Fluid Behavior orifice or piston-like design

[atm98]

Hello all.

I am working on a very large hydraulic shock absorber (spring is pressurized nitrogen). The dampening is done by an orifice. My concern is that the orifice is restricting flow and negating the spring's behavior. Is there any difference in the orifice design as compared to a piston design (multiple orifices)? What if I increased the length of the orifices so there is more surface area?

Seems like the goal is to create friction but not restrict flow. Is this the correct assumption?

Any thoughts or ideas will be helpful.

 

[BigInch]

What's flowing?

Do you have a liquid entering a N2 chamber through an orifice? Why do you want to slow down entry by using an orifice?

Anyway, if the orifice is restricting flow significantly, you will have a "spring" effect. Its just not as fast as you were thinking it was going to be. Make the orifice a larger diameter and N2 pressure will build faster, since liquid is entering faster. When the N2 reaches the pressure of the liquid entering, the pressures will balance and the liquid will stop. When the liquid pressure outside the chamber reduces below that of the N2 chamber, liquid will flow back out from the chamber into the exterior piping. The "spring" is the flowrate through the orifice caused by the differential pressures across it.

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"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[BigInch]

You can also see this thread of a couple of days ago,
thread164-235617

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[Zapster]

What are you trying to do? Can you provide a damping profile for what you are trying to do? Do you want to have some constant amount of friction in addition to some variable friction force based on position and rate of change for the position? Try to derive an equation stating exactly what you want/need for damping before you decide how to accomplish the task.