Orifice ISO 6358 - MapleSim Help

Orifice ISO 6358

Fixed pneumatic orifice

Description

This Orifice component adheres to ISO standard 6358. The component calculates the mass flow rate through the orifice based on the upstream and downstream pressures, respectively. When the pressure ratio is almost unity, the compressibility effects are almost not valid and the component is assumed to have a linear relationship with the pressure drop.

 Formulation Approaches Two approaches were taken for the formulation of the flow equation inside the component. When the boolean parameter  is true, the flow area at the local restriction can be provided which will be converted to sonic conductance using Gidlund's approximation.
 Equations $p={p}_{A}-{p}_{B}$  Orifice Gas Equation Linear Gain k is given by   When  is checked, Gidlund's approximation is used to calculate the sonic conductance using the restriction area

Variables

 Name Units Description Modelica ID $p$ $\mathrm{Pa}$ Pressure drop from A to B p ${p}_{X}$ $\mathrm{Pa}$ Pressure at port X pX $\mathrm{mflow}$ $\frac{{m}^{3}}{s}$ Mass flow rate from A to B mflow ${\mathrm{mflow}}_{X}$ $\frac{{m}^{3}}{s}$ Mass Flow into port X mflowX ${\mathrm{hflow}}_{X}$ $\frac{J}{\mathrm{kg}}$ Specific Enthalpy into port X hflowX

Connections

 Name Description Modelica ID $\mathrm{portA}$ Upstream Pneumatic port portA $\mathrm{portB}$ Downstream Pneumatic port portB

Parameters

Fluid Medium Parameters

The Gas parameters used in the equations, are properties defined in the Gas Model component used in the model.

 Name Default Units Description Modelica ID $\mathrm{true}$  When true the default gas properties defined for Air will be used. useDefaultMedium $\mathrm{medium}$ $-$  when Use default medium is false this option gets turned on. The user can specify the name of the Gas model dragged into the canvas. medium

Orifice Parametrization

 Name Default Units Description Modelica ID $\mathrm{C__Sonic}$ $1·{10}^{-7}$ $\frac{{m}^{3}}{s\cdot \mathrm{Pa}}$ Sonic conductance Csonic $\mathrm{false}$ True (checked) means flow restriction area can be given which will be converted to sonic conductance based on Gidlund's approximation UseRestrictionArea $b$ $0.54$ Critical pressure ratio bcr $\mathrm{b__lamreg}$ $0.999$ Flow transition constant from turbulent to laminar zone blamreg $\mathrm{Ar}$ $0.0001$ ${m}^{2}$ Flow area of the local restriction; used when $\mathrm{UseRestrictionArea}$ is false Ar