functionequalPercentage
Equal percentage characteristic
Extends from baseFun (Base class for valve characteristics).
Information
This characteristic is such that the relative change of the flow coefficient is proportional to the change in the stem 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.
Inputs
| Type | Name | Default | Description |
|---|---|---|---|
| Real | pos (from baseFun) | Stem position (per unit) | |
| Real | rangeability | 20 | Rangeability |
| Real | delta | 0.01 | Characteristic is linear for opening < delta |
Outputs
| Type | Name | Default | Description |
|---|---|---|---|
| Real | rc (from baseFun) | Relative coefficient (per unit) |