tc7
Mechanical
- Mar 17, 2003
- 387
Is it possible to calculate the natural frequency of a free floating piston in a piston accumulator?
Background: I have a long piston accumulator (~14 ft long)
with a 14" diameter piston, air on one side, ethylene glycol on the other. Its purpose is to receive the fluid which is exhausted from a throttling process which I won't describe now. In monitoring the accumulator pressure on the liquid side during the process (starts at ~400 psi and ends at ~600 psi) I am observing high frequency oscillation
which is not normal. These oscillations are evident in other parts of the process system as well. I am guessing that one possibility for the source of the unknown oscillations may be that the free floating piston is chattering during its stroke, possibly due to excess cylinder wear, and the cylinder is possibly worn into a slightly oval shape. I cannot at this time open and inspect. I can make educated assumptions concerning clearances between cylinder I.D. and piston O.D. without disassembly. I can also make educated assumptions on piston velocity.
What method might I use for calculating theoretical frequency if I know piston velocity and clearances? Is it possible?
Thankyou for any ideas.
Tom
Background: I have a long piston accumulator (~14 ft long)
with a 14" diameter piston, air on one side, ethylene glycol on the other. Its purpose is to receive the fluid which is exhausted from a throttling process which I won't describe now. In monitoring the accumulator pressure on the liquid side during the process (starts at ~400 psi and ends at ~600 psi) I am observing high frequency oscillation
which is not normal. These oscillations are evident in other parts of the process system as well. I am guessing that one possibility for the source of the unknown oscillations may be that the free floating piston is chattering during its stroke, possibly due to excess cylinder wear, and the cylinder is possibly worn into a slightly oval shape. I cannot at this time open and inspect. I can make educated assumptions concerning clearances between cylinder I.D. and piston O.D. without disassembly. I can also make educated assumptions on piston velocity.
What method might I use for calculating theoretical frequency if I know piston velocity and clearances? Is it possible?
Thankyou for any ideas.
Tom
