4Way 2Position Directional Valve (2P)
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Directional Control Valves
Description
The 4Way 2Position Directional Valve (2P) models a valve with four openings — such as the valves between an actuator, pump, and tank — in a twophase fluid network. A single spool controls the valve operation according to the signal at port S. You can set the baseline configuration of your valve by specifying the orifices that are open when the spool moves in the positive direction and negative directions in the Positive spool position open connections and Negative spool position open connections parameters, respectively. You can set the valve opening model in the Orifice parameterization parameter as a linear relationship or function of userprovided data, which you can apply to one or all flow paths in the valve.
This block is a composite component that comprises of multiple instances of the Orifice (2P) block. Refer to the Orifice (2P) block for more details about valve parameterizations and block calculations. In some configurations, this valve resembles a 3way valve. To set additional flow paths when the spool is in the neutral position, see the 4Way 3Position Directional Valve (2P) block.
This image shows an example valve setup where the valve is connected to a tank,
actuator, and pump and the Positive spool position open connections
parameter is PB, AT
:
This image shows the valve when the Negative spool position open
connections parameter is PA, BT
:
In this configuration, when the signal at port S moves the spool to a negative position, the paths between ports P and A and between ports B and T are open to flow. The paths between ports P and B and ports A and T are closed to flow.
This image shows the valve when the Positive spool position open
connections parameter is PB, AT
:
In this configuration, when the signal at port S moves the spool to a positive position, the paths between ports P and B and between ports A and T are open to flow and the paths between ports P and A and between ports B and T are closed.
The schematic that represents this configuration is:
The lefthand side corresponds to the positive position and the righthand side corresponds to the negative position. The valve transitions through positions in the neutral midsection.
Spool Displacement and Valve Configuration
The spool stroke is the amount of spool travel an orifice takes to fully open from a closed position. You can use the Orifice parameterization and Area characteristics parameters to specify the flow path characteristics:
Orifice Parameterization  Identical for All Flow Paths  Different for Each Flow Path 

Linear  Area vs. spool
travel  The Spool travel between closed and open orifice parameter defines the spool stroke  The Spool travel between closed and open orifice parameter defines the spool stroke for each orifice 
Tabulated data  Area vs. spool
travel  The difference between the first and last element of the Spool travel vector parameter defines the spool stroke  The difference between the first and last element of the Spool travel vector parameter for each orifice 
Tabulated data  Volumetric flow rate vs. spool
travel and pressure drop or
Tabulated data  Mass flow rate vs. spool
travel and pressure drop  The difference between the first and last element of the Spool travel vector, ds parameter defines the spool stroke  The difference between the first and last element of the Spool travel vector, ds parameter defines the spool stroke for each orifice 
The direction of the spool movement depends on the spool stroke, orifice orientation, and signal at port S. This table shows the spool travel for an orifice depending on the selections for the Positive spool position open connection and Negative spool position open connection parameters:
Spool Position When Orifice Is Open  Spool Travel, ΔS 

Orifice always closed: orifice not selected for the Positive spool position open connection or Negative spool position open connection parameters  N/A 
Orifice always open: orifice selected for both the Positive spool position open connection and Negative spool position open connection parameters  N/A 
Negative: orifice selected for only Negative spool position open connection parameter  S_{orifice_max} + spool stroke – S 
Positive: orifice selected for only Positive spool position open connection parameter  S_{orifice_max} – spool stroke + S 
Where S_{orifice_max} is the spool position at the maximum orifice area defined for each orifice. The orifice area saturates at the leakage area when ΔS is negative and saturates at the maximum orifice area when the orifice is fully open. When the orifice is fully open, ΔS is equal to the spool stroke, so ΔS greater than the spool stroke does not further increase the orifice area.
This table shows the possible configurations of the 4Way 2Position Directional Valve (TL):
Configuration  Parameter Values 

All four paths are closed during transition. 

All four paths are open during transition. 

AT and BT are closed during transition. 

PA and PB are closed during transition. 

PB and BT are closed during transition. 

PA and AT are closed during transition. 

PA, PB, and BT are open during transition. 

PA, AT, and BT are open during transition. 

PA and PB are closed during transition. AT is always closed. 

All paths are closed during transition. 

AT is open during transition. PA is closed during transition. 

BT is open during transition. PB is closed during transition. 

PA is closed during transition. 

PB is closed during transition. 

Valve Orifice Parameterizations
The Modeling option parameter controls the parameterization options for a valve designed for modeling either vapor or liquid, but does not impact the fluid properties. The block calculates fluid properties inside the valve from inlet conditions.
The Orifice parameterization parameter specifies the model
for the open area or flow rate through one or all of the valve orifices. If you set
Area characteristics to Identical for all flow
paths
, the block applies the same data for all flow paths. When
you select Different for all flow paths
, the block uses
individual parameterizations for each flow path.
When Modeling option is Liquid operating
condition
, the block parameterizations are designed for a
valve controlling liquid flow.
When Orifice parameterization is Linear 
Area vs. spool travel
, the opening area is a linear function
of the spool position received as a signal at port S
$${A}_{orifice}=\frac{\left({A}_{\mathrm{max}}{A}_{leak}\right)}{\Delta {S}_{\mathrm{max}}}\Delta S+{A}_{leak},$$
where:
ΔS is the spool travel.
A_{orifice} saturates at A_{leak} when ΔS is negative and saturates at A_{max} when the orifice is fully open. When the orifice is fully open, ΔS is equal to the spool stroke, so a value of ΔS that is greater than the spool stroke does not increase the orifice area.
ΔS_{max} is the value of the Spool travel between closed and open orifice parameter.
A_{max} is the value of the Maximum orifice area parameter.
A_{leak} is the value of the Leakage area parameter.
When the valve is in a nearopen or nearclosed position in the linear parameterization, you can maintain numerical robustness in your simulation by adjusting the Smoothing factor parameter. If the Smoothing factor parameter is nonzero, the block smoothly saturates the opening area between A_{leak} and A_{max}. For more information, see Numerical Smoothing.
When Orifice parameterization is Tabulated data  Area
vs. spool travel
, you can provide spool travel vectors for
your system or for individual flow paths between ports P,
A, B, and T.
The block uses this data to calculate the relationship between the orifice area
and spool displacement. The block uses interpolation to determine the opening
area between given data points. A_{leak}
and A_{max} are the first and last
parameters of the opening area vector, respectively.
When Orifice parameterization is Tabulated
data  Nominal mass flow rate vs. spool travel
, the block
calculates the mass flow rate for each orifice from the nominal conditions you
specify in the block parameters. The spool position signal from port
S scales the orifice opening area, which can also scale
mass flow rate.
When Modeling option is Vapor operating
condition
, the block parameterizations are designed to model a
valve that controls vapor flow.
The method the block uses to control each orifice depends on the Opening characteristic parameter:
Linear
— The measure of flow capacity depends on the spool position at port S. As the spool displaces to open to orifice, the measure of flow capacity scales from the specified minimum to the specified maximum.Tabulated
— The block calculates the measure of flow capacity as a function of the spool position at port S. This function uses a onedimensional lookup table.
The Orifice parameterization parameter determines how the block calculates the flow rate in each orifice:
Cv flow coefficient
— The flow coefficient C_{v} scales the flow rate in each orifice. The flow coefficient measures the ease with which a fluid can flow when driven by a certain pressure differential.Kv flow coefficient
— The flow coefficient K_{v}, where $${K}_{v}=0.865{C}_{v}$$, scales the flow rate in each orifice. The flow coefficient measures the ease with which a fluid can flow when driven by a certain pressure differential.Orifice area
— The size of the orifice area scales the flow rate in each orifice.
Visualize Orifice Openings
To visualize the spool offsets and maximum displacement, rightclick the block and select Fluids > Plot Valve Characteristics. The plot shows the orifices specified by the parameters in Valve Configuration section. When you set the parameters in the Valve Configuration tab to the same orifice, the orifice opening is a constant.
Click Reload Data to update the data in the figure.
This image shows the default configuration for the block:
Positive spool position open connections is
PA, BT
Negative spool position open connections is
PB, AT
All other spool positions are at the default values.
Assumptions and Limitations
There is no heat exchange between the valve and the environment.
When Modeling option is
Liquid operating condition
, the results may not be accurate outside of the subcooled liquid region. When Modeling option isVapor operating condition
, the results may not be accurate outside of the superheated vapor region. To model a valve in a liquidvapor mixture, set Modeling option toLiquid operating condition
.
Ports
Conserving
A — Entry or exit port
twophase fluid
Twophase fluid conserving port associated with the entry or exit port to the valve.
B — Entry or exit port
twophase fluid
Twophase fluid conserving port associated with the entry or exit port to the valve.
P — Entry or exit port
twophase fluid
Twophase fluid conserving port associated with the entry or exit port to the valve.
T — Entry or exit port
twophase fluid
Twophase fluid conserving port associated with the entry or exit port to the valve.
Input
S — Spool displacement, m
physical signal
Physical signal associated with the spool displacement, in m.
Parameters
Modeling option — Modeling option for fluid phase
Liquid operating
condition
(default)  Vapor operating condition
Modeling option for the fluid phase at the valve. Set this parameter to
Liquid operating condition
if the twophase
fluid at the block location is in a liquid state. Set this parameter to
Vapor operating condition
if the twophase
fluid at the block location is in a vapor state.
Valve Configuration
Positive spool position open connections — Flow paths open when spool is in positive position
PA, BT
(default)  PA, PB
 PB, AT
 PA
 PB
 PA, PB, AT, BT
Flow paths open when the spool is in a positive position. This parameter sets the valve configuration and defines the direction of spool movement according to the signal received at port S.
Negative spool position open connections — Flow paths open when spool moves in negative direction
PB, AT
(default)  PA, BT
 PA, PB
 PA
 PB
 PA, PB, AT, BT
Flow paths open when the spool moves in the negative direction. This parameter sets the valve configuration and defines the direction of spool movement according to the signal received at port S.
Model Parameterization
Area characteristics — Flow equations for orifices
Identical for all flow
paths
(default)  Different for each flow path
Whether to apply uniform or individual flow equations for the valve
orifice area. When you set this parameter to Identical for
all flow paths
, the block uses the same orifice and
spool geometries, flow rates, pressure, and area vectors for all valve
orifices. When you set this parameter to Different for each
flow path
, you can specify these parameters
individually for each orifice. For both settings, orifices
A, B,
P, and T have the same
crosssectional areas, discharge coefficients, and Reynolds numbers when
you set Orifice parameterization to
Linear  Area vs. spool travel
or
Tabulated data  Area vs. spool travel
.
Orifice parameterization — Variable or constant orifice parameterization
Linear  Area vs. spool
travel
(default)  Linear  Nominal mass flow rate vs. spool
travel
 Tabulated data  Area vs. spool
travel
 Cv flow coefficient
 Kv flow coefficient
 Orifice area
Method the block uses to calculate the mass flow rate from the pressure difference across the orifice or the pressure difference from the mass flow rate.
When Modeling option is Liquid
operating condition
, the choices for this parameter are:
Linear  Area vs. spool travel
Linear  Nominal mass flow rate vs. spool travel
Tabulated data  Area vs. spool travel
When Modeling option is Vapor
operating condition
, the choices for this parameter are:
Cv flow coefficient
Kv flow coefficient
Orifice area
Spool travel between closed and open orifice — Maximum spool stroke
0.005 m
(default)  positive scalar
Maximum distance of spool travel.
Dependencies
To enable this parameter, set Area
characteristics to Identical for all
flow paths
and either:
Modeling option to
Liquid operating condition
and Orifice parameterization toLinear  Area vs. spool travel
.Modeling option to
Vapor operating condition
and Opening characteristic toLinear
.
Maximum orifice area — Maximum orifice opening area
1e4 m^2
(default)  positive scalar
Largest open area of each orifice during the operation of the valve.
Dependencies
To enable this parameter, set Area
characteristics to Identical for all
flow paths
and either:
Modeling option to
Liquid operating condition
and Orifice parameterization toLinear  Area vs. spool travel
.Modeling option to
Vapor operating condition
, Orifice parameterization toOrifice area
, and Opening characteristic toLinear
.
Nominal mass flow rate at maximum orifice opening — Rated mass flow rate
0.1
kg/s (default)  positive scalar
Typical, rated, or design mass flow rate at the orifice maximum opening position.
Dependencies
To enable this parameter, set Modeling option
to Liquid operating condition
,
Area characteristics to
Identical for all flow paths
, and
Orifice parameterization to
Linear  Nominal mass flow rate vs. spool
travel
.
Nominal pressure drop at maximum orifice opening — Rated pressure drop
0.001
MPa (default)  positive scalar
Typical, rated, or design pressure drop at the orifice maximum opening position.
Dependencies
To enable this parameter, set Modeling option
to Liquid operating condition
,
Area characteristics to
Identical for all flow paths
, and
Orifice parameterization to
Linear  Nominal mass flow rate vs. spool
travel
.
Nominal inlet condition specification — Method of determining inlet fluid state
Temperature
(default)  Vapor quality
 Vapor void fraction
 Specific enthalpy
 Specific internal energy
Method of determining the inlet fluid state. The block determines the orifice nominal inlet specific volume from the tabulated fluid properties data based on the value of the Nominal inlet pressure and Nominal inlet condition specification parameters.
Dependencies
To enable this parameter, set Modeling option
to Liquid operating condition
,
Area characteristics to
Identical for all flow paths
, and
Orifice parameterization to
Linear  Nominal mass flow rate vs. spool
travel
.
Nominal inlet pressure — Inlet fluid pressure
0.101325
MPa (default)  positive scalar
Inlet pressure in nominal conditions. The block determines the inlet specific volume from the tabulated fluid properties data based on the value of the Nominal inlet pressure and Nominal inlet condition specification parameters.
Dependencies
To enable this parameter, set Modeling option
to Liquid operating condition
,
Area characteristics to
Identical for all flow paths
, and
Orifice parameterization to
Linear  Nominal mass flow rate vs. spool
travel
.
Nominal inlet temperature — Fluid temperature
293.15
K (default)  positive scalar
Inlet fluid temperature in nominal operating conditions.
Dependencies
To enable this parameter, set Modeling option
to Liquid operating condition
,
Area characteristics to
Identical for all flow paths
,
Orifice parameterization to
Linear  Nominal mass flow rate vs. spool
travel
, and Nominal inlet condition
specification to
Temperature
.
Nominal inlet vapor quality — Inlet vapor quality mass fraction
0
(default)  positive scalar in the range [0,1]
Inlet mixture vapor quality by mass fraction in nominal operating
conditions. A value of 0
means that the inlet fluid
is subcooled liquid. A value of 1
means that the
inlet fluid is superheated vapor.
Dependencies
To enable this parameter, set Modeling option
to Liquid operating condition
,
Area characteristics to
Identical for all flow paths
,
Orifice parameterization to
Linear  Nominal mass flow rate vs. spool
travel
, and Nominal inlet condition
specification to Vapor
quality
.
Nominal inlet vapor void fraction — Inlet volume fraction
0
(default)  positive scalar in the range [0,1]
Inlet mixture volume fraction in nominal operating conditions. A value
of 0
means that the inlet fluid is subcooled liquid.
A value of 1
means that the inlet fluid is
superheated vapor.
Dependencies
To enable this parameter, set Modeling option
to Liquid operating condition
,
Area characteristics to
Identical for all flow paths
,
Orifice parameterization to
Linear  Nominal mass flow rate vs. spool
travel
, and Nominal inlet condition
specification to Vapor void
fraction
.
Nominal inlet specific enthalpy — Inlet fluid specific enthalpy
400
kJ/kg (default)  positive scalar
Inlet specific enthalpy in nominal operating conditions.
Dependencies
To enable this parameter, set Modeling option
to Liquid operating condition
,
Area characteristics to
Identical for all flow paths
,
Orifice parameterization to
Linear  Nominal mass flow rate vs. spool
travel
, and Nominal inlet condition
specification to Specific
enthalpy
.
Nominal inlet specific internal energy — Inlet specific internal energy
400
kJ/kg (default)  positive scalar
Inlet specific internal energy in nominal operating conditions.
Dependencies
To enable this parameter, set Modeling option
to Liquid operating condition
,
Area characteristics to
Identical for all flow paths
,
Orifice parameterization to
Linear  Nominal mass flow rate vs. spool
travel
, and Nominal inlet condition
specification to Specific internal
energy
.
Opening characteristic — Method to convert control signal to measure of flow capacity
Linear
(default)  Tabulated
Method by which to convert the control signal specified at port S to the chosen measure of flow capacity.
Dependencies
To enable this parameter, set Modeling option
to Vapor operating condition
.
Spool travel vector — Vector of spool opening distances relative to fully closed position
[0, .00125, .0025, .00375, .005]
m
(default)  1byn vector
Vector of spool travel distances when parameterizing the orifice according to the tabulated valve area data. The vector elements must correspond onetoone with the elements in the Orifice area vector parameter. List the values in ascending order. The first element must be 0. The block uses linear interpolation between table data points.
Dependencies
To enable this parameter, set Area
characteristics to Identical for all
flow paths
and either:
Modeling option to
Liquid operating condition
and Orifice parameterization toTabulated data  Area vs. spool travel
.Modeling option to
Vapor operating condition
and Opening characteristic toTabulated
.
Orifice area vector — Vector of valve opening areas
[1e10, 1e05, 4e05, 6e05, .0001]
m^2
(default)  1byn vector
Vector of opening areas when parameterizing the orifice according to the tabulated valve area data. The vector elements must correspond onetoone with the elements in the Spool travel vector parameter. List the values in ascending order. The elements must be greater than 0.
Dependencies
To enable this parameter, set Area
characteristics to Identical for all
flow paths
and either:
Modeling option to
Liquid operating condition
and Orifice parameterization toTabulated data  Area vs. spool travel
.Modeling option to
Vapor operating condition
, Orifice parameterization toOrifice area
, and Opening characteristic toTabulated
.
Maximum Cv flow coefficient — C_{v} coefficient that corresponds to maximally open component
4
(default)  positive scalar
Value of the C_{v} flow coefficient when the orifice is fully open and the area available for flow is at a maximum. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential.
Dependencies
To enable this parameter, set Modeling option
to Vapor operating condition
,
Area characteristics to
Identical for all flow paths
,
Orifice parameterization to Cv
flow coefficient
, and Opening
characteristic to
Linear
.
Cv flow coefficient vector — C_{v} coefficients for values in member position vector
[1e06, .8, 1.6, 2.4, 3.2, 4]
(default)  1byn vector
Vector of C_{v} flow coefficients. Each coefficient corresponds to a value in the Control member position vector parameter. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential. The size of the vector must be the same as the Control member position vector parameter.
Dependencies
To enable this parameter, set Modeling option
to Vapor operating condition
,
Area characteristics to
Identical for all flow paths
,
Orifice parameterization to Cv
flow coefficient
, and Opening
characteristic to
Tabulated
.
Maximum Kv flow coefficient — K_{v} coefficient that corresponds to maximally open component
3.6
(default)  positive scalar
Value of the K_{v} flow coefficient when the orifice is fully open and the area available for flow is at a maximum. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential.
Dependencies
To enable this parameter, set Modeling option
to Vapor operating condition
,
Area characteristics to
Identical for all flow paths
,
Orifice parameterization to Kv
flow coefficient
, and Opening
characteristic to
Linear
.
Kv flow coefficient vector — K_{v} coefficients for values in member position vector
[1e06, .72, 1.44, 2.16, 2.88, 3.6]
(default)  1byn vector
Vector of K_{v} flow coefficients. Each coefficient corresponds to a value in the Control member position vector parameter. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential. The size of the vector must be the same as the Control member position vector parameter.
Dependencies
To enable this parameter, set Modeling option
to Vapor operating condition
,
Area characteristics to
Identical for all flow paths
,
Orifice parameterization to Kv
flow coefficient
, and Opening
characteristic to
Tabulated
.
xT pressure differential ratio factor at choked flow — Ratio of pressure differentials
0.7
(default)  positive scalar
Ratio between the inlet pressure, p_{in}, and the outlet pressure, p_{out}, defined as $$({p}_{in}{p}_{out})/{p}_{in}$$ where choking first occurs.
Dependencies
To enable this parameter, Modeling option to
Vapor operating condition
,
Area characteristics to
Identical for all flow paths
, and
Orifice parameterization to Cv
flow coefficient
or Kv flow
coefficient
.
Discharge coefficient — Discharge coefficient
0.64
(default)  positive scalar
Correction factor that accounts for discharge losses in theoretical flows.
Dependencies
To enable this parameter, set Modeling option
to Vapor operating condition
and
Orifice parameterization to
Orifice area
or set
Modeling option to Liquid
operating condition
and Orifice
parameterization to either:
Linear  Area vs. spool travel
Tabulated data  Area vs. spool travel
Leakage flow fraction — Ratio of flow rates
1e6
(default)  positive scalar
Ratio of the flow rate of the orifice when it is closed to when it is open.
Dependencies
To enable this parameter, set either:
Modeling option to
Liquid operating condition
and Orifice parameterization toLinear  Area vs. spool travel
.Modeling option to
Vapor operating condition
and Opening characteristic toLinear
.
Smoothing factor — Numerical smoothing factor
0.01
(default)  positive scalar in the range of [0,1]
Continuous smoothing factor that introduces a layer of gradual change based on the flow response when the valve is in the nearopen and nearclosed positions. To increase the stability of your simulation in these regimes, set this parameter to a nonzero value less than one.
Dependencies
To enable this parameter, set Modeling option
to Liquid operating condition
and
Orifice parametrization to
Linear  area vs. spool travel
or set
Modeling option to Vapor
operating condition
and Opening
characteristic to
Linear
.
Pressure recovery — Whether to account for pressure increase in area expansions
off
(default)  on
Whether to account for pressure increase when fluid flows from a region of smaller crosssectional area to a region of larger crosssectional area.
Dependencies
To enable this parameter, set Modeling option
to Liquid operating condition
and
Orifice parameterization to either:
Linear  area vs. spool travel
Tabulated data  Area vs. spool travel
Laminar flow pressure ratio — Laminarturbulent transition pressure ratio
0.999
(default)  positive scalar
Ratio of the orifice outlet pressure to orifice inlet pressure at which the fluid transitions between the laminar and turbulent regimes. The pressure loss corresponds to the mass flow rate linearly in laminar flows and quadratically in turbulent flows.
Inlet phase change time constant — Time lag for mixture specific volume
0.1
s
(default)  positive scalar
Time lag for liquidvapor mixtures when computing the fluid specific volume. This parameter does not influence the specific volume when the inlet fluid is a fully supercooled liquid or fully superheated vapor.
Dependencies
To enable this parameter, set Modeling option
to Liquid operating condition
.
Crosssectional area at ports P, T, A and B — Area at conserving ports
0.01 m^2
(default)  positive scalar
Maximum crosssectional areas at the entry and exit ports P, T, A, and B, which the block uses in the pressureflow rate equation that determines the mass flow rate through the valve.
PA Orifice
Spool position at maximum PA orifice area — Spool offset for fully open PA orifice
5e3 m
(default)  positive scalar
Spool offset from the neutral position for a fully open PA orifice.
Dependencies
To enable this parameter, set one of these parameters.
Set Positive spool position open connections to:
PA, BT
PA, PB
PA
PA, PB, AT, BT
or set Negative spool position open connections to:
PA, BT
PA, PB
PA
PA, PB, AT, BT
Note:
This parameter is enabled only when the PA orifice settings do not appear in both the Positive spool position open connections and Negative spool position open connections parameters.
PA spool travel between closed and open orifice — Maximum spool stroke
0.005 m
(default)  positive scalar
Maximum distance of spool travel. This value provides an upper limit to calculations so that simulations do not return unphysical values.
Dependencies
To enable this parameter, set one of the following parameters:
Positive spool position open connections to:
PA, BT
PA, PB
PA
PA, PB, AT, BT
Negative spool position open connections to:
PA, BT
PA, PB
PA
PA, PB, AT, BT
And either:
Modeling option to
Liquid operating condition
, Area characteristics toDifferent for each flow path
, and Orifice parameterization toLinear  Area vs. spool travel
orLinear  Nominal mass flow rate vs. spool travel
.Modeling option to
Vapor operating condition
, Area characteristics toDifferent for each flow path
, and Opening characteristic toLinear
.
PA nominal mass flow rate at maximum orifice opening — Rated mass flow rate
0.1
kg/s
(default)  positive scalar
Typical, rated, or design mass flow rate through a maximally open PA orifice.
Dependencies
To enable this parameter, set:
Modeling option to
Liquid operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Linear  Nominal mass flow rate vs. spool travel
One of the following parameters:
Positive spool position open connections to:
PA, BT
PA, PB
PA
PA, PB, AT, BT
Negative spool position open connections to:
PA, BT
PA, PB
PA
PA, PB, AT, BT
PA nominal pressure drop at maximum orifice opening — Rated pressure drop
0.001
MPa
(default)  positive scalar
Typical, rated, or design pressure drop through a maximally open PA orifice.
Dependencies
To enable this parameter, set:
Modeling option to
Liquid operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Linear  Nominal mass flow rate vs. spool travel
One of the following parameters:
Positive spool position open connections to:
PA, BT
PA, PB
PA
PA, PB, AT, BT
Negative spool position open connections to:
PA, BT
PA, PB
PA
PA, PB, AT, BT
PA nominal inlet condition specification — Method of determining inlet fluid state
Temperature
(default)  Vapor quality
 Vapor void fraction
 Specific enthalpy
 Specific internal energy
Method of determining the inlet fluid state for PA orifice.
Dependencies
To enable this parameter, set:
Modeling option to
Liquid operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Linear  Nominal mass flow rate vs. spool travel
At least one of the following parameters:
Positive spool position open connections to:
PA, BT
PA, PB
PA
PA, PB, AT, BT
Negative spool position open connections to:
PA, BT
PA, PB
PA
PA, PB, AT, BT
PA nominal inlet pressure — Inlet fluid pressure
0.101325
MPa
(default)  positive scalar
Inlet pressure for the PA orifice at nominal conditions.
Dependencies
To enable this parameter, set:
Modeling option to
Liquid operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Linear  Nominal mass flow rate vs. spool travel
At least one of the following parameters:
Positive spool position open connections to:
PA, BT
PA, PB
PA
PA, PB, AT, BT
Negative spool position open connections to:
PA, BT
PA, PB
PA
PA, PB, AT, BT
PA nominal inlet temperature — Fluid temperature
293.15
K
(default)  positive scalar
Inlet fluid temperature for the PA orifice in nominal operating conditions.
Dependencies
To enable this parameter, set:
Modeling option to
Liquid operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Linear  Nominal mass flow rate vs. spool travel
Nominal inlet condition specification to
Temperature
At least one of the following parameters:
Positive spool position open connections to:
PA, BT
PA, PB
PA
PA, PB, AT, BT
Negative spool position open connections to:
PA, BT
PA, PB
PA
PA, PB, AT, BT
PA nominal inlet vapor quality — Inlet vapor quality mass fraction
0
(default)  positive scalar in the range [0,1]
Inlet mixture vapor quality by mass fraction for the PA orifice in nominal operating
conditions. A value of 0
means that the inlet fluid
is subcooled liquid. A value of 1
means that the
inlet fluid is superheated vapor.
Dependencies
To enable this parameter, set:
Modeling option to
Liquid operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Linear  Nominal mass flow rate vs. spool travel
Nominal inlet condition specification to
Vapor quality
At least one of the following parameters:
Positive spool position open connections to:
PA, BT
PA, PB
PA
PA, PB, AT, BT
Negative spool position open connections to:
PA, BT
PA, PB
PA
PA, PB, AT, BT
PA nominal inlet vapor void fraction — Inlet vapor void fraction
0
(default)  positive scalar in the range [0,1]
Inlet mixture vapor void fraction for the PA orifice in nominal operating conditions.
A value of 0
means that the inlet fluid is subcooled
liquid. A value of 1
means that the inlet fluid is
superheated vapor.
Dependencies
To enable this parameter, set:
Modeling option to
Liquid operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Linear  Nominal mass flow rate vs. spool travel
Nominal inlet condition specification to
Vapor void fraction
At least one of the following parameters:
Positive spool position open connections to:
PA, BT
PA, PB
PA
PA, PB, AT, BT
Negative spool position open connections to:
PA, BT
PA, PB
PA
PA, PB, AT, BT
PA nominal inlet specific enthalpy — Inlet fluid specific enthalpy
400
kJ/kg
(default)  positive scalar
Inlet specific enthalpy for the PA orifice in nominal operating conditions.
Dependencies
To enable this parameter, set:
Modeling option to
Liquid operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Linear  Nominal mass flow rate vs. spool travel
Nominal inlet condition specification to
Specific enthalpy
At least one of the following parameters:
Positive spool position open connections to:
PA, BT
PA, PB
PA
PA, PB, AT, BT
Negative spool position open connections to:
PA, BT
PA, PB
PA
PA, PB, AT, BT
PA nominal inlet specific internal energy — Inlet specific internal energy
400
kJ/kg
(default)  positive scalar
Inlet specific internal energy for the PA orifice in nominal operating conditions.
Dependencies
To enable this parameter, set:
Modeling option to
Liquid operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Linear  Nominal mass flow rate vs. spool travel
Nominal inlet condition specification to
Specific internal energy
At least one of the following parameters:
Positive spool position open connections to:
PA, BT
PA, PB
PA
PA, PB, AT, BT
Negative spool position open connections to:
PA, BT
PA, PB
PA
PA, PB, AT, BT
PA constant orifice nominal mass flow rate — Nominal mass flow rate
0.1
kg/s
(default)  positive scalar
Typical, rated, or design mass flow rate through a constant PA orifice.
Dependencies
To enable this parameter, set:
Modeling option to
Liquid operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Linear  Nominal mass flow rate vs. spool travel
One of the following settings in each parameter:
Positive spool position open connections to:
PA, BT
PA, PB
PA
PA, PB, AT, BT
Negative spool position open connections to:
PA, BT
PA, PB
PA
PA, PB, AT, BT
Note:
This parameter is enabled only when the PA orifice settings appear in both the Positive spool position open connections and Negative spool position open connections parameters.
PA constant orifice nominal pressure drop — Nominal pressure drop
0.001
MPa
(default)  positive scalar
Typical, rated, or design pressure drop through a constant PA orifice.
Dependencies
To enable this parameter, set:
Modeling option to
Liquid operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Linear  Nominal mass flow rate vs. spool travel
One of the following settings in each parameter:
Positive spool position open connections to:
PA, BT
PA, PB
PA
PA, PB, AT, BT
Negative spool position open connections to:
PA, BT
PA, PB
PA
PA, PB, AT, BT
Note:
This parameter is enabled only when the PA orifice settings appear in both the Positive spool position open connections and Negative spool position open connections parameters.
PA constant orifice Cv flow coefficient — Flow coefficient
4
(default)  positive scalar
Value of the constant C_{v} flow coefficient for the PA orifice. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential.
Dependencies
To enable this parameter, set:
Modeling option to
Vapor operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Cv flow coefficient
One of the following settings in each parameter:
Positive spool position open connections to:
PA, BT
PA, PB
PA
PA, PB, AT, BT
Negative spool position open connections to:
PA, BT
PA, PB
PA
PA, PB, AT, BT
Note:
This parameter is enabled only when the PA orifice settings appear in both the Positive spool position open connections and Negative spool position open connections parameters.
PA orifice maximum Cv flow coefficient — C_{v} coefficient that corresponds to maximally open component
4
(default)  positive scalar
Value of the C_{v} flow coefficient when the PA orifice is fully open and the area available for flow is at a maximum. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential.
Dependencies
To enable this parameter, set:
Modeling option to
Vapor operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Cv flow coefficient
Opening characteristic to
Linear
One of the following parameters:
Positive spool position open connections to:
PA, BT
PA, PB
PA
PA, PB, AT, BT
Negative spool position open connections to:
PA, BT
PA, PB
PA
PA, PB, AT, BT
PA orifice Cv flow coefficient vector — C_{v} coefficients for values in member position vector
[1e06, .8, 1.6, 2.4, 3.2, 4]
(default)  1byn vector
Vector of C_{v} flow coefficients. Each coefficient corresponds to a value in the PA orifice spool travel vector parameter. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential. The size of the vector must be the same as the PA orifice spool travel vector parameter.
Dependencies
To enable this parameter, set:
Modeling option to
Vapor operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Cv flow coefficient
Opening characteristic to
Tabulated
One of the following parameters:
Positive spool position open connections to:
PA, BT
PA, PB
PA
PA, PB, AT, BT
Negative spool position open connections to:
PA, BT
PA, PB
PA
PA, PB, AT, BT
PA constant orifice Kv flow coefficient — Flow coefficient
3.6
(default)  positive scalar
Value of the constant K_{v} flow coefficient for the PA orifice. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential.
Dependencies
To enable this parameter, set:
Modeling option to
Vapor operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Kv flow coefficient
One of the following settings in each parameter:
Positive spool position open connections to:
PA, BT
PA, PB
PA
PA, PB, AT, BT
Negative spool position open connections to:
PA, BT
PA, PB
PA
PA, PB, AT, BT
Note:
This parameter is enabled only when the PA orifice settings appear in both the Positive spool position open connections and Negative spool position open connections parameters.
PA orifice maximum Kv flow coefficient — K_{v} coefficient that corresponds to maximally open component
3.6
(default)  positive scalar
Value of the K_{v} flow coefficient when the PA orifice is fully open and the area available for flow is at a maximum. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential.
Dependencies
To enable this parameter, set:
Modeling option to
Vapor operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Kv flow coefficient
Opening characteristic to
Linear
One of the following parameters:
Positive spool position open connections to:
PA, BT
PA, PB
PA
PA, PB, AT, BT
Negative spool position open connections to:
PA, BT
PA, PB
PA
PA, PB, AT, BT
PA orifice Kv flow coefficient vector — K_{v} coefficients for values in member position vector
[1e06, .72, 1.44, 2.16, 2.88, 3.6]
(default)  1byn vector
Vector of K_{v} flow coefficients. Each coefficient corresponds to a value in the PA orifice spool travel vector parameter. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential. The size of the vector must be the same as the PA orifice spool travel vector parameter.
Dependencies
To enable this parameter, set:
Modeling option to
Vapor operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Kv flow coefficient
Opening characteristic to
Tabulated
One of the following parameters:
Positive spool position open connections to:
PA, BT
PA, PB
PA
PA, PB, AT, BT
Negative spool position open connections to:
PA, BT
PA, PB
PA
PA, PB, AT, BT
PA orifice spool travel vector — Vector of spool opening distances relative to fully closed position
[0, .00125, .0025, .00375, .005]
m
(default)  1byn vector
Vector of spool travel distances for the tabular parameterization of the valve area. List the values in ascending order. The first element must be 0. The block uses linear interpolation between table data points.
Dependencies
To enable this parameter, set one of the following parameters:
Positive spool position open connections to:
PA, BT
PA, PB
PA
PA, PB, AT, BT
Negative spool position open connections to:
PA, BT
PA, PB
PA
PA, PB, AT, BT
And either:
Modeling option to
Liquid operating condition
, Area characteristics toDifferent for each flow path
, and Orifice parameterization toTabulated data  Area vs. spool travel
.Modeling option to
Vapor operating condition
, Area characteristics toDifferent for each flow path
, and Opening characteristic toTabulated
.
PA maximum orifice area — Maximum orifice opening area
1e4 m^2
(default)  positive scalar
Largest open area of the PA orifice during the operation of the valve.
Dependencies
To enable this parameter, set one of the following parameters:
Positive spool position open connections to:
PA, BT
PA, PB
PA
PA, PB, AT, BT
Negative spool position open connections to:
PA, BT
PA, PB
PA
PA, PB, AT, BT
Also set Area characteristics to
Different for each flow path
and
either:
Modeling option to
Liquid operating condition
and Orifice parameterization toLinear  Area vs. spool travel
.Modeling option to
Vapor operating condition
, Orifice parameterization toOrifice area
, and Opening characteristic toLinear
.
PA orifice area vector — Vector of valve opening areas
[1e10, 1e05, 4e05, 6e05, .0001]
m^2
(default)  1byn vector
Vector of opening areas for the tabular parameterization of the valve area. The vector elements must correspond onetoone with the elements in the PA orifice spool travel vector parameter. The elements must be greater than 0 and listed in ascending order.
Dependencies
To enable this parameter, set one of the following parameters:
Positive spool position open connections to:
PA, BT
PA, PB
PA
PA, PB, AT, BT
Negative spool position open connections to:
PA, BT
PA, PB
PA
PA, PB, AT, BT
Also set Area characteristics to
Different for each flow path
and
either:
Modeling option to
Liquid operating condition
and Orifice parameterization toTabulated data  Area vs. spool travel
.Modeling option to
Vapor operating condition
, Orifice parameterization toOrifice area
, and Opening characteristic toTabulated
.
PA constant orifice area — Crosssectional area for constant orifice
1e4 m^2
(default)  positive scalar
Orifice area when the positive and negative spool positions include the same orifice.
Dependencies
To enable this parameter, set one of the following settings in each parameter:
Positive spool position open connections to:
PA, BT
PA, PB
PA
PA, PB, AT, BT
Negative spool position open connections to:
PA, BT
PA, PB
PA
PA, PB, AT, BT
And either:
Modeling option to
Liquid operating condition
, Area characteristics toDifferent for each flow path
, and Orifice parameterization toTabulated data  Area vs. spool travel
orLinear  Area vs. spool travel
.Modeling option to
Vapor operating condition
, Area characteristics toDifferent for each flow path
, and Opening characteristic toTabulated
.
Note:
This parameter is enabled only when the PA orifice settings appear in both the Positive spool position open connections and Negative spool position open connections parameters.
PA orifice xT pressure differential ratio factor at choked flow — Ratio of pressure differentials
0.7
(default)  positive scalar
Ratio between the inlet pressure, p_{in}, and the outlet pressure, p_{out}, defined as $$({p}_{in}{p}_{out})/{p}_{in}$$ where choking first occurs for the PA orifice.
Dependencies
To enable this parameter, set:
Modeling option to
Vapor operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Kv flow coefficient
orCv flow coefficient
At least one of the following parameters:
Positive spool position open connections to:
PA, BT
PA, PB
PA
PA, PB, AT, BT
Negative spool position open connections to:
PA, BT
PA, PB
PA
PA, PB, AT, BT
PB Orifice
Spool position at maximum PB orifice area — Spool offset for fully open PB orifice
5e3 m
(default)  positive scalar
Spool offset from the neutral position for a fully open PB orifice.
Dependencies
To enable this parameter, set one of these parameters:
Positive spool position open connections to:
PB, AT
PA, PB
PB
PA, PB, AT, BT
or set Negative spool position open connections to:
PB, AT
PA, PB
PB
PA, PB, AT, BT
Note:
This parameter is enabled only when the PB orifice settings do not appear in both the Positive spool position open connections and Negative spool position open connections parameters.
PB spool travel between closed and open orifice — Maximum spool stroke
0.005 m
(default)  positive scalar
Maximum distance of spool travel. This value provides an upper limit to calculations so that simulations do not return unphysical values.
Dependencies
To enable this parameter, set one of the following parameters:
Positive spool position open connections to:
PB, AT
PA, PB
PB
PA, PB, AT, BT
Negative spool position open connections to:
PB, AT
PA, PB
PB
PA, PB, AT, BT
And either:
Modeling option to
Liquid operating condition
, Area characteristics toDifferent for each flow path
, and Orifice parameterization toLinear  Area vs. spool travel
orLinear  Nominal mass flow rate vs. spool travel
.Modeling option to
Vapor operating condition
, Area characteristics toDifferent for each flow path
, and Opening characteristic toLinear
.
PB nominal mass flow rate at maximum orifice opening — Rated mass flow rate
0.1
kg/s
(default)  positive scalar
Typical, rated, or design mass flow rate through a maximally open PB orifice.
Dependencies
To enable this parameter, set:
Modeling option to
Liquid operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Linear  Nominal mass flow rate vs. spool travel
One of the following parameters:
Positive spool position open connections to:
PB, AT
PA, PB
PB
PA, PB, AT, BT
Negative spool position open connections to:
PB, AT
PA, PB
PB
PA, PB, AT, BT
PB nominal pressure drop at maximum orifice opening — Rated pressure drop
0.001
MPa
(default)  positive scalar
Typical, rated, or design pressure drop through a maximally open PB orifice.
Dependencies
To enable this parameter, set:
Modeling option to
Liquid operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Linear  Nominal mass flow rate vs. spool travel
One of the following parameters:
Positive spool position open connections to:
PB, AT
PA, PB
PB
PA, PB, AT, BT
Negative spool position open connections to:
PB, AT
PA, PB
PB
PA, PB, AT, BT
PB nominal inlet condition specification — Method of determining inlet fluid state
Temperature
(default)  Vapor quality
 Vapor void fraction
 Specific enthalpy
 Specific internal energy
Method of determining the inlet fluid state for PB orifice.
Dependencies
To enable this parameter, set:
Modeling option to
Liquid operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Linear  Nominal mass flow rate vs. spool travel
At least one of the following parameters:
Positive spool position open connections to:
PB, AT
PA, PB
PB
PA, PB, AT, BT
Negative spool position open connections to:
PB, AT
PA, PB
PB
PA, PB, AT, BT
PB nominal inlet pressure — Inlet fluid pressure
0.101325
MPa
(default)  positive scalar
Inlet pressure for the PB orifice at nominal conditions.
Dependencies
To enable this parameter, set:
Modeling option to
Liquid operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Linear  Nominal mass flow rate vs. spool travel
At least one of the following parameters:
Positive spool position open connections to:
PB, AT
PA, PB
PB
PA, PB, AT, BT
Negative spool position open connections to:
PB, AT
PA, PB
PB
PA, PB, AT, BT
PB nominal inlet temperature — Fluid temperature
293.15
K
(default)  positive scalar
Inlet fluid temperature for the PB orifice in nominal operating conditions.
Dependencies
To enable this parameter, set:
Modeling option to
Liquid operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Linear  Nominal mass flow rate vs. spool travel
Nominal inlet condition specification to
Temperature
At least one of the following parameters:
Positive spool position open connections to:
PB, AT
PA, PB
PB
PA, PB, AT, BT
Negative spool position open connections to:
PB, AT
PA, PB
PB
PA, PB, AT, BT
PB nominal inlet vapor quality — Inlet vapor quality mass fraction
0
(default)  positive scalar in the range [0,1]
Inlet mixture vapor quality by mass fraction for the PB orifice in nominal operating
conditions. A value of 0
means that the inlet fluid
is subcooled liquid. A value of 1
means that the
inlet fluid is superheated vapor.
Dependencies
To enable this parameter, set:
Modeling option to
Liquid operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Linear  Nominal mass flow rate vs. spool travel
Nominal inlet condition specification to
Vapor quality
At least one of the following parameters:
Positive spool position open connections to:
PB, AT
PA, PB
PB
PA, PB, AT, BT
Negative spool position open connections to:
PB, AT
PA, PB
PB
PA, PB, AT, BT
PB nominal inlet vapor void fraction — Inlet vapor void fraction
0
(default)  positive scalar in the range [0,1]
Inlet mixture vapor void fraction for the PB orifice in nominal operating conditions. A
value of 0
means that the inlet fluid is subcooled
liquid. A value of 1
means that the inlet fluid is
superheated vapor.
Dependencies
To enable this parameter, set:
Modeling option to
Liquid operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Linear  Nominal mass flow rate vs. spool travel
Nominal inlet condition specification to
Vapor void fraction
At least one of the following parameters:
Positive spool position open connections to:
PB, AT
PA, PB
PB
PA, PB, AT, BT
Negative spool position open connections to:
PB, AT
PA, PB
PB
PA, PB, AT, BT
PB nominal inlet specific enthalpy — Inlet fluid specific enthalpy
400
kJ/kg
(default)  positive scalar
Inlet specific enthalpy for the PB orifice in nominal operating conditions.
Dependencies
To enable this parameter, set:
Modeling option to
Liquid operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Linear  Nominal mass flow rate vs. spool travel
Nominal inlet condition specification to
Specific enthalpy
At least one of the following parameters:
Positive spool position open connections to:
PB, AT
PA, PB
PB
PA, PB, AT, BT
Negative spool position open connections to:
PB, AT
PA, PB
PB
PA, PB, AT, BT
PB nominal inlet specific internal energy — Inlet specific internal energy
400
kJ/kg
(default)  positive scalar
Inlet specific internal energy for the PB orifice in nominal operating conditions.
Dependencies
To enable this parameter, set:
Modeling option to
Liquid operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Linear  Nominal mass flow rate vs. spool travel
Nominal inlet condition specification to
Specific internal energy
At least one of the following parameters:
Positive spool position open connections to:
PB, AT
PA, PB
PB
PA, PB, AT, BT
Negative spool position open connections to:
PB, AT
PA, PB
PB
PA, PB, AT, BT
PB constant orifice nominal mass flow rate — Nominal mass flow rate
0.1
kg/s
(default)  positive scalar
Typical, rated, or design mass flow rate through a constant PB orifice.
Dependencies
To enable this parameter, set:
Modeling option to
Liquid operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Linear  Nominal mass flow rate vs. spool travel
One of the following settings in each parameter:
Positive spool position open connections to:
PB, AT
PA, PB
PB
PA, PB, AT, BT
Negative spool position open connections to:
PB, AT
PA, PB
PB
PA, PB, AT, BT
Note:
This parameter is enabled only when the PB orifice settings appear in both the Positive spool position open connections and Negative spool position open connections parameters.
PB constant orifice nominal pressure drop — Nominal pressure drop
0.001
MPa
(default)  positive scalar
Typical, rated, or design pressure drop through a constant PB orifice.
Dependencies
To enable this parameter, set:
Modeling option to
Liquid operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Linear  Nominal mass flow rate vs. spool travel
One of the following settings in each parameter:
Positive spool position open connections to:
PB, AT
PA, PB
PB
PA, PB, AT, BT
Negative spool position open connections to:
PB, AT
PA, PB
PB
PA, PB, AT, BT
Note:
This parameter is enabled only when the PB orifice settings appear in both the Positive spool position open connections and Negative spool position open connections parameters.
PB constant orifice Cv flow coefficient — Flow coefficient
4
(default)  positive scalar
Value of the constant C_{v} flow coefficient for the PB orifice. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential.
Dependencies
To enable this parameter, set:
Modeling option to
Vapor operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Cv flow coefficient
One of the following settings in each parameter:
Positive spool position open connections to:
PB, AT
PA, PB
PB
PA, PB, AT, BT
Negative spool position open connections to:
PB, AT
PA, PB
PB
PA, PB, AT, BT
Note:
This parameter is enabled only when the PB orifice settings appear in both the Positive spool position open connections and Negative spool position open connections parameters.
PB orifice maximum Cv flow coefficient — C_{v} coefficient that corresponds to maximally open component
4
(default)  positive scalar
Value of the C_{v} flow coefficient when the PB orifice is fully open and the area available for flow is at a maximum. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential.
Dependencies
To enable this parameter, set:
Modeling option to
Vapor operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Cv flow coefficient
Opening characteristic to
Linear
One of the following parameters:
Positive spool position open connections to:
PB, AT
PA, PB
PB
PA, PB, AT, BT
Negative spool position open connections to:
PB, AT
PA, PB
PB
PA, PB, AT, BT
PB orifice Cv flow coefficient vector — C_{v} coefficients for values in member position vector
[1e06, .8, 1.6, 2.4, 3.2, 4]
(default)  1byn vector
Vector of C_{v} flow coefficients. Each coefficient corresponds to a value in the PB orifice spool travel vector parameter. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential. The size of the vector must be the same as the PB orifice spool travel vector parameter.
Dependencies
To enable this parameter, set:
Modeling option to
Vapor operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Cv flow coefficient
Opening characteristic to
Tabulated
One of the following parameters:
Positive spool position open connections to:
PB, AT
PA, PB
PB
PA, PB, AT, BT
Negative spool position open connections to:
PB, AT
PA, PB
PB
PA, PB, AT, BT
PB constant orifice Kv flow coefficient — Flow coefficient
3.6
(default)  positive scalar
Value of the constant K_{v} flow coefficient for the PB orifice. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential.
Dependencies
To enable this parameter, set:
Modeling option to
Vapor operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Kv flow coefficient
One of the following settings in each parameter:
Positive spool position open connections to:
PB, AT
PA, PB
PB
PA, PB, AT, BT
Negative spool position open connections to:
PB, AT
PA, PB
PB
PA, PB, AT, BT
Note:
This parameter is enabled only when the PB orifice settings appear in both the Positive spool position open connections and Negative spool position open connections parameters.
PB orifice maximum Kv flow coefficient — K_{v} coefficient that corresponds to maximally open component
3.6
(default)  positive scalar
Value of the K_{v} flow coefficient when the PB orifice is fully open and the area available for flow is at a maximum. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential.
Dependencies
To enable this parameter, set:
Modeling option to
Vapor operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Kv flow coefficient
Opening characteristic to
Linear
One of the following parameters:
Positive spool position open connections to:
PB, AT
PA, PB
PB
PA, PB, AT, BT
Negative spool position open connections to:
PB, AT
PA, PB
PB
PA, PB, AT, BT
PB orifice Kv flow coefficient vector — K_{v} coefficients for values in member position vector
[1e06, .72, 1.44, 2.16, 2.88, 3.6]
(default)  1byn vector
Vector of K_{v} flow coefficients. Each coefficient corresponds to a value in the PB orifice spool travel vector parameter. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential. The size of the vector must be the same as the PB orifice spool travel vector parameter.
Dependencies
To enable this parameter, set:
Modeling option to
Vapor operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Kv flow coefficient
Opening characteristic to
Tabulated
One of the following parameters:
Positive spool position open connections to:
PB, AT
PA, PB
PB
PA, PB, AT, BT
Negative spool position open connections to:
PB, AT
PA, PB
PB
PA, PB, AT, BT
PB orifice spool travel vector — Vector of spool opening distances relative to fully closed position
[0, .00125, .0025, .00375, .005]
m
(default)  1byn vector
Vector of spool travel distances for the tabular parameterization of the valve area. List the values in ascending order. The first element must be 0. The block uses linear interpolation between table data points.
Dependencies
To enable this parameter, set one of the following parameters:
Positive spool position open connections to:
PB, AT
PA, PB
PB
PA, PB, AT, BT
Negative spool position open connections to:
PB, AT
PA, PB
PB
PA, PB, AT, BT
And either:
Modeling option to
Liquid operating condition
, Area characteristics toDifferent for each flow path
, and Orifice parameterization toTabulated data  Area vs. spool travel
.Modeling option to
Vapor operating condition
, Area characteristics toDifferent for each flow path
, and Opening characteristic toTabulated
.
PB maximum orifice area — Maximum orifice opening area
1e4 m^2
(default)  positive scalar
Largest open area of the PB orifice during the operation of the valve.
Dependencies
To enable this parameter, set one of the following parameters:
Positive spool position open connections to:
PB, AT
PA, PB
PB
PA, PB, AT, BT
Negative spool position open connections to:
PB, AT
PA, PB
PB
PA, PB, AT, BT
Also set Area characteristics to
Different for each flow path
and
either:
Modeling option to
Liquid operating condition
and Orifice parameterization toLinear  Area vs. spool travel
.Modeling option to
Vapor operating condition
, Orifice parameterization toOrifice area
, and Opening characteristic toLinear
.
PB orifice area vector — Vector of valve opening areas
[1e10, 1e05, 4e05, 6e05, .0001]
m^2
(default)  1byn vector
Vector of opening areas for the tabular parameterization of the valve area. The vector elements must correspond onetoone with the elements in the PB orifice spool travel vector parameter. The elements must be greater than 0 and listed in ascending order.
Dependencies
To enable this parameter, set one of the following parameters:
Positive spool position open connections to:
PB, AT
PA, PB
PB
PA, PB, AT, BT
Negative spool position open connections to:
PB, AT
PA, PB
PB
PA, PB, AT, BT
Also set Area characteristics to
Different for each flow path
and
either:
Modeling option to
Liquid operating condition
and Orifice parameterization toTabulated data  Area vs. spool travel
.Modeling option to
Vapor operating condition
, Orifice parameterization toOrifice area
, and Opening characteristic toTabulated
.
PB constant orifice area — Crosssectional area for constant orifice
1e4 m^2
(default)  positive scalar
Orifice area when the positive and negative spool positions include the same orifice.
Dependencies
To enable this parameter, set one of the following settings in each parameter:
Positive spool position open connections to:
PB, AT
PA, PB
PB
PA, PB, AT, BT
Negative spool position open connections to:
PB, AT
PA, PB
PB
PA, PB, AT, BT
And either:
Modeling option to
Liquid operating condition
, Area characteristics toDifferent for each flow path
, and Orifice parameterization toTabulated data  Area vs. spool travel
orLinear  Area vs. spool travel
.Modeling option to
Vapor operating condition
, Area characteristics toDifferent for each flow path
, and Opening characteristic toTabulated
.
Note:
This parameter is enabled only when the PB orifice settings appear in both the Positive spool position open connections and Negative spool position open connections parameters.
PB orifice xT pressure differential ratio factor at choked flow — Ratio of pressure differentials
0.7
(default)  positive scalar
Ratio between the inlet pressure, p_{in}, and the outlet pressure, p_{out}, defined as $$({p}_{in}{p}_{out})/{p}_{in}$$ where choking first occurs for the PB orifice.
Dependencies
To enable this parameter, set:
Modeling option to
Vapor operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Kv flow coefficient
orCv flow coefficient
At least one of the following parameters:
Positive spool position open connections to:
PB, AT
PA, PB
PB
PA, PB, AT, BT
Negative spool position open connections to:
PB, AT
PA, PB
PB
PA, PB, AT, BT
AT Orifice
Spool position at maximum AT orifice area — Spool offset for fully open AT orifice
5e3 m
(default)  positive scalar
Spool offset from the neutral position for a fully open AT orifice.
Dependencies
To enable this parameter, set one of these parameters.
Positive spool position open connections to
PB, AT
orPA, PB, AT, BT
.Negative spool position open connections to
PB, AT
orPA, PB, AT, BT
.
Note:
This parameter is enabled only when the AT orifice settings do not appear in both the Positive spool position open connections and Negative spool position open connections parameters.
AT spool travel between closed and open orifice — Maximum spool stroke
0.005 m
(default)  positive scalar
Maximum distance of spool travel. This value provides an upper limit to calculations so that simulations do not return unphysical values.
Dependencies
To enable this parameter, set one of the following parameters:
Positive spool position open connections to
PB, AT
orPA, PB, AT, BT
.Negative spool position open connections to
PB, AT
orPA, PB, AT, BT
.
And either:
Modeling option to
Liquid operating condition
, Area characteristics toDifferent for each flow path
, and Orifice parameterization toLinear  Area vs. spool travel
orLinear  Nominal mass flow rate vs. spool travel
.Modeling option to
Vapor operating condition
, Area characteristics toDifferent for each flow path
, and Opening characteristic toLinear
.
AT nominal mass flow rate at maximum orifice opening — Rated mass flow rate
0.1
kg/s
(default)  positive scalar
Typical, rated, or design mass flow rate through a maximally open AT orifice.
Dependencies
To enable this parameter, set:
Modeling option to
Liquid operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Linear  Nominal mass flow rate vs. spool travel
One of the following parameters:
Positive spool position open connections to
PB, AT
orPA, PB, AT, BT
.Negative spool position open connections to
PB, AT
orPA, PB, AT, BT
.
AT nominal pressure drop at maximum orifice opening — Rated pressure drop
0.001
MPa
(default)  positive scalar
Typical, rated, or design pressure drop through a maximally open AT orifice.
Dependencies
To enable this parameter, set:
Modeling option to
Liquid operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Linear  Nominal mass flow rate vs. spool travel
One of the following parameters:
Positive spool position open connections to
PB, AT
orPA, PB, AT, BT
.Negative spool position open connections to
PB, AT
orPA, PB, AT, BT
.
AT nominal inlet condition specification — Method of determining inlet fluid state
Temperature
(default)  Vapor quality
 Vapor void fraction
 Specific enthalpy
 Specific internal energy
Method of determining the inlet fluid state for AT orifice.
Dependencies
To enable this parameter, set:
Modeling option to
Liquid operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Linear  Nominal mass flow rate vs. spool travel
At least one of the following parameters:
Positive spool position open connections to
PB, AT
orPA, PB, AT, BT
.Negative spool position open connections to
PB, AT
orPA, PB, AT, BT
.
AT nominal inlet pressure — Inlet fluid pressure
0.101325
MPa
(default)  positive scalar
Inlet pressure for the AT orifice at nominal conditions.
Dependencies
To enable this parameter, set:
Modeling option to
Liquid operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Linear  Nominal mass flow rate vs. spool travel
At least one of the following parameters:
Positive spool position open connections to
PB, AT
orPA, PB, AT, BT
.Negative spool position open connections to
PB, AT
orPA, PB, AT, BT
.
AT nominal inlet temperature — Fluid temperature
293.15
K
(default)  positive scalar
Inlet fluid temperature for the AT orifice in nominal operating conditions.
Dependencies
To enable this parameter, set:
Modeling option to
Liquid operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Linear  Nominal mass flow rate vs. spool travel
Nominal inlet condition specification to
Temperature
At least one of the following parameters:
Positive spool position open connections to
PB, AT
orPA, PB, AT, BT
.Negative spool position open connections to
PB, AT
orPA, PB, AT, BT
.
AT nominal inlet vapor quality — Inlet vapor quality mass fraction
0
(default)  positive scalar in the range [0,1]
Inlet mixture vapor quality by mass fraction for the AT orifice in nominal operating
conditions. A value of 0
means that the inlet fluid
is subcooled liquid. A value of 1
means that the
inlet fluid is superheated vapor.
Dependencies
To enable this parameter, set:
Modeling option to
Liquid operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Linear  Nominal mass flow rate vs. spool travel
Nominal inlet condition specification to
Vapor quality
At least one of the following parameters:
Positive spool position open connections to
PB, AT
orPA, PB, AT, BT
.Negative spool position open connections to
PB, AT
orPA, PB, AT, BT
.
AT nominal inlet vapor void fraction — Inlet vapor void fraction
0
(default)  positive scalar in the range [0,1]
Inlet mixture vapor void fraction for the AT orifice in nominal operating conditions. A
value of 0
means that the inlet fluid is subcooled
liquid. A value of 1
means that the inlet fluid is
superheated vapor.
Dependencies
To enable this parameter, set:
Modeling option to
Liquid operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Linear  Nominal mass flow rate vs. spool travel
Nominal inlet condition specification to
Vapor void fraction
At least one of the following parameters:
Positive spool position open connections to
PB, AT
orPA, PB, AT, BT
.Negative spool position open connections to
PB, AT
orPA, PB, AT, BT
.
AT nominal inlet specific enthalpy — Inlet fluid specific enthalpy
400
kJ/kg
(default)  positive scalar
Inlet specific enthalpy for the AT orifice in nominal operating conditions.
Dependencies
To enable this parameter, set:
Modeling option to
Liquid operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Linear  Nominal mass flow rate vs. spool travel
Nominal inlet condition specification to
Specific enthalpy
At least one of the following parameters:
Positive spool position open connections to
PB, AT
orPA, PB, AT, BT
.Negative spool position open connections to
PB, AT
orPA, PB, AT, BT
.
AT nominal inlet specific internal energy — Inlet specific internal energy
400
kJ/kg
(default)  positive scalar
Inlet specific internal energy for the AT orifice in nominal operating conditions.
Dependencies
To enable this parameter, set:
Modeling option to
Liquid operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Linear  Nominal mass flow rate vs. spool travel
Nominal inlet condition specification to
Specific internal energy
At least one of the following parameters:
Positive spool position open connections to
PB, AT
orPA, PB, AT, BT
.Negative spool position open connections to
PB, AT
orPA, PB, AT, BT
.
AT constant orifice nominal mass flow rate — Nominal mass flow rate
0.1
kg/s
(default)  positive scalar
Typical, rated, or design mass flow rate through a constant AT orifice.
Dependencies
To enable this parameter, set:
Modeling option to
Liquid operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Linear  Nominal mass flow rate vs. spool travel
One of the following settings in each parameter:
Positive spool position open connections to
PB, AT
orPA, PB, AT, BT
.Negative spool position open connections to
PB, AT
orPA, PB, AT, BT
.
Note:
This parameter is enabled only when the AT orifice settings appear in both the Positive spool position open connections and Negative spool position open connections parameters.
AT constant orifice nominal pressure drop — Nominal pressure drop
0.001
MPa
(default)  positive scalar
Typical, rated, or design pressure drop through a constant AT orifice.
Dependencies
To enable this parameter, set:
Modeling option to
Liquid operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Linear  Nominal mass flow rate vs. spool travel
One of the following settings in each parameter:
Positive spool position open connections to
PB, AT
orPA, PB, AT, BT
.Negative spool position open connections to
PB, AT
orPA, PB, AT, BT
.
Note:
This parameter is enabled only when the AT orifice settings appear in both the Positive spool position open connections and Negative spool position open connections parameters.
AT constant orifice Cv flow coefficient — Flow coefficient
4
(default)  positive scalar
Value of the constant C_{v} flow coefficient for the AT orifice. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential.
Dependencies
To enable this parameter, set:
Modeling option to
Vapor operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Cv flow coefficient
One of the following settings in each parameter:
Positive spool position open connections to
PB, AT
orPA, PB, AT, BT
.Negative spool position open connections to
PB, AT
orPA, PB, AT, BT
.
Note:
This parameter is enabled only when the AT orifice settings appear in both the Positive spool position open connections and Negative spool position open connections parameters.
AT orifice maximum Cv flow coefficient — C_{v} coefficient that corresponds to maximally open component
4
(default)  positive scalar
Value of the C_{v} flow coefficient when the AT orifice is fully open and the area available for flow is at a maximum. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential.
Dependencies
To enable this parameter, set:
Modeling option to
Vapor operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Cv flow coefficient
Opening characteristic to
Linear
One of the following parameters:
Positive spool position open connections to
PB, AT
orPA, PB, AT, BT
.Negative spool position open connections to
PB, AT
orPA, PB, AT, BT
.
AT orifice Cv flow coefficient vector — C_{v} coefficients for values in member position vector
[1e06, .8, 1.6, 2.4, 3.2, 4]
(default)  1byn vector
Vector of C_{v} flow coefficients. Each coefficient corresponds to a value in the AT orifice spool travel vector parameter. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential. The size of the vector must be the same as the AT orifice spool travel vector parameter.
Dependencies
To enable this parameter, set:
Modeling option to
Vapor operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Cv flow coefficient
Opening characteristic to
Tabulated
One of the following parameters:
Positive spool position open connections to
PB, AT
orPA, PB, AT, BT
.Negative spool position open connections to
PB, AT
orPA, PB, AT, BT
.
AT constant orifice Kv flow coefficient — Flow coefficient
3.6
(default)  positive scalar
Value of the constant K_{v} flow coefficient for the AT orifice. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential.
Dependencies
To enable this parameter, set:
Modeling option to
Vapor operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Kv flow coefficient
One of the following settings in each parameter:
Positive spool position open connections to
PB, AT
orPA, PB, AT, BT
.Negative spool position open connections to
PB, AT
orPA, PB, AT, BT
.
Note:
This parameter is enabled only when the AT orifice settings appear in both the Positive spool position open connections and Negative spool position open connections parameters.
AT orifice maximum Kv flow coefficient — K_{v} coefficient that corresponds to maximally open component
3.6
(default)  positive scalar
Value of the K_{v} flow coefficient when the AT orifice is fully open and the area available for flow is at a maximum. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential.
Dependencies
To enable this parameter, set:
Modeling option to
Vapor operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Kv flow coefficient
Opening characteristic to
Linear
One of the following parameters:
Positive spool position open connections to
PB, AT
orPA, PB, AT, BT
.Negative spool position open connections to
PB, AT
orPA, PB, AT, BT
.
AT orifice Kv flow coefficient vector — K_{v} coefficients for values in member position vector
[1e06, .72, 1.44, 2.16, 2.88, 3.6]
(default)  1byn vector
Vector of K_{v} flow coefficients. Each coefficient corresponds to a value in the AT orifice spool travel vector parameter. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential. The size of the vector must be the same as the AT orifice spool travel vector parameter.
Dependencies
To enable this parameter, set:
Modeling option to
Vapor operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Kv flow coefficient
Opening characteristic to
Tabulated
One of the following parameters:
Positive spool position open connections to
PB, AT
orPA, PB, AT, BT
.Negative spool position open connections to
PB, AT
orPA, PB, AT, BT
.
AT orifice spool travel vector — Vector of spool opening distances relative to fully closed position
[0, .00125, .0025, .00375, .005]
m
(default)  1byn vector
Vector of spool travel distances for the tabular parameterization of the valve area. List the values in ascending order. The first element must be 0. The block uses linear interpolation between table data points.
Dependencies
To enable this parameter, set one of the following parameters:
Positive spool position open connections to
PB, AT
orPA, PB, AT, BT
.Negative spool position open connections to
PB, AT
orPA, PB, AT, BT
.
And either:
Modeling option to
Liquid operating condition
, Area characteristics toDifferent for each flow path
, and Orifice parameterization toTabulated data  Area vs. spool travel
.Modeling option to
Vapor operating condition
, Area characteristics toDifferent for each flow path
, and Opening characteristic toTabulated
.
AT maximum orifice area — Maximum orifice opening area
1e4 m^2
(default)  positive scalar
Largest open area of the AT orifice during the operation of the valve.
Dependencies
To enable this parameter, set one of the following parameters:
Positive spool position open connections to
PB, AT
orPA, PB, AT, BT
.Negative spool position open connections to
PB, AT
orPA, PB, AT, BT
.
Also set Area characteristics to
Different for each flow path
and
either:
Modeling option to
Liquid operating condition
and Orifice parameterization toLinear  Area vs. spool travel
.Modeling option to
Vapor operating condition
, Orifice parameterization toOrifice area
, and Opening characteristic toLinear
.
AT orifice area vector — Vector of valve opening areas
[1e10, 1e05, 4e05, 6e05, .0001]
m^2
(default)  1byn vector
Vector of opening areas for the tabular parameterization of the valve area. The vector elements must correspond onetoone with the elements in the AT orifice spool travel vector parameter. The elements must be greater than 0 and listed in ascending order.
Dependencies
To enable this parameter, set one of the following parameters:
Positive spool position open connections to
PB, AT
orPA, PB, AT, BT
.Negative spool position open connections to
PB, AT
orPA, PB, AT, BT
.
Also set Area characteristics to
Different for each flow path
and
either:
Modeling option to
Liquid operating condition
and Orifice parameterization toTabulated data  Area vs. spool travel
.Modeling option to
Vapor operating condition
, Orifice parameterization toOrifice area
, and Opening characteristic toTabulated
.
AT constant orifice area — Crosssectional area for constant orifice
1e4 m^2
(default)  positive scalar
Orifice area when the positive and negative spool positions include the same orifice.
Dependencies
To enable this parameter, set one of the following settings in each parameter:
Positive spool position open connections to
PB, AT
orPA, PB, AT, BT
.Negative spool position open connections to
PB, AT
orPA, PB, AT, BT
.
And either:
Modeling option to
Liquid operating condition
, Area characteristics toDifferent for each flow path
, and Orifice parameterization toTabulated data  Area vs. spool travel
orLinear  Area vs. spool travel
.Modeling option to
Vapor operating condition
, Area characteristics toDifferent for each flow path
, and Opening characteristic toTabulated
.
Note:
This parameter is enabled only when the AT orifice settings appear in both the Positive spool position open connections and Negative spool position open connections parameters.
AT orifice xT pressure differential ratio factor at choked flow — Ratio of pressure differentials
0.7
(default)  positive scalar
Ratio between the inlet pressure, p_{in}, and the outlet pressure, p_{out}, defined as $$({p}_{in}{p}_{out})/{p}_{in}$$ where choking first occurs for the AT orifice.
Dependencies
To enable this parameter, set:
Modeling option to
Vapor operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Kv flow coefficient
orCv flow coefficient
At least one of the following parameters:
Positive spool position open connections to
PB, AT
orPA, PB, AT, BT
.Negative spool position open connections to
PB, AT
orPA, PB, AT, BT
.
BT Orifice
Spool position at maximum BT orifice area — Spool offset for fully open BT orifice
5e3 m
(default)  positive scalar
Spool offset from the neutral position for a fully open BT orifice.
Dependencies
To enable this parameter, set one of these parameters.
Positive spool position open connections to
PA, BT
orPA, PB, AT, BT
.Negative spool position open connections to
PA, BT
orPA, PB, AT, BT
.
Note:
This parameter is enabled only when the BT orifice settings do not appear in both the Positive spool position open connections and Negative spool position open connections parameters.
BT spool travel between closed and open orifice — Maximum spool stroke
0.005 m
(default)  positive scalar
Maximum distance of spool travel. This value provides an upper limit to calculations so that simulations do not return unphysical values.
Dependencies
To enable this parameter, set one of the following parameters:
Positive spool position open connections to
PA, BT
orPA, PB, AT, BT
.Negative spool position open connections to
PA, BT
orPA, PB, AT, BT
.
And either:
Modeling option to
Liquid operating condition
, Area characteristics toDifferent for each flow path
, and Orifice parameterization toLinear  Area vs. spool travel
orLinear  Nominal mass flow rate vs. spool travel
.Modeling option to
Vapor operating condition
, Area characteristics toDifferent for each flow path
, and Opening characteristic toLinear
.
BT nominal mass flow rate at maximum orifice opening — Rated mass flow rate
0.1
kg/s
(default)  positive scalar
Typical, rated, or design mass flow rate through a maximally open BT orifice.
Dependencies
To enable this parameter, set:
Modeling option to
Liquid operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Linear  Nominal mass flow rate vs. spool travel
One of the following parameters:
Positive spool position open connections to
PA, BT
orPA, PB, AT, BT
.Negative spool position open connections to
PA, BT
orPA, PB, AT, BT
.
BT nominal pressure drop at maximum orifice opening — Rated pressure drop
0.001
MPa
(default)  positive scalar
Typical, rated, or design pressure drop through a maximally open BT orifice.
Dependencies
To enable this parameter, set:
Modeling option to
Liquid operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Linear  Nominal mass flow rate vs. spool travel
One of the following parameters:
Positive spool position open connections to
PA, BT
orPA, PB, AT, BT
.Negative spool position open connections to
PA, BT
orPA, PB, AT, BT
.
BT nominal inlet condition specification — Method of determining inlet fluid state
Temperature
(default)  Vapor quality
 Vapor void fraction
 Specific enthalpy
 Specific internal energy
Method of determining the inlet fluid state for BT orifice.
Dependencies
To enable this parameter, set:
Modeling option to
Liquid operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Linear  Nominal mass flow rate vs. spool travel
At least one of the following parameters:
Positive spool position open connections to
PA, BT
orPA, PB, AT, BT
.Negative spool position open connections to
PA, BT
orPA, PB, AT, BT
.
BT nominal inlet pressure — Inlet fluid pressure
0.101325
MPa
(default)  positive scalar
Inlet pressure for the BT orifice at nominal conditions.
Dependencies
To enable this parameter, set:
Modeling option to
Liquid operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Linear  Nominal mass flow rate vs. spool travel
At least one of the following parameters:
Positive spool position open connections to
PA, BT
orPA, PB, AT, BT
.Negative spool position open connections to
PA, BT
orPA, PB, AT, BT
.
BT nominal inlet temperature — Fluid temperature
293.15
K
(default)  positive scalar
Inlet fluid temperature for the BT orifice in nominal operating conditions.
Dependencies
To enable this parameter, set:
Modeling option to
Liquid operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Linear  Nominal mass flow rate vs. spool travel
Nominal inlet condition specification to
Temperature
At least one of the following parameters:
Positive spool position open connections to
PA, BT
orPA, PB, AT, BT
.Negative spool position open connections to
PA, BT
orPA, PB, AT, BT
.
BT nominal inlet vapor quality — Inlet vapor quality mass fraction
0
(default)  positive scalar in the range [0,1]
Inlet mixture vapor quality by mass fraction for the BT orifice in nominal operating
conditions. A value of 0
means that the inlet fluid
is subcooled liquid. A value of 1
means that the
inlet fluid is superheated vapor.
Dependencies
To enable this parameter, set:
Modeling option to
Liquid operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Linear  Nominal mass flow rate vs. spool travel
Nominal inlet condition specification to
Vapor quality
At least one of the following parameters:
Positive spool position open connections to
PA, BT
orPA, PB, AT, BT
.Negative spool position open connections to
PA, BT
orPA, PB, AT, BT
.
BT nominal inlet vapor void fraction — Inlet vapor void fraction
0
(default)  positive scalar in the range [0,1]
Inlet mixture vapor void fraction for the BT orifice in nominal operating conditions. A
value of 0
means that the inlet fluid is subcooled
liquid. A value of 1
means that the inlet fluid is
superheated vapor.
Dependencies
To enable this parameter, set:
Modeling option to
Liquid operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Linear  Nominal mass flow rate vs. spool travel
Nominal inlet condition specification to
Vapor void fraction
At least one of the following parameters:
Positive spool position open connections to
PA, BT
orPA, PB, AT, BT
.Negative spool position open connections to
PA, BT
orPA, PB, AT, BT
.
BT nominal inlet specific enthalpy — Inlet fluid specific enthalpy
400
kJ/kg
(default)  positive scalar
Inlet specific enthalpy for the BT orifice in nominal operating conditions.
Dependencies
To enable this parameter, set:
Modeling option to
Liquid operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Linear  Nominal mass flow rate vs. spool travel
Nominal inlet condition specification to
Specific enthalpy
At least one of the following parameters:
Positive spool position open connections to
PA, BT
orPA, PB, AT, BT
.Negative spool position open connections to
PA, BT
orPA, PB, AT, BT
.
BT nominal inlet specific internal energy — Inlet specific internal energy
400
kJ/kg
(default)  positive scalar
Inlet specific internal energy for the BT orifice in nominal operating conditions.
Dependencies
To enable this parameter, set:
Modeling option to
Liquid operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Linear  Nominal mass flow rate vs. spool travel
Nominal inlet condition specification to
Specific internal energy
At least one of the following parameters:
Positive spool position open connections to
PA, BT
orPA, PB, AT, BT
.Negative spool position open connections to
PA, BT
orPA, PB, AT, BT
.
BT constant orifice nominal mass flow rate — Nominal mass flow rate
0.1
kg/s
(default)  positive scalar
Typical, rated, or design mass flow rate through a constant BT orifice.
Dependencies
To enable this parameter, set:
Modeling option to
Liquid operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Linear  Nominal mass flow rate vs. spool travel
One of the following settings in each parameter:
Positive spool position open connections to
PA, BT
orPA, PB, AT, BT
.Negative spool position open connections to
PA, BT
orPA, PB, AT, BT
.
Note:
This parameter is enabled only when the BT orifice settings appear in both the Positive spool position open connections and Negative spool position open connections parameters.
BT constant orifice nominal pressure drop — Nominal pressure drop
0.001
MPa
(default)  positive scalar
Typical, rated, or design pressure drop through a constant BT orifice.
Dependencies
To enable this parameter, set:
Modeling option to
Liquid operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Linear  Nominal mass flow rate vs. spool travel
One of the following settings in each parameter:
Positive spool position open connections to
PA, BT
orPA, PB, AT, BT
.Negative spool position open connections to
PA, BT
orPA, PB, AT, BT
.
Note:
This parameter is enabled only when the BT orifice settings appear in both the Positive spool position open connections and Negative spool position open connections parameters.
BT constant orifice Cv flow coefficient — Flow coefficient
4
(default)  positive scalar
Value of the constant C_{v} flow coefficient for the BT orifice. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential.
Dependencies
To enable this parameter, set:
Modeling option to
Vapor operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Cv flow coefficient
One of the following settings in each parameter:
Positive spool position open connections to
PA, BT
orPA, PB, AT, BT
.Negative spool position open connections to
PA, BT
orPA, PB, AT, BT
.
Note:
This parameter is enabled only when the BT orifice settings appear in both the Positive spool position open connections and Negative spool position open connections parameters.
BT orifice maximum Cv flow coefficient — C_{v} coefficient that corresponds to maximally open component
4
(default)  positive scalar
Value of the C_{v} flow coefficient when the BT orifice is fully open and the area available for flow is at a maximum. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential.
Dependencies
To enable this parameter, set:
Modeling option to
Vapor operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Cv flow coefficient
Opening characteristic to
Linear
One of the following parameters:
Positive spool position open connections to
PA, BT
orPA, PB, AT, BT
.Negative spool position open connections to
PA, BT
orPA, PB, AT, BT
.
BT orifice Cv flow coefficient vector — C_{v} coefficients for values in member position vector
[1e06, .8, 1.6, 2.4, 3.2, 4]
(default)  1byn vector
Vector of C_{v} flow coefficients. Each coefficient corresponds to a value in the BT orifice spool travel vector parameter. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential. The size of the vector must be the same as the BT orifice spool travel vector parameter.
Dependencies
To enable this parameter, set:
Modeling option to
Vapor operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Cv flow coefficient
Opening characteristic to
Tabulated
One of the following parameters:
Positive spool position open connections to
PA, BT
orPA, PB, AT, BT
.Negative spool position open connections to
PA, BT
orPA, PB, AT, BT
.
BT constant orifice Kv flow coefficient — Flow coefficient
3.6
(default)  positive scalar
Value of the constant K_{v} flow coefficient for the BT orifice. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential.
Dependencies
To enable this parameter, set:
Modeling option to
Vapor operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Kv flow coefficient
One of the following settings in each parameter:
Positive spool position open connections to
PA, BT
orPA, PB, AT, BT
.Negative spool position open connections to
PA, BT
orPA, PB, AT, BT
.
Note:
This parameter is enabled only when the BT orifice settings appear in both the Positive spool position open connections and Negative spool position open connections parameters.
BT orifice maximum Kv flow coefficient — K_{v} coefficient that corresponds to maximally open component
3.6
(default)  positive scalar
Value of the K_{v} flow coefficient when the BT orifice is fully open and the area available for flow is at a maximum. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential.
Dependencies
To enable this parameter, set:
Modeling option to
Vapor operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Kv flow coefficient
Opening characteristic to
Linear
One of the following parameters:
Positive spool position open connections to
PA, BT
orPA, PB, AT, BT
.Negative spool position open connections to
PA, BT
orPA, PB, AT, BT
.
BT orifice Kv flow coefficient vector — K_{v} coefficients for values in member position vector
[1e06, .72, 1.44, 2.16, 2.88, 3.6]
(default)  1byn vector
Vector of K_{v} flow coefficients. Each coefficient corresponds to a value in the BT orifice spool travel vector parameter. This parameter measures the ease with which the vapor traverses the resistive element when driven by a pressure differential. The size of the vector must be the same as the BT orifice spool travel vector parameter.
Dependencies
To enable this parameter, set:
Modeling option to
Vapor operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Kv flow coefficient
Opening characteristic to
Tabulated
One of the following parameters:
Positive spool position open connections to
PA, BT
orPA, PB, AT, BT
.Negative spool position open connections to
PA, BT
orPA, PB, AT, BT
.
BT orifice spool travel vector — Vector of spool opening distances relative to fully closed position
[0, .00125, .0025, .00375, .005]
m
(default)  1byn vector
Vector of spool travel distances for the tabular parameterization of the valve area. List the values in ascending order. The first element must be 0. The block uses linear interpolation between table data points.
Dependencies
To enable this parameter, set one of the following parameters:
Positive spool position open connections to
PA, BT
orPA, PB, AT, BT
.Negative spool position open connections to
PA, BT
orPA, PB, AT, BT
.
And either:
Modeling option to
Liquid operating condition
, Area characteristics toDifferent for each flow path
, and Orifice parameterization toTabulated data  Area vs. spool travel
.Modeling option to
Vapor operating condition
, Area characteristics toDifferent for each flow path
, and Opening characteristic toTabulated
.
BT maximum orifice area — Maximum orifice opening area
1e4 m^2
(default)  positive scalar
Largest open area of the BT orifice during the operation of the valve.
Dependencies
To enable this parameter, set one of the following parameters:
Positive spool position open connections to
PA, BT
orPA, PB, AT, BT
.Negative spool position open connections to
PA, BT
orPA, PB, AT, BT
.
Also set Area characteristics to
Different for each flow path
and
either:
Modeling option to
Liquid operating condition
and Orifice parameterization toLinear  Area vs. spool travel
.Modeling option to
Vapor operating condition
, Orifice parameterization toOrifice area
, and Opening characteristic toLinear
.
BT orifice area vector — Vector of valve opening areas
[1e10, 1e05, 4e05, 6e05, .0001]
m^2
(default)  1byn vector
Vector of opening areas for the tabular parameterization of the valve area. The vector elements must correspond onetoone with the elements in the BT orifice spool travel vector parameter. The elements must be greater than 0 and listed in ascending order.
Dependencies
To enable this parameter, set one of the following parameters:
Positive spool position open connections to
PA, BT
orPA, PB, AT, BT
.Negative spool position open connections to
PA, BT
orPA, PB, AT, BT
.
Also set Area characteristics to
Different for each flow path
and
either:
Modeling option to
Liquid operating condition
and Orifice parameterization toTabulated data  Area vs. spool travel
.Modeling option to
Vapor operating condition
, Orifice parameterization toOrifice area
, and Opening characteristic toTabulated
.
BT constant orifice area — Crosssectional area for constant orifice
1e4 m^2
(default)  positive scalar
Orifice area when the positive and negative spool positions include the same orifice.
Dependencies
To enable this parameter, set one of the following settings in each parameter:
Positive spool position open connections to
PA, BT
orPA, PB, AT, BT
.Negative spool position open connections to
PA, BT
orPA, PB, AT, BT
.
And either:
Modeling option to
Liquid operating condition
, Area characteristics toDifferent for each flow path
, and Orifice parameterization toTabulated data  Area vs. spool travel
orLinear  Area vs. spool travel
.Modeling option to
Vapor operating condition
, Area characteristics toDifferent for each flow path
, and Opening characteristic toTabulated
.
Note:
This parameter is enabled only when the BT orifice settings appear in both the Positive spool position open connections and Negative spool position open connections parameters.
BT orifice xT pressure differential ratio factor at choked flow — Ratio of pressure differentials
0.7
(default)  positive scalar
Ratio between the inlet pressure, p_{in}, and the outlet pressure, p_{out}, defined as $$({p}_{in}{p}_{out})/{p}_{in}$$ where choking first occurs for the BT orifice.
Dependencies
To enable this parameter, set:
Modeling option to
Vapor operating condition
Area characteristics to
Different for each flow path
Orifice parameterization to
Kv flow coefficient
orCv flow coefficient
At least one of the following parameters:
Positive spool position open connections to
PA, BT
orPA, PB, AT, BT
.Negative spool position open connections to
PA, BT
orPA, PB, AT, BT
.
Extended Capabilities
C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.
Version History
Introduced in R2024b
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