Modelica.Fluid.Valves.BaseClasses.ValveCharacteristics

Functions for valve characteristics

Information

Extends from Modelica.Icons.VariantsPackage (Icon for package containing variants).

Package Content

Name Description
Modelica.Fluid.Valves.BaseClasses.ValveCharacteristics.baseFun baseFun Base class for valve characteristics
Modelica.Fluid.Valves.BaseClasses.ValveCharacteristics.linear linear Linear characteristic
Modelica.Fluid.Valves.BaseClasses.ValveCharacteristics.one one Constant characteristic
Modelica.Fluid.Valves.BaseClasses.ValveCharacteristics.quadratic quadratic Quadratic characteristic
Modelica.Fluid.Valves.BaseClasses.ValveCharacteristics.equalPercentage equalPercentage Equal percentage characteristic

Modelica.Fluid.Valves.BaseClasses.ValveCharacteristics.baseFun Modelica.Fluid.Valves.BaseClasses.ValveCharacteristics.baseFun

Base class for valve characteristics

Information

This is a partial function that defines the interface of valve characteristics. The function returns "rc = valveCharacteristic" as function of the opening "pos" (in the range 0..1):

    dp = (zeta_TOT/2) * rho * velocity^2
m_flow =    sqrt(2/zeta_TOT) * Av * sqrt(rho * dp)
m_flow = valveCharacteristic * Av * sqrt(rho * dp)
m_flow =                  rc * Av * sqrt(rho * dp)

Extends from Modelica.Icons.Function (Icon for functions).

Inputs

NameDescription
posOpening position (0: closed, 1: fully open)

Outputs

NameDescription
rcRelative flow coefficient (per unit)

Modelica.Fluid.Valves.BaseClasses.ValveCharacteristics.linear Modelica.Fluid.Valves.BaseClasses.ValveCharacteristics.linear

Linear characteristic

Information

Extends from baseFun (Base class for valve characteristics).

Inputs

NameDescription
posOpening position (0: closed, 1: fully open)

Outputs

NameDescription
rcRelative flow coefficient (per unit)

Modelica.Fluid.Valves.BaseClasses.ValveCharacteristics.one Modelica.Fluid.Valves.BaseClasses.ValveCharacteristics.one

Constant characteristic

Information

Extends from baseFun (Base class for valve characteristics).

Inputs

NameDescription
posOpening position (0: closed, 1: fully open)

Outputs

NameDescription
rcRelative flow coefficient (per unit)

Modelica.Fluid.Valves.BaseClasses.ValveCharacteristics.quadratic Modelica.Fluid.Valves.BaseClasses.ValveCharacteristics.quadratic

Quadratic characteristic

Information

Extends from baseFun (Base class for valve characteristics).

Inputs

NameDescription
posOpening position (0: closed, 1: fully open)

Outputs

NameDescription
rcRelative flow coefficient (per unit)

Modelica.Fluid.Valves.BaseClasses.ValveCharacteristics.equalPercentage Modelica.Fluid.Valves.BaseClasses.ValveCharacteristics.equalPercentage

Equal percentage characteristic

Information

This characteristic is such that the relative change of the flow coefficient is proportional to the change in the opening position:

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

NameDescription
posOpening position (0: closed, 1: fully open)
rangeabilityRangeability
delta 

Outputs

NameDescription
rcRelative flow coefficient (per unit)
Automatically generated Thu Dec 19 17:20:10 2019.