Pressure distribution in rotating pipe. (dynamics and fluid mechanics)

AI Thread Summary
The discussion focuses on calculating the pressure at the end of a centrifuge arm with a radius of 3 meters and a G level of 100g. The user initially attempted to apply the static pressure head formula but struggled due to the non-linear nature of acceleration in this context. After several calculations, they arrived at a pressure value of 263,908, which they suspected might be in kilopascals. Upon further reflection, they revised their approach, concluding that the correct pressure should be calculated as 2589 kPa or 375.5 PSI. The user seeks confirmation on the accuracy of their final calculations and assumptions.
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I have a centrifuge with hydraulic lines on the arm. I need to calculate the pressure that will be developed at the end of the centrifuge arm in the hydraulic lines.

The radius of the arm is 3 meters. At the end of the arm the G level will be 100g. Obvioulsy the g level at the center point is 0g in the radial direction. I tried to tie together the static pressure head formula, as well as some of my dynamics formulas but the resulats do not make sense. I have made an incorrect assumption somewhere along the line.

For regular old pressure, you have P2=pgh

where:
p="rho" the desity of the fluid
g= acceleration due to gravity, (9.81) A CONSTANT
h= depth of the fluid in meters.


Now my acceleration due to gravity is NOT constant, and is NOT linear. I tried simply substituting my g formula into the above aquation, noting that"

An=(w^2)(r)

a formula that would result in units of M/s/s. I then normalized this to "g's" by dividing by 9.81 to have:

g=((w^2)(r))/9.81

Substiuting both together, and nothing that in my opinion r=h you get:

P2= p [((w^2)(r))/9.81] (r)

which simplifies to: P2=p[((w^2)(r^2))/9.81]

now the density of hydraulic oil is 880 Kg/m^3

Omega is 18.08 Rad/sec

and R=3.

you get 263,908 somethings. I am not quite sure what the units are, but I am thinking kilopascals?

Is this correct? Are my assumptions correct or are they wildly off base? Either way I have thought about this for quite some time and I am very unsure.

please help.

Thank you.
 
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I thought about this a bit further, and the original pgh formula uses m/sec^2 as the units of g, so dividing this by 9.81 to go back to a unit of "g's" seems like a mistake now.

I think pressure = p(w^2)(r^2) should be correct but I would still appreciate input on this!

so it comes down to pressure = (880)(18.08^2)(3^2)= 2589KPA

=375.5 PSI.

Thoughts?
 
Can anyone help me out on this? I really need a definitive answer.
 
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