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MapleSim Hydraulics Library from Modelon

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 commandedDiameter m 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

Lam Res No States

Resistance with laminar flow.

Var Lam Res No States

Resistance with laminar flow and externally commanded conductance.

Orifice No States

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).

Ori Poly No States

The component describes both flow regimes, using an interpolation polynomial.

Ori Cav No States

Orifice component checking for cavitation.

Sim Ori No States

Simple textbook component, using a constant discharge coefficient. It is valid for turbulent flow only; severe numerical problems for laminar flow.

Metering Ori No States

Metering Orifice (that is, model Orifice No States with variable diameter).

Orifice N

Same as Orifice No States, but with the equations rearranged to compute dp for given q.

Restrictions[Basic]

Differences between basic models are shown by a figure.

Connections

Name

Description

Modelica ID

portA

Layout of port where oil flows into an element (0<mflow, pB<pA means 0<&Delta;p)

port_A

portB

Hydraulic port where oil leaves the component (mflow<0, pB<pA means 0<&Delta;p)

port_B

oil

 

oil

commandedDiameter

Commanded area

commandedDiameter

Parameters

Name

Default

Units

Description

Modelica ID

&Delta;Tsystem

0

K

Temperature offset from system temperature

dT_system

d

0.01

m

Diameter of fixed orifice

diameter

kf1

10

 

Laminar part of fixed orifice model

kf1

kf2

2

 

Turbulent part fixed orifice, k2&equals;1Cd2

kf2

kv1

10

 

Laminar part of variable orifice model

kv1

kv2

2

 

Turbulent part variable orifice, k2&equals;1Cd2

kv2

pinitial

105

 

Initial pressure between Orifices

p_initial

See Also

Lam Res No States, Metering Ori, Metering Ori No States, Ori Cav No States, Ori Poly No States, Orifice, Orifice N, Orifice No States, Restrictions, Restrictions[Basic], Sim Ori No States, Var Lam Res No States, MapleSim Hydraulics Library from Modelon Overview


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