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Check Valve

Spring-Loaded check valve

 

Description

Optional Volumes

Equations

Variables

Connections

Parameters

Description

The Check Valve component allows fluid flow in one direction, from port A to port B. The flow is controlled by an adjustable orifice whose area is controlled by the pressure difference from port A to port B.

The area increases linearly from Aclose to Aopen as the pressure increases from pclose to popen.

The pressure drop vs flow-rate, for the computed area, comes from the Orifice model.

Optional Volumes

The boolean parameters Use volume A and Use volume B, when true, add optional volumes VA  and VB to ports A and B, respectively. See Port Volumes for details.

If two orifices or valves are connected, enabling a volume at the common port reduces the the stiffness of the system and improves the solvability.

Equations

p=pApB=πρνq16q4π2Acs2ν4+Cr4144Cd2πAcsAcs

q=qAqVA

{Acs=Ai=AtExactAcs=minAopen,maxAclose,Ai,tcdAidt+Ai=Atotherwise

At&equals;{AcloseppcloseAclose&plus;ppcloseAopenAclosepopenpclosep<popenAopenotherwise

VfA&equals;{VA1&plus;pAEluseVolumeA0otherwiseVfB&equals;{VB1&plus;pBEluseVolumeB0otherwise

qVA&equals;{dVfAdtuseVolumeA0otherwiseqVB&equals;{dVfBdtuseVolumeB0otherwise

qA&plus;qBqVAqVB&equals;0

Variables

Name

Units

Description

Modelica ID

p

Pa

Pressure drop from A to B

p

Ai

m2

Filtered  interpolated area

At

At

m2

Interpolated area

At

q

m3s

Flow rate from port A to port B

q

Connections

Name

Description

Modelica ID

portA

Hydraulic port on left side

portA

portB

Hydraulic port on right side

portB

Parameters

General Parameters

Name

Default

Units

Description

Modelica ID

pclose

1.9·107

Pa

Pressure at which valve is fully closed (A = Aclose)

pclose

popen

2.05·107

Pa

Pressure at which valve is fully open (A = Aopen)

popen

Aclose

1·10−12

m2

Valve area when closed (leakage)

Aclose

Aopen

1·10−5

m2

Valve area when fully open

Aopen

Exact

false

 

When false (not checked) a first-order dynamics is used for the valve area

Exact

tc

110

s

Time constant of dynamics equation used when Exact is false

tc

Cd

710

 

Flow-discharge coefficient

Cd

Cr

12

 

Reynolds number at critical flow

ReCr

Volume Parameters

Name

Default

Units

Description

Modelica ID

Use volume A

false

 

When true a hydraulic volume chamber is added to portA

useVolumeA

VA

1·10−6

m3

Volume of chamber A

Va

Use volume B

false

 

When true a hydraulic volume chamber is added to portB

useVolumeB

VB

1·10−6

m3

Volume of chamber B

Vb

For more information see Port Volumes.

See Also

Hydraulics Library

Valves