Pipe, Diaphragm

Figure 115: Diaphragm

A diaphragm (Figure 115) is characterized by head losses $\Delta_1^2 F$ of the form:

$$\Delta_1^2 F = \zeta \frac{\dot{m}^2}{2 g \rho^2 A^2 },$$ (169)

where $\zeta$ is a head loss coefficient depending on the ratio $A_0/A$, $\dot{m}$ is the mass flow, g is the gravity acceleration and $\rho$ is the liquid density. $A_0$ and $A$ are the cross section of the diaphragm and of the pipe, respectively. Values for $\zeta$ can be found in file “liquidpipe.f”.

The following constants have to be specified on the line beneath the *FLUID SECTION, TYPE=PIPE DIAPHRAGM card (internal element label: DLIPIDI):

• $A > 0$
• $A_0 \;\;\;(\le A, > 0)$

The gravity acceleration must be specified by a gravity type *DLOAD card defined for the elements at stake. The material characteristic $\rho$ can be defined by a *DENSITY card.