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Pipe, Sudden Contraction

Figure 91: Sudden Contraction
\begin{figure}\epsfig{file=Contraction.eps,width=8cm}\end{figure}

A sudden contraction (Figure 91) is characterized by head losses $ \Delta_1^2 F$ of the form:

$\displaystyle \Delta_1^2 F = \zeta \frac{\dot{m}^2}{2 g \rho^2 A_2^2 },$ (31)

where $ \zeta$ is a head loss coefficient depending on the ratio $ A_2/A_1$, $ \dot{m}$ is the mass flow, g is the gravity acceleration and $ \rho$ is the liquid density. $ A_1$ and $ A_2$ are the larger and smaller cross section, respectively. Notice that this formula is only valid for $ \dot{m} \ge 0$. For a reverse mass flow, the formulas for a pipe enlargement have to be taken. 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 CONTRACTION card:

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.


Example files: centheat1, pipe.


next up previous contents
Next: Pipe, Entrance Up: Fluid Section Types: Liquids Previous: Pipe, Sudden Enlargement   Contents
guido dhondt 2012-10-06