Flow Rate Calculation for Air Pressure in Cylinder

[rivo]

Homework Statement

Greetings!
I am a student from Estonia and I have a little problem with my assignment. I have to make a simulator that controls air pressure in a cylinder.
I need to calculate how much pressure flows into a cylinder each second. To do that I need to know the the flow rate depending on the size
of the input opening. By knowing the pressure in the cylinder I can see if I need to open the inlet a little or close it. My assignment is theoretical
so any data needed can be chosen randomly. But if size does matter then the inlet pipe max diameter should be smaller than 10 mm. I've tried to look
for a formula but have not found a good one.

The Attempt at a Solution

I've tried a calculator and formulas from here http://www.pipeflowcalculations.com/pipeflowtheory/pressure-drop-equation-in-isothermal-flow.php bur my answers do not add up.
Are there any better ways to calculate air flow.If someone can help me with my problem, I would be very grateful.

Best wishes,
Rivo

 

[_coyote_]

The formula for calculating the pressure drop in isothermal flow of an incompressible fluid (such as air) can be expressed as:P_1 - P_2 = (ρ/2)*(V_1^2 - V_2^2) where P_1 and P_2 are the pressures at points 1 and 2, respectively; ρ is the density of the fluid; and V_1 and V_2 are the velocities of the fluid at points 1 and 2, respectively. This formula can be used to calculate the pressure drop across a given section of pipe or tubing of known length, diameter, and fluid velocity.