Two Orifices $—$ Two orifices in series, one with variable the other with fixed flow area

The Two Orifices component describes two orifices that are connected in series without a lumped volume between them. This component can help to avoid a stiff system if the lumped volume between the two orifices is very small and its time constant negligible compared with the system dynamics. The mathematical models are taken from Metering Ori and Orifice. The diameter of the variable orifice is given by the value at the signal connector as $\mathrm{commandedDiameter}$ $\left[m\right]$ and the diameter of the fixed orifice is set with the $d$ parameter (found under the Inspector tab in the Parameters section). The mass and flow forces are not included.

Related Components

 Name Description Resistance with laminar flow. Resistance with laminar flow and externally commanded conductance. The component, based on the loss coefficient K, describes both flow regimes: laminar for very small Reynolds numbers and turbulent for higher Reynolds numbers (default model). The component describes both flow regimes, using an interpolation polynomial. Orifice component checking for cavitation. Simple textbook component, using a constant discharge coefficient. It is valid for turbulent flow only; severe numerical problems for laminar flow. Metering Orifice (that is, model Orifice No States with variable diameter). Same as Orifice No States, but with the equations rearranged to compute dp for given q. Differences between basic models are shown by a figure.

Connections

 Name Description Modelica ID ${\mathrm{port}}_{A}$ Layout of port where oil flows into an element ($0<{m}_{\mathrm{flow}}$, ${p}_{B}<{p}_{A}$ means $0<\mathrm{Δp}$) port_A ${\mathrm{port}}_{B}$ Hydraulic port where oil leaves the component (${m}_{\mathrm{flow}}<0$, ${p}_{B}<{p}_{A}$ means $0<\mathrm{Δp}$) port_B $\mathrm{oil}$ oil $\mathrm{commandedDiameter}$ Commanded area commandedDiameter

Parameters

 Name Default Units Description Modelica ID ${\mathrm{ΔT}}_{\mathrm{system}}$ $0$ $K$ Temperature offset from system temperature dT_system $d$ $0.01$ $m$ Diameter of fixed orifice diameter ${k}_{\mathrm{f1}}$ $10$ Laminar part of fixed orifice model kf1 ${k}_{\mathrm{f2}}$ $2$ Turbulent part fixed orifice, ${k}_{2}=\frac{1}{{C}_{d}^{2}}$ kf2 ${\mathrm{kv}}_{1}$ $10$ Laminar part of variable orifice model kv1 ${\mathrm{kv}}_{2}$ $2$ Turbulent part variable orifice, ${k}_{2}=\frac{1}{{C}_{d}^{2}}$ kv2 ${p}_{\mathrm{initial}}$ ${10}^{5}$ Initial pressure between Orifices p_initial