On Monday, May 29, 2017 at 6:21:59 PM UTC-4, Jim Wilkins wrote:
wrote in message
...
On Monday, May 29, 2017 at 5:13:41 PM UTC-4, wrote:
On Monday, May 29, 2017 at 3:34:50 PM UTC-4,
wrote:
sw

Right. So what is the condition inside of one involute in the
second stage? Is it completely full when it's operating?

--
Ed Huntress


It is exactly the same as the first stage.

Dan

And what is that condition? Are the involutes completely filled?
And, if so, how is that possible unless the velocity is the same
from the input port to the periphery of the wheel?

--
Ed Huntress

How did you ever dream up that requirement?

Because if they are not completely filled, there is no physical way to transit any positive pressure at the inlet to the outlet. My further reading suggests they are filled, although some illustrations show them partly filled.. Photos taken through transparent windows show them partly filled, but those are illustrations of cavitation. I'm reaching the conclusion that they're completely filled in normal operation.

It isn't a positive
displacement pump. If the outlet valve is closed the input and output
velocities will be zero, yet the periphery is still spinning. The
pressure differential (p) from inlet to outlet will be what the
discharge curve shows for zero flow (q).
-jsw

If there is no flow, there will be no pressure differential. Pressure will be the same throughout the volume of liquid from inlet to outlet.

--
Ed Huntress