Restrictor, Contraction

Properties: adiabatic, not isentropic, directional, outlet based restrictor

Figure 98: Geometry of a contraction

The geometry of a contraction is shown in Figure 98. It is described by the following constants (to be specified in that order on the line beneath the *FLUID SECTION, TYPE=RESTRICTOR CONTRACTION card):

• full cross section $A_1$.
• reduced cross section $A_2$.
• hydraulic diameter $D_h$ of the reduced cross section defined by $D_h=4 A/P$ where $P$ is the perimeter of the cross section.
• chamfer length $L$.
• chamfer angle $\alpha$ ($^\circ$).
• 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 contraction is taken from [33].

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.

Example files: piperestrictor, restrictor, restrictor-oil.