equalPercentage

Equal percentage characteristic

Information

This information is part of the Modelica Standard Library maintained by the Modelica Association.

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.

Syntax

rc = equalPercentage(pos, rangeability, delta)

Inputs (3)

pos

Type: Real

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

rangeability

Default Value: 20

Type: Real

Description: Rangeability

delta

Default Value: 0.01

Type: Real

Outputs (1)

rc

Type: Real

Description: Relative flow coefficient (per unit)