Hot Oil Shuttle Valve
Shuttle valve which directs flow from lower pressure inlet
Description
Equations
Variables
Connections
Parameters
The Hot Oil Shuttle Valve component allows flow out of port C from the either port A or port B, depending which has the lower pressure. Based on the orifice area, the pressure vs. flow rate relationship is calculated by the formulation used in the Orifice component.
Formulation Approximate
One of two approaches can be selected for modeling the flow in the device. When the boolean parameter Use constant Cd is true, a constant coefficient of discharge (Cd) is used, otherwise a variable coefficient of discharge with maximum value (Cd⁡max) and a critical flow number (Critno) are used.
Optional Volumes
The boolean parameters Use volume A, Use volume B, and Use volume C when true, add optional volumes VA, VB, and VC to ports A, B, and C, respectively. See Port Volumes for details.
If two orifices or valves are connected, enabling a volume at the common port reduces the stiffness of the system and improves the solvability.
{pAC=π4⁢ρ⁢ν⁢qAA⁢16⁢qAA4π2⁢Acs12⁢ν4+ℜCr414Cd2⁢Acs1⁢π⁢Acs1\seConstantCdqAA=Cd⁡max⁢tanh⁡4⁢2⁢Acs1⁢pACπ⁢ρν⁢Critno⁢Acs1⁢2⁢pACρ⁢sign⁡pACotherwise
{pBC=π4⁢ρ⁢ν⁢qBB⁢16⁢qBB4π2⁢Acs22⁢ν4+ℜCr414Cd2⁢Acs2⁢π⁢Acs2\seConstantCdqBB=Cd⁡max⁢tanh⁡4⁢2⁢Acs2⁢pBCπ⁢ρν⁢Critno⁢Acs2⁢2⁢pBCρ⁢sign⁡pBCotherwise
{Acs1=Ai∧Ai=AtExactAcs1=min⁡Aopen,max⁡Aclose,Ai,tc⁢d⁢Ai⁢1d⁢t+Ai=Atotherwise
Acs2=Aopen+Aclose−Acs1
At=Aopen−Aclose⁢12−12⁢tanh⁡eps⁢pAB
VfA={Va⁢1+pAElUse volume A0otherwise qVA={V.fAUse volume A0otherwise
VfB={Vb⁢1+pBElUse volume B0otherwise qVB={V.fBUse volume B0otherwise
VfC={Vc⁢1+pCElUse volume C0otherwise qVC={V.fCUse volume C0otherwise
pAB=pA−pBpAC=pA−pCpBC=pB−pC
qAA=qA−qVAqBB=qB−qVBqCC=qC−qVC
qA+qB+qC−qVA−qVB−qVC=0
Name
Units
Modelica ID
pX
Pa
Pressure at port X
pXY
Pressure drop from port X to port Y
qXX
m3s
Flow rate into port X
qVX
Flow rate into port X's optional volume
VfX
m3
Effective volume at port X
ACS1
m2
Cross-sectional area from A to B
Acs[1]
ACS2
Cross-sectional area from B to C
Acs[2]
Ai
Filtered interpolated area
At
Interpolated area
u1
ms
Fluid velocity from A to B
u2
Fluid velocity from B to C
X,Y∈A,B,C
portA
Hydraulic port of left inlet
portB
Hydraulic port of right inlet
portC
Hydraulic port of bottom outlet
General
Default
Aclose
1·10−12
Orifice area when closed (leakage)
Aopen
1·10−5
Orifice area when fully open
ε
0.2
1Pa
Positive factor that effects the transition between ports A and B
eps
Exact
false
When false (not checked) first-order dynamics are used for the valve area
tc
0.1
s
Time constant
Orifice
Use constant Cd
true
True (checked) means a constant coefficient of discharge is implemented, otherwise a variable Cd is used in flow calculations
UseConstantCd
Cd
0.7
Flow-discharge coefficient; used when Use constant Cd is true
ReCr
12
Reynolds number at critical flow; used when Use constant Cd is true
Cd⁡max
Maximum flow-discharge coefficient; used when Use constant Cd is false
Cd_max
Critno
1000
Critical flow number; used when Use constant Cd is false
Crit_no
Use volume A
True (checked) means a hydraulic volume chamber is added to portA
useVolumeA
VA
1·10−6
Volume of chamber A
Va
Use volume B
True (checked) means a hydraulic volume chamber is added to portB
useVolumeB
VB
Volume of chamber B
Vb
Use volume C
True (checked) means a hydraulic volume chamber is added to portC
useVolumeC
VC
Volume of chamber C
Vc
For more information see Port Volumes.
See Also
Hydraulics Library
Valves
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