Restrictor, Wall Orifice

Properties: adiabatic, not isentropic, directional, $A$-outlet based restrictor

Figure 97: Geometry of a wall orifice

The geometry of an wall orifice is shown in Figure 97. It is described by the following constants (to be specified in that order on the line beneath the *FLUID SECTION, TYPE=RESTRICTOR WALL ORIFICE card):

• not used (internally: set to 100,000 $A$ as upstream section)
• reduced cross section $A$.
• hydraulic diameter $D_h$ defined by $D_h=4 A/P$ where $P$ is the perimeter of the cross section.
• length L
• oil mass flow in the restrictor (only if the OIL parameter is used to define the kind of oil in the *FLUID SECTION card)
• not used (internally: oil material number)

The loss coefficient for a wall orifice is taken from [34].

By specifying the parameter LIQUID on the *FLUID SECTION card the loss is calculated for liquids. In the absence of this parameter, compressible losses are calculated.