Restrictor, Entrance

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

An entrance element is used to model the entry from a large chamber into a gas pipe. For an entrance the value of $\zeta$ is 0.5. It is described by the following constants (to be specified in that order on the line beneath the *FLUID SECTION, TYPE=RESTRICTOR ENTRANCE card):

• not used (internally: set to 100,000 $A$ as upstream section)
• cross section of the entrance $A$.
• hydraulic diameter $D_h$ defined by $D_h=4 A/P$ where $P$ is the perimeter of the cross section.
• not used (internally: set of 0.5 as pressure loss coefficient)
• 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)

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.