4.23. QSCHAR¶
4.23.1. QSCHAR (Class)¶
Fig. 4.23.1 Varying discharge boundary condition used to determine the system characteristic¶
Supplier type
type label |
description |
active |
|---|---|---|
QSCHAR |
varying discharge to determine the system characteristic |
yes |
4.23.1.1. Mathematical model¶
This hydraulic component is used to determine the system characteristic of (a part of) the hydraulic system. The system characteristic is a non-linear function H=f(Q) at a certain location.
For simple systems this curve can be derived easily while the coefficient C in H = C Q2 is constant. For branched systems where other head or flow dependant devices (like pumps) influence the head this coefficient C is not constant. The curve can be determined exactly by WANDA using a repeating calculation of steady.
Each calculation step the QSCHAR acts as a BOUNDQ component with a constant value. This value varies from 0 m3/s until Qmax m3/s in 25 equidistant steps
This H-component is especially used in the System characteristic module.
See help on the Model Menu “System characteristic chart” on page 109.
Running the modules Steady and Unsteady the QSCHAR exactly behaves like the BOUNDQ component.
For more information see “BOUNDQ (class)” (Section 4.5.3).
4.23.1.2. Hydraulic model aspects¶
Generally the QSCHAR represents a (set of) pumps. If you want to use this component in a model where the pump station is already modelled, it is not necessary to delete these pumps, check valves and H-nodes. Just toggle the “disuse” property of the pumps from “No” to “Yes”. Now the pumps are ignored in the calculation
Be careful using the QSCHAR component together with TAPS or other discharge prescribed components. Calculating the 25 Q-steps the values of the other discharge prescribed components are kept constant. These values are not scaled.
A model with only discharge prescribed components and no Head boundary condition at all will lead to a numerical error (singular matrix)
4.23.2. QSCHAR (BoundQ for system characteristic)¶
4.23.2.1. Hydraulic specifications¶
Description |
input |
unit |
range |
default |
remarks |
|---|---|---|---|---|---|
maximum discharge |
real |
m3/s |
|||
suction level |
real |
m |
|||
Marker Qmin |
real |
m3/s |
|||
Marker Qmax |
real |
m3/s |
See also “Mathematical model” (Section 4.23.1.1).
4.23.2.2. Component specific output¶
None
4.23.2.3. H-actions¶
In principal the QSCHAR is used for the system characteristic calculation. This is a repeating steady calculation. In transient mode the QSCHAR behaves like a BOUNDQ.
See “BOUNDQ (class)” on page 226.
4.23.2.4. Component messages¶
Pump head (m)