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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 Properties 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.

 

Equations

Variables

Connections

Parameters

Equations

ν=Modelica.Media.Air.MoistAir.Utilities.spliceFunctionx=Δp,pos=νoilp=pAabs,T=T,vair=vgasoil,psat=psat,neg=νoilp=pBabs,T=T,vair=vgasoil,psat=psat,Δx=100

ρ=Modelica.Media.Air.MoistAir.Utilities.spliceFunctionx=Δp,pos=ρoilp=pAabs,T=T,vair=vgasoil,psat=psat,neg=ρoilp=pBabs,T=T,vair=vgasoil,psat=psat,Δx=100

T=T0oil+ΔTsystem

q=mflowAρ

Δp=pAlimitedpBlimited

pAabs=pA+patmoil

pAlimited=maxpA,pvapouroilpatmoil

pBabs=pB+patmoil

pBlimited=maxpB,pvapouroilpatmoil

Variables

Name

Value

Units

Description

Modelica ID

Δp

 

Pa

Pressure drop

dp

q

 

m3s

Flow rate flowing into port_A

q

pAlimited

 

Pa

Limited gauge pressure

pA_limited

pBlimited

 

Pa

Limited gauge pressure

pB_limited

ρ

 

kgm3

Upstream density

rho

ν

 

m2s

Upstream kinematic viscosity

nu

pAabs

 

Pa

Absolute pressure pA

pA_abs

pBabs

 

Pa

Absolute pressure pB

pB_abs

T

 

K

Local temperature

T

pAsummary

pA

Pa

Pressure at port A

summary_pA

pBsummary

pB

Pa

Pressure at port B

summary_pB

Δpsummary

Δp

Pa

Pressure drop

summary_dp

qsummary

q

m3s

Flow rate flowing into port_A

summary_q

Phydsummary

Δpq

W

Hydraulic Power

summary_HP

psat

[1]

Pa

Gas saturation pressure

p_sat

orificeNoStates

 

 

 

orificeNoStates

meteringOriNoStates

 

 

 

meteringOriNoStates

[1] oil.gasSaturationPressureT=T,vgas=oil.vgas

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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