Hydraulic Piston Velocity through a Known Fluid

[bduff]

Any Help you could provide with the following question would be greatly appreciated.

Problem: I am trying to determine the velocity of a piston through a hydraulic cylinder. (Rod goes through the piston with a gap of known area to allow allow the fluid to flow from one side of the cylinder to the other) The piston has a spring behind it as its only force to propel through the fluid. I would like to know how to analyze the relationship between the gap area (gap between rod and piston) and the force behind the piston. This will help me size my gap and spring accordingly.

Thanks

 

[BigInch]

Not easy to do without making some assumptions to simplify.
Flow will be through an orifice with a pressure differetial.
Relate the pressure on the cylinder to the position of the spring.
Take a small time increment and calculate postion of the cylinder at each time step.
When the spring is compressed, the velocity of fluid through the orifice will be fast and go slower and slower as the spring expands and lessens the pressure in the cylinder. Use a small enough timestep so that the average velocity can be used from the beginning to the end of the timestep. Use that fluid velocity to calculate piston movement during the time increment. Do again...

Independent events are seldomly independent.

 

[bduff]

Thanks. Sounds like a reasonable approach. I'll do the calcs and then do some actual testing once the prototype is complete.

Thanks again!