Nominal mass flow rate, nominal pressure drop, nominal density in a valve in modelica

Question

I have a question about nominal values (nominal density, nominal massflowrate, nominal pressure drop) which are required in valves in modelica. I couldnt find any formula or explanation on how to calculate these values. Do you know how to calculate them? Thanks

Answer 1

If you open the model for the ValveLinear, you find the following equation:

m_flow = opening*k*dp;

k is defined the following way:

k = m_flow_nominal/dp_nominal

So you can use these formulas to calculate the parameters. You can find data about your valve in the datasheet for it or you can look for typical values for valves of that size. The relation of pressure drop to massflow looks somehow like this:

found the picture here: https://www.hawe.com/fluid-lexicon/pressure-drop-flow-rate-chart-for-valves/