Pipe, Bend

Figure 116: Bend

A bend (Figure 116) is characterized by head losses $ \Delta_1^2 F$ of the form:

$\displaystyle \Delta_1^2 F = \zeta \frac{\dot{m}^2}{2 g \rho^2 A^2 },$ (157)

where $ \zeta$ is a head loss coefficient depending on the bend angle $ \alpha$ and the ratio of the bend radius to the pipe diameter $ R/D$, $ \dot{m}$ is the mass flow, g is the gravity acceleration and $ \rho$ is the liquid density. $ A$ is the cross section of the pipe. 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 BEND card:

$ \xi$ denotes the roughness of the pipe: $ \xi=0$ applies to an extremely smooth pipe surface, $ \xi=1$ to a very rough surface. 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.