Modelica.Fluid.Valves.BaseClasses.ValveCharacteristics

Package Content

Name	Description
baseFun	Base class for valve characteristics
linear	Linear characteristic
one	Constant characteristic
quadratic	Quadratic characteristic
equalPercentage	Equal percentage characteristic

Modelica.Fluid.Valves.BaseClasses.ValveCharacteristics.baseFun

Information

Inputs

Type	Name	Default	Description
Real	pos		Opening position (per unit)

Outputs

Type	Name	Description
Real	rc	Relative flow coefficient (per unit)

Modelica definition

partial function baseFun "Base class for valve characteristics"
  extends Modelica.Icons.Function;
  input Real pos "Opening position (per unit)";
  output Real rc "Relative flow coefficient (per unit)";
end baseFun;

Modelica.Fluid.Valves.BaseClasses.ValveCharacteristics.linear

Information

Inputs

Type	Name	Default	Description
Real	pos		Opening position (per unit)

Outputs

Type	Name	Description
Real	rc	Relative flow coefficient (per unit)

Modelica definition

function linear "Linear characteristic"
  extends baseFun;
algorithm 
  rc := pos;
end linear;

Modelica.Fluid.Valves.BaseClasses.ValveCharacteristics.one

Information

Inputs

Type	Name	Default	Description
Real	pos		Opening position (per unit)

Outputs

Type	Name	Description
Real	rc	Relative flow coefficient (per unit)

Modelica definition

function one "Constant characteristic"
  extends baseFun;
algorithm 
  rc := 1;
end one;

Modelica.Fluid.Valves.BaseClasses.ValveCharacteristics.quadratic

Information

Inputs

Type	Name	Default	Description
Real	pos		Opening position (per unit)

Outputs

Type	Name	Description
Real	rc	Relative flow coefficient (per unit)

Modelica definition

function quadratic "Quadratic characteristic"
  extends baseFun;
algorithm 
  rc := pos*pos;
end quadratic;

Modelica.Fluid.Valves.BaseClasses.ValveCharacteristics.equalPercentage

Information

d(rc)/d(pos) = k d(pos).

The constant k is expressed in terms of the rangeability, i.e. the ratio between the maximum and the minimum useful flow coefficient:

rangeability = exp(k) = rc(1.0)/rc(0.0).

The theoretical characteristic has a non-zero opening when pos = 0; the implemented characteristic is modified so that the valve closes linearly when pos < delta.

Extends from baseFun (Base class for valve characteristics).

Inputs

Type	Name	Default	Description
Real	pos		Opening position (per unit)
Real	rangeability	20	Rangeability
Real	delta	0.01

Outputs

Type	Name	Description
Real	rc	Relative flow coefficient (per unit)

Modelica definition

function equalPercentage "Equal percentage characteristic"
  extends baseFun;
  input Real rangeability = 20 "Rangeability";
  input Real delta = 0.01;
algorithm 
  rc := if pos > delta then rangeability^(pos-1) else 
          pos/delta*rangeability^(delta-1);
end equalPercentage;