Another Flow rate calculation?
Another Flow rate calculation?
(OP)
The flow rate setting on my DCV is 30 GPM. The DCV controls a 4 stage telescoping cylinder. I'm trying to determine the discharge flow coming from the rod end when the cylinder is extending. i thought it was a simple velocity/cross sectional area. but i'm getting a discharge value that doesn't seem right to me. could someone please advise the correct formula?
here's what i did: v1=Q/A1(1st stage), Q2 = v1*A2(2nd stage), v2=Q2/A2(2nd Stage), Q3=v2*A3(3rd stage), v3=Q3/A3 (3rd stage), Q4=v3*A4 (Discharge Flow Rate).
by the time I get through all the area reduction ratios i barely have any flow coming out of the rod end.
here's what i did: v1=Q/A1(1st stage), Q2 = v1*A2(2nd stage), v2=Q2/A2(2nd Stage), Q3=v2*A3(3rd stage), v3=Q3/A3 (3rd stage), Q4=v3*A4 (Discharge Flow Rate).
by the time I get through all the area reduction ratios i barely have any flow coming out of the rod end.





RE: Another Flow rate calculation?
flow entering the large end = flow exiting the small end + collection due to expansion of the arm.
RE: Another Flow rate calculation?
Cylinder n flowrate is,
Qn = Q1/A1 x An
Cylinder n Velocity is,
V = Q1/A1 and a constant
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RE: Another Flow rate calculation?
However, if I understand the situation, there is a telescoping cylinder involved. This cylinder has inlet and outlet ports at the large, "fixed" end and smaller "travelling" end, respectively. As the fluid is pumped into the large end, the fluid pressure acts on the telescoping arm, extending it, then ultimately flowing out of the small end. In this case, a term for the fluid that stays in the arm must be included in the analysis of any of the sections, as their volume is constantly changing as the system is running.
For instance, let's say you're pumping 1 cu. ft/sec of fluid through a cylinder. It is able to telescope, but it is all locked down, so it can't move. You pump the fluid through the cylinder in this case, and 1 cu ft goes in and 1 cu ft comes out per second. Now, the same system is running, and you release the locks. It just so happens that due to the telescoping action of the arm, the volume of the internal space increases by 1 cu. ft./second. Then, at the moment you release the locks on this system, fluid ceases to flow out of the outlet port, as all of the fluid being pumped in collects in the arm and is used to expand the arm instead of just flowing through it. This is what I meant by adding a "collection" term to the equation. This increasing capacity of the arm must be accounted for in a fluid balance.
RE: Another Flow rate calculation?
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