Modelica.Fluid.Valves.BaseClasses.ValveCharacteristics

Functions for valve characteristics

Information

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

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

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

Name Description

pos Opening position (0: closed, 1: fully open)

Name	Description
pos	Opening position (0: closed, 1: fully open)

Outputs

Name Description

rc Relative flow coefficient (per unit)

Name	Description
rc	Relative flow coefficient (per unit)

Modelica.Fluid.Valves.BaseClasses.ValveCharacteristics.linear

Linear characteristic

Information

Extends from baseFun (Base class for valve characteristics).

Inputs

Name Description

pos Opening position (0: closed, 1: fully open)

Name	Description
pos	Opening position (0: closed, 1: fully open)

Outputs

Name Description

rc Relative flow coefficient (per unit)

Name	Description
rc	Relative flow coefficient (per unit)

Modelica.Fluid.Valves.BaseClasses.ValveCharacteristics.one

Constant characteristic

Information

Extends from baseFun (Base class for valve characteristics).

Inputs

Name Description

pos Opening position (0: closed, 1: fully open)

Name	Description
pos	Opening position (0: closed, 1: fully open)

Outputs

Name Description

rc Relative flow coefficient (per unit)

Name	Description
rc	Relative flow coefficient (per unit)

Modelica.Fluid.Valves.BaseClasses.ValveCharacteristics.quadratic

Quadratic characteristic

Information

Extends from baseFun (Base class for valve characteristics).

Inputs

Name Description

pos Opening position (0: closed, 1: fully open)

Name	Description
pos	Opening position (0: closed, 1: fully open)

Outputs

Name Description

rc Relative flow coefficient (per unit)

Name	Description
rc	Relative flow coefficient (per unit)

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

Name Description

pos Opening position (0: closed, 1: fully open)

rangeability Rangeability

delta

Name	Description
pos	Opening position (0: closed, 1: fully open)
rangeability	Rangeability
delta

Outputs

Name Description

rc Relative flow coefficient (per unit)

Name	Description
rc	Relative flow coefficient (per unit)

Automatically generated Mon Sep 23 17:20:48 2013.