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MapleSim Hydraulics Library from Modelon

Var Lam Res No States  Resistance with laminar flow, variable conductance

The Var Lam Res No States component describes the laminar flow through a resistance with variable conductance. The flow rate of the resistance is given by

q=GΔp

Variables used in the above equation

q

Flow rate m3s

G

Conductance, input at signal connector as commandedConductance m3sPa

Δp

Pressure drop across resistance Pa

Equations to calculate the conductance G are given in the manual for several components. A conductance of G = 4.167e-13 m3sPa leads to a flow rate of 1 lminute at 4e7 Pa. As the critical Reynolds number depends on the component, there is no check whether the flow is actually laminar or turbulent.

Related Components

Name

Description

Lam Res No States

Resistance with laminar flow.

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).

Two Orifices

Two orifices in series, one with variable the other with fixed flow area.

Orifice N

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

 

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

G=u

T=T0oil+ΔTsystem

q=GΔp

q=mflowAρ

Δp=pAlimitedpBlimited

pAabs=pA+patmoil

pAlimited=maxpA,pvapouroilpatmoil

pBabs=pB+patmoil

pBlimited=maxpB,pvapouroilpatmoil

mflowA+mflowB=0

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

G

 

m3sPa

Conductance of laminar resistance

G

[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

u

Command

u

Parameters

Name

Default

Units

Description

Modelica ID

&Delta;Tsystem

0

K

Temperature offset from system temperature

dT_system

See Also

Lam Res No States

Metering Ori No States

Ori Cav No States

Ori Poly No States

Orifice N

Orifice No States

Restrictions

Restrictions[Basic]

Sim Ori No States

Two Orifices

MapleSim Hydraulics Library from Modelon Overview

 


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