The base plate is 1/2" and is larger than than the Tank wall so any measurements taken on the ZED levels have a ruler resting on the plate.

The sight gauge rule is also resting on a scrap piece of the same material.

Both rulers are trimmed to 0"

The level of water inside the POD chamber is 4.5" from the base (POD is 1" up) - External input head is 23.5"

Dale

Quote from: Red_Sunset on September 23, 2012, 09:26:04 AM
You will observe yourself that the outer layer lift area is only the horizontal rim between the risers where the u-bend and retainer are located. That area is not very big.
The central circular area of the pod is usually the biggest area if no specific changes have been done to change that ratio during the design stage.
Keep in mind also that the outer area is the top of the water column with the lowest pressure delta.

So, if you do not make special design changes at the start to distribute the area space between the layers, that is what you get. From my survey calculations, the total lift force will always be less than the stacked risers.

Michel

Hi Michel,

I have a slight difference of opinion about the single top lift compared to separate risers. I believe they are the same.


The first picture shows that an Archimedes calculation and the Pressure Differential calculations produce the same results for certain uniform shapes. This is basic just to get everybody on the same page for the next picture.


The second picture show the PSI forces on a single top Zed. Note how the bottom of the riser wall is also a downward facing surface being lifted. This small model is similar to Dale's where the walls and gaps are 1/8 inch. So the first outer riser has a 1 psi upward force on the outer riser bottom surface(1/8) and on the top inner surface U (3/8) above the retainer wall. If you have a separate riser version there would now be a 1 PSI downward force on the riser below. So these 2 opposite forces would cancel out everything but the outer surface larger difference. Same as you go inward.


Note for replicators: I added only two side PSI arrows at midpoint of out riser wall. This shows the inside of the riser wall has 1 PSI and the outside .5. Not a problem for a solid wall, but this can cause distortions on a wall that is to flexible. The difference is greatest at the top and least at the bottom.


This example also brings out the fact that the inner downward facing surface are feeling ever increasing depth pressure while the top surface remains at 0. While a hydraulic would only feel 5 PSI with a much smaller SI equal to the pod retainer wall inner diameter SI.
 

Regards, Larry

Quote from: poynt99 on September 23, 2012, 10:04:52 AM
mondrasek,

Your video link seems to be broken.
http://youtu.be/YwXsoqm75WY

Something's wrong with the link in your post. Try this:
http://www.youtube.com/watch?v=YwXsoqm75WY

Both links work for me.  I'm using Internet Explorer 8.0.