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Minimizing pulsatility in a stretch tube - help needed!

Minimizing pulsatility in a stretch tube - help needed!

Minimizing pulsatility in a stretch tube - help needed!

(OP)
I'm a fluids novice, but am working on a fluid mechanics problem, so I'm stuck quickly learning, and thought I'd seek out advice from the forum.

Anyhow, I'm working with a flexible, stretchy tube with pulsatile fluid flow.  During a pressure spike, the walls of the tube, expand, allowing accomodation of increased volume, and then slowly perfuses this extra volume into the stretchy tube.  The stretchy tube dampens the pressure spike during pulsation (which is an improvement over a rigid pipe), but I'm stuck trying to further minimize pulsation (reduce the pressure spike - likely through pressure redistribution to regions in the pipe of lower pressure - preferably upstreatm, so as to maintain a pressure drop in the stretchy tube and maintain flow).

Any thoughts on how to achieve this goal?  I'm contempating wrapping a water filled tube (think water snake - child's toy) around the stretchy tube, and applying a constant pressure to the outside of this water filled tube, and potentially providing a rigid exterior.  As such, a pressure spike would force movement of the water in the water filled tube to regions of lower pressure that are in contact with the water filled tube...this should redistribute pressure either forward or backward in the stretchy tube.

Is this a ridiculous idea?  Do you think it would help buffer the pressure spikes?  Would there be benefits beyond increased frictional losses (due to water movement)?  

I realize that this is an odd petro-eng problem.  Cheers and thanks!

Any comments would be greatly appreciated.   

RE: Minimizing pulsatility in a stretch tube - help needed!

a bellow may be at the the beginning of the flex tube?

RE: Minimizing pulsatility in a stretch tube - help needed!

You are reinventing the wheel. There are commercial "pulsation dampeners" readily available. Most involve an air-filled chamber. Try Google.

RE: Minimizing pulsatility in a stretch tube - help needed!

wrapping it with water won't work, because if you increase the pressure on the water wrap at one point, water sees to it that the pressure increase is equally distributed everywhere.

Make the whole length of pipe flexible and support it well.

From "BigInch's Extremely simple theory of everything."

RE: Minimizing pulsatility in a stretch tube - help needed!

(OP)
Thanks for the help.  I have seen the gas filled chamber dampeners, but I'm trying to avoid adding such a chamber.  Ideally the dampening mechanism would function by applying forces external to the stretchy tube, without puncturing/cutting it, or else by modifying the internal geometry of the stretchy tube (i.e. something that can be placed inside the tube that doesn't span to the outside of the tube.

I have thought about captive acceleration tubes, but I don't know if I can increase localized elasticity, if I either place this inside or outside the tube.

As for the water tube around the stretchy tube idea - what would happen if I simply applied it to a small portion of the stretchy tube (i.e. 4 inches of a 4 foot stretchy tube - of which there is a vacuum applied to the end of the 4 foot tube to ensure pressure drop between the inlet and outlet)?...this likely speaks towards my fluids naivity.

I sincerely appreciate all of your thoughts - it would be nice not to have to "reinvent the wheel"...

RE: Minimizing pulsatility in a stretch tube - help needed!

(OP)
I didn't mention this, in context of me resurfacing the water tube idea - the length of the water tube would be approximately equivalent to the wavelength of the pulse (i.e. in the example above, the wavelength of the pulse would be 4 inches).

Again - I sincerely appreciate the help/thoughts...

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