Butterfly Valve (MA)

R2026b

Butterfly valve in a moist air network

Since R2026b

Libraries:
Simscape / Fluids / Moist Air / Valves & Orifices / Flow Control Valves

Description

The Butterfly Valve (MA) block models flow through a butterfly valve in a moist air network. A rotating disc inside the valve body controls the flow. When the disc aligns with the flow path, the valve is open. When the disc is perpendicular to the flow path, the valve is closed. The physical signal at port S controls the disc rotation angle.

Valve Parameterizations

The block behavior depends on the Valve parametrization parameter:

Cv flow coefficient — The flow coefficient C_v determines the block parameterization. The flow coefficient measures the ease with which the moist air flows when driven by a certain pressure differential.
Kv flow coefficient — The flow coefficient K_v, where $K_{v} = 0.865 C_{v}$ , determines the block parameterization. The flow coefficient measures the ease with which the moist air flows when driven by a certain pressure differential.
Sonic conductance — The sonic conductance of the resistive element at steady state determines the block parameterization. The sonic conductance measures the ease with which the moist air flows when choked, which is a condition in which the flow velocity is at the local speed of sound. Choking occurs when the ratio between downstream and upstream pressures reaches a critical value known as the critical pressure ratio.
Orifice area — The size of the flow restriction determines the block parametrization.

Opening Area

The block calculates the valve opening area during simulation by using the input at port S. The opening area calculations depend on the Opening Characteristic parameter.

Area of Projected Ellipses

If you set Opening Characteristic to Area of projected ellipses, the block calculates the flow area as the area of a circle minus the obstruction from the disc. When the disc rotates, it creates an elliptical obstruction. The physical signal at port S controls the disc rotation. The valve is fully shut when the signal at port S is 0. If the value of the Disc thickness parameter is zero, the valve is fully open when the signal at port S is π/2 rad. Otherwise, the valve is fully open when the signal at port S is a value less than π/2 rad. This value depends on the value of the Disc thickness parameter.

The opening area is

$A = α (1 - \cos (φ)),$

where:

α is the value of the Disc area parameter.
φ is the rotation of the disc, specified by the physical signal at port S.

The block normalizes the opening area by the valve maximum area,

$A_{m a x} = 2 (R^{2} \cos^{- 1} (1 - h / R) - (R - h) \sqrt{2 R h - h^{2}}),$

where:

R is the disc radius.
$h = R - \frac{t}{2},$ which is the width of each opening of either side of the disc.
t is the value of the Disc thickness parameter.

Tabulated Area

If you set Opening Characteristic to Tabulated, the block interpolates the valve opening from the Orifice area vector, Cv flow coefficient vector, Kv flow coefficient vector, or Sonic conductance vector parameters. The elements in these vectors correspond one-to-one to the elements in the Disc rotation vector parameter. The block interpolates between the data points by using linear interpolation and uses nearest extrapolation for points beyond the table boundaries.

Momentum Balance

The block equations depend on the Valve parametrization parameter. When you set Valve parametrization to Cv flow coefficient, the mass flow rate, $\dot{m}$ , is

$\dot{m} = C_{v} \frac{S_{o p e n}}{S_{M a x}} N_{6} Y \sqrt{(p_{i n} - p_{o u t}) ρ_{i n}},$

where:

C_v is the value of the Maximum Cv flow coefficient parameter.
S_open is the valve opening area.
S_Max is the maximum valve area when the valve is fully open.
N₆ is a constant equal to 27.3 for mass flow rate in kg/hr, pressure in bar, and density in kg/m³.
Y is the expansion factor.
p_in is the inlet pressure.
p_out is the outlet pressure.
ρ_in is the inlet density.

The expansion factor is

$Y = 1 - \frac{p_{i n} - p_{o u t}}{3 p_{i n} F_{γ} x_{T}},$

where:

F_γ is the ratio of the isentropic exponent to 1.4.
x_T is the value of the xT pressure differential ratio factor at choked flow parameter.

The block smoothly transitions to a linearized form of the equation when the pressure ratio, $p_{o u t} / p_{i n}$ , rises above the value of the Laminar flow pressure ratio parameter, B_lam,

$\dot{m} = C_{v} \frac{S_{o p e n}}{S_{M a x}} N_{6} Y_{l a m} \sqrt{\frac{ρ_{a v g}}{p_{a v g} (1 - B_{l a m})}} (p_{i n} - p_{o u t}),$

where:

$Y_{l a m} = 1 - \frac{1 - B_{l a m}}{3 F_{γ} x_{T}} .$

When the pressure ratio, $p_{o u t} / p_{i n}$ , falls below $1 - F_{γ} x_{T}$ , the orifice becomes choked and the block switches to the equation

$\dot{m} = \frac{2}{3} C_{v} \frac{S_{o p e n}}{S_{M a x}} N_{6} \sqrt{F_{γ} x_{T} p_{i n} ρ_{i n}} .$

When you set Valve parametrization to Kv flow coefficient, the block uses these same equations, but replaces C_v with K_v by using the relation $K_{v} = 0.865 C_{v}$ . For more information on the mass flow equations when the Valve parametrization parameter is Kv flow coefficient or Cv flow coefficient, [2][3].

When you set Valve parametrization to Sonic conductance, the mass flow rate, $\dot{m}$ , is

$\dot{m} = C \frac{S_{o p e n}}{S_{M a x}} ρ_{r e f} p_{i n} \sqrt{\frac{T_{r e f}}{T_{i n}}} {[1 - {(\frac{\frac{p_{o u t}}{p_{i n}} - B_{c r i t}}{1 - B_{c r i t}})}^{2}]}^{m},$

where:

C is the value of the Maximum sonic conductance parameter.
B_crit is the critical pressure ratio.
m is the value of the Subsonic index parameter.
T_ref is the value of the ISO reference temperature parameter.
ρ_ref is the value of the ISO reference density parameter.
T_in is the inlet temperature.

The block smoothly transitions to a linearized form of the equation when the pressure ratio, $p_{o u t} / p_{i n}$ , rises above the value of the Laminar flow pressure ratio parameter B_lam,

$\dot{m} = C \frac{S_{o p e n}}{S_{M a x}} ρ_{r e f} \sqrt{\frac{T_{r e f}}{T_{a v g}}} {[1 - {(\frac{B_{l a m} - B_{c r i t}}{1 - B_{c r i t}})}^{2}]}^{m} (\frac{p_{i n} - p_{o u t}}{1 - B_{l a m}}) .$

When the pressure ratio, $p_{o u t} / p_{i n}$ , falls below the critical pressure ratio, B_crit, the orifice becomes choked and the block switches to the equation

$\dot{m} = C \frac{S_{o p e n}}{S_{M a x}} ρ_{r e f} p_{i n} \sqrt{\frac{T_{r e f}}{T_{i n}}} .$

Only use the Sonic conductance setting of the Valve parameterization parameter for pneumatic applications. If you use this setting for moist air with high levels of trace gases or are modeling a fluid other than air, you may need to scale the sonic conductance by the square root of the mixture specific gravity. For more information on the mass flow equations when the Valve parametrization parameter is Sonic conductance, see [1].

When you set Valve parametrization to Orifice area based on geometry, the mass flow rate, $\dot{m}$ , is

$\dot{m} = C_{d} S_{o p e n} \sqrt{\frac{2 γ}{γ - 1} p_{i n} ρ_{i n} {(\frac{p_{o u t}}{p_{i n}})}^{\frac{2}{γ}} [\frac{1 - {(\frac{p_{o u t}}{p_{i n}})}^{\frac{γ - 1}{γ}}}{1 - {(\frac{S_{o p e n}}{S})}^{2} {(\frac{p_{o u t}}{p_{i n}})}^{\frac{2}{γ}}}]},$

where:

S_open is the valve opening area.
S is the value of the Cross-sectional area at ports A and B parameter.
C_d is the value of the Discharge coefficient parameter.
γ is the isentropic exponent.

The block smoothly transitions to a linearized form of the equation when the pressure ratio, $p_{o u t} / p_{i n}$ , rises above the value of the Laminar flow pressure ratio parameter, B_lam,

$\dot{m} = C_{d} S_{o p e n} \sqrt{\frac{2 γ}{γ - 1} p_{a v g}^{\frac{2 - γ}{γ}} ρ_{a v g} B_{l a m}^{\frac{2}{γ}} [\frac{1 - B_{l a m}^{\frac{γ - 1}{γ}}}{1 - {(\frac{S_{o p e n}}{S})}^{2} B_{l a m}^{\frac{2}{γ}}}]} (\frac{p_{i n}^{\frac{γ - 1}{γ}} - p_{o u t}^{\frac{γ - 1}{γ}}}{1 - B_{l a m}^{\frac{γ - 1}{γ}}}) .$

When the pressure ratio, $p_{o u t} / p_{i n}$ , falls below ${(\frac{2}{γ + 1})}^{\frac{γ}{γ - 1}}$ , the orifice becomes choked and the block switches to the equation

$\dot{m} = C_{d} S_{o p e n} \sqrt{\frac{2 γ}{γ + 1} p_{i n} ρ_{i n} \frac{1}{{(\frac{γ + 1}{2})}^{\frac{2}{γ - 1}} - {(\frac{S_{o p e n}}{S})}^{2}}} .$

For more information on the mass flow equations when the Valve parametrization parameter is Orifice area based on geometry, see [4].

Mass Balance

The block conserves mass through the valve

$\begin{array}{l} {\dot{m}}_{A} + {\dot{m}}_{B} = 0 \\ {\dot{m}}_{w A} + {\dot{m}}_{w B} = 0 \\ {\dot{m}}_{g A} + {\dot{m}}_{g B} = 0 \\ {\dot{m}}_{d A} + {\dot{m}}_{d B} = 0 \end{array}$

where ṁ is the mass flow rate and the subscript w denotes water vapor, the subscript g denotes trace gas, and the subscript d denotes water droplets.

Energy Balance

Because the block is an adiabatic component, no heat exchange occurs between the fluid and the wall that surrounds it. No work is done on or by the fluid as it traverses from inlet to outlet. Energy can flow only by advection through ports A and B. By the principle of conservation of energy, the sum of the port energy flows is always equal to zero,

$ϕ_{A} + ϕ_{B} = 0,$

where ϕ is the energy flow rate into the valve through ports A or B.

Assumptions and Limitations

This block does not model supersonic flow.

Ports

Input

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S — Valve position, rad
physical signal

Physical signal port associated with the position of the valve, in rad. A value of 0 represents a fully shut valve and a value of π/2 represents a fully open valve.

Programmatic Use

Port: S

Conserving

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A — Valve inlet or outlet
moist air

Moist air conserving port associated with the valve inlet or outlet.

Programmatic Use

Port: A

B — Valve inlet or outlet
moist air

Moist air conserving port associated with the valve inlet or outlet.

Programmatic Use

Port: B

Parameters

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Valve parameterization — Flow characteristics of valve
`Orifice area based on geometry` (default) | `Cv flow coefficient` | `Kv flow coefficient` | `Sonic conductance`

Method to use to calculate the mass flow rate of the valve:

Cv flow coefficient — The flow coefficient C_v determines the block parameterization.
Kv flow coefficient — The flow coefficient K_v, where $K_{v} = 0.865 C_{v}$ , determines the block parameterization.
Sonic conductance — The sonic conductance of the resistive element at steady state determines the block parameterization.
Orifice area — The size of the flow restriction determines the block parametrization.

Programmatic Use

Parameter:	`valve_parameterization`
Values:	`"fluids.moist_air.valves_orifices.flow_control_valves.enum.OrificeParameterization.Geometry"` \| `"fluids.moist_air.valves_orifices.flow_control_valves.enum.OrificeParameterization.Cv"` \| `"fluids.moist_air.valves_orifices.flow_control_valves.enum.OrificeParameterization.Kv"` \| `"fluids.moist_air.valves_orifices.flow_control_valves.enum.OrificeParameterization.SonicConductance"`

Opening characteristic — Method to use to determine the opening area
`Area of projected ellipses` (default) | `Tabulated`

Method to use to parameterize the block by using the method of area of projected ellipses or by using tabulated data.

Programmatic Use

Parameter:	`opening_characteristic`
Values:	`"fluids.moist_air.valves_orifices.flow_control_valves.enum.ButterflyValveSpec.Tabulated"` \| `"fluids.moist_air.valves_orifices.flow_control_valves.enum.ButterflyValveSpec.ProjectedEllipse"`

Orifice area vector — Flow area for disc rotations
`[1e-10, 45, 90, 135, 180, 225, 270, 315, 360, 405, 450]` `mm^2` (default) | vector of positive numbers

Flow area for a given disc rotation. Each element corresponds one-to-one with the elements in the Disc rotation vector parameter. The first element is the valve leakage and must be nonzero.

Dependencies

To enable this parameter, set Valve parameterization to Orifice area based on geometry and Opening characteristic to Tabulated.

Programmatic Use

Parameter: area_TLU

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 restriction area available for flow is at a maximum. This parameter measures the ease with which the moist air traverses the resistive element when driven by a pressure differential.

Dependencies

To enable this parameter, set Valve parameterization to Cv flow coefficient and Opening characteristic to Area of projected ellipses.

Programmatic Use

Parameter: Cv_max

Cv flow coefficient vector — C_v coefficients that correspond to values in disc rotation vector
`[1e-06, .0725, .1437, .2375, .35, .5375, .875, 1.3125, 2.125, 3.25, 4]` `1` (default) | vector of positive numbers

Vector of C_v flow coefficients. Each coefficient corresponds to an element in the Disc rotation vector parameter. This parameter measures the ease with which the moist air traverses the resistive element when driven by a pressure differential. The size of the vector must be the same as the Disc rotation vector parameter.

Dependencies

To enable this parameter, set Valve parameterization to Cv flow coefficient and Opening characteristic to Tabulated.

Programmatic Use

Parameter: Cv_TLU

Disc rotation vector — Values at which to specify tabulated parameter data
`pi / 2 * (0 : 0.1 : 1)` `rad` (default)

Disc rotation for a given flow coefficient or area. The elements in this vector must correspond one-to-one with the elements in either the Cv flow coefficient vector, Kv flow coefficient vector, Sonic conductance vector, or Orifice area vector parameters. The elements in this vector must increase monotonically from left to right.

Dependencies

To enable this parameter, set Opening characteristic to Tabulated.

Programmatic Use

Parameter: rotation_Cv_TLU

Parameter: rotation_Kv_TLU

Parameter: rotation_C_TLU

Parameter: rotation_area_TLU

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 restriction area available for the flow is at a maximum. This parameter measures the ease with which the moist air traverses the resistive element when driven by a pressure differential.

Dependencies

To enable this parameter, set Valve parameterization to Kv flow coefficient and Opening characteristic to Area of projected ellipses.

Programmatic Use

Parameter: Kv_max

Kv flow coefficient vector — K_v coefficients that correspond to values in disc rotation vector
`[1e-06, .0653, .1293, .2137, .315, .4838, .7875, 1.1813, 1.8381, 2.8112, 3.6]` (default) | vector of positive numbers

Vector of K_v flow coefficients. Each coefficient corresponds to an element in the Disc rotation vector parameter. This parameter measures the ease with which the moist air traverses the resistive element when driven by a pressure differential. The size of the vector must be the same as the Disc rotation vector parameter.

Dependencies

To enable this parameter, set Valve parameterization to Kv flow coefficient and Opening characteristic to Tabulated.

Programmatic Use

Parameter: Kv_TLU

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 $(p_{i n} - p_{o u t}) / p_{i n}$ where choking first occurs. If you do not have this value, look it up in table 2 in ISA-75.01.01 [3]. Otherwise, use the default value of 0.7.

Dependencies

To enable this parameter, set Valve parameterization to Cv flow coefficient or Kv flow coefficient.

Programmatic Use

Parameter: xT_Cv

Parameter: xT_Kv

Maximum sonic conductance — Sonic conductance that corresponds to maximally open component
`12` `l/(bar*s)` (default) | positive scalar

Value of the sonic conductance when the cross-sectional area available for flow is at a maximum.

Dependencies

To enable this parameter, set Valve parameterization to Sonic conductance and Opening characteristic to Area of projected ellipses.

Programmatic Use

Parameter: C_max

Critical pressure ratio — Ratio of downstream and upstream pressures at which flow first chokes
`0.3` (default) | positive scalar

Pressure ratio at which flow first begins to choke and the flow velocity reaches its maximum, given by the local speed of sound. The pressure ratio is the outlet pressure divided by the inlet pressure.

Dependencies

To enable this parameter, set Valve parameterization to Sonic conductance and Opening characteristic to Area of projected ellipses.

Programmatic Use

Parameter: B_crit_C

Sonic conductance vector — Sonic conductances that correspond to values in disc rotation vector
`[1e-05, .2175, .4312, .7125, 1.05, 1.6125, 2.625, 3.9375, 6.375, 9.75, 12]` `l/(bar*s)` (default) | vector of positive numbers

Vector of sonic conductances. Each conductance corresponds to an element in the Disc rotation vector parameter. The size of the vector must be the same as the Disc rotation vector parameter.

Dependencies

To enable this parameter, set Valve parameterization to Sonic conductance and Opening characteristic to Tabulated.

Programmatic Use

Parameter: C_TLU

Critical pressure ratio vector — Critical pressure ratios that correspond to values in disc rotation vector
`0.3 * ones(1, 11)` (default) | vector of positive numbers

Vector of critical pressure ratios at which the flow first chokes. Each critical pressure ratio corresponds to an element in the Disc rotation vector parameter. The critical pressure ratio is the fraction of downstream-to-upstream pressures at which the flow velocity reaches the local speed of sound. The size of the vector must be the same as the Disc rotation vector parameter.

Dependencies

To enable this parameter, set Valve parameterization to Sonic conductance and Opening characteristic to Tabulated.

Programmatic Use

Parameter: B_crit_TLU

Subsonic index — Exponent to use to calculate mass flow in subsonic flow regime
`0.5` (default) | positive scalar

Empirical value to use to calculate the mass flow rate in the subsonic flow regime.

Dependencies

To enable this parameter, set Valve parameterization to Sonic conductance.

Programmatic Use

Parameter: m

ISO reference temperature — ISO 8778 reference temperature
`293.15 K` (default) | scalar

Temperature at standard reference atmosphere, defined as 293.15 K in ISO 8778.

Dependencies

To enable this parameter, set Valve parameterization to Sonic conductance.

Programmatic Use

Parameter: T_ref_C

ISO reference density — ISO 8778 reference density
`1.185 kg/m^3` (default) | positive scalar

Density at standard reference atmosphere, defined as 1.185 kg/m3 in ISO 8778.

Dependencies

To enable this parameter, set Valve parameterization to Sonic conductance.

Programmatic Use

Parameter: rho_ref_C

Disc area — Area of disc
`pi * (0.02 ^ 2) / 4` `m^2` (default) | positive scalar

Surface area of one flat side of the disc.

Dependencies

To enable this parameter, set Opening characteristic to Area of projected ellipses.

Programmatic Use

Parameter: disc_area

Disc thickness — Disc thickness
`0` `m` (default) | positive scalar

Thickness of valve disc.

Dependencies

To enable this parameter, set Opening characteristic to Area of projected ellipses.

Programmatic Use

Parameter: disc_thickness

Cross-sectional area at ports A and B — Flow area at moist air ports
`pi * (0.025 ^ 2) / 4` `m^2` (default) | positive scalar

Cross-sectional area of the valve ports.

Programmatic Use

Parameter: area

Discharge coefficient — Discharge coefficient
`0.64` (default) | positive scalar in the range of [0,1]

Correction factor that accounts for discharge losses in theoretical flows.

Dependencies

To enable this parameter, set Valve parameterization to Orifice area based on geometry.

Programmatic Use

Parameter: Cd

Leakage flow fraction — Ratio of flow rate
`1e-6` (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 Opening characteristic to Area of projected ellipses.

Programmatic Use

Parameter: leakage_fraction

Smoothing factor — Numerical smoothing factor
`0.01` (default) | positive scalar

Continuous smoothing factor that introduces a layer of gradual change to the flow response when the valve is in near-open or near-closed positions. Set this parameter to a nonzero value less than one to increase the stability of your simulation in these regimes.

Dependencies

To enable this parameter, set Opening characteristic to Area of projected ellipses.

Programmatic Use

Parameter: smoothing_factor

Laminar flow pressure ratio — Pressure ratio at which flow transitions between laminar and turbulent regimes
`0.999` (default) | positive scalar

Pressure ratio at which the flow transitions between the laminar and turbulent flow regimes. The pressure ratio is the outlet pressure divided by inlet pressure. Typical values range from 0.995 to 0.999.

Programmatic Use

Parameter: B_lam

References

[1] ISO 6358-3. "Pneumatic fluid power – Determination of flow-rate characteristics of components using compressible fluids – Part 3: Method for calculating steady-state flow rate characteristics of systems". 2014.

[2] IEC 60534-2-3. "Industrial-process control valves – Part 2-3: Flow capacity – Test procedures". 2015.

[3] ANSI/ISA-75.01.01. "Industrial-Process Control Valves – Part 2-1: Flow capacity – Sizing equations for fluid flow underinstalled conditions". 2012.

[4] P. Beater. Pneumatic Drives. Springer-Verlag Berlin Heidelberg. 2007.

Extended Capabilities

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Version History

Introduced in R2026b

Butterfly Valve (MA)

Description

Valve Parameterizations

Opening Area

Momentum Balance

Mass Balance

Energy Balance

Assumptions and Limitations

Ports

Input

S — Valve position, rad physical signal

Programmatic Use

Conserving

A — Valve inlet or outlet moist air

Programmatic Use

B — Valve inlet or outlet moist air

Programmatic Use

Parameters

Valve parameterization — Flow characteristics of valve Orifice area based on geometry (default) | Cv flow coefficient | Kv flow coefficient | Sonic conductance

Programmatic Use

Opening characteristic — Method to use to determine the opening area Area of projected ellipses (default) | Tabulated

Programmatic Use

Orifice area vector — Flow area for disc rotations [1e-10, 45, 90, 135, 180, 225, 270, 315, 360, 405, 450] mm^2 (default) | vector of positive numbers

Dependencies

Programmatic Use

Maximum Cv flow coefficient — Cv coefficient that corresponds to maximally open component 4 (default) | positive scalar

Dependencies

Programmatic Use

Cv flow coefficient vector — Cv coefficients that correspond to values in disc rotation vector [1e-06, .0725, .1437, .2375, .35, .5375, .875, 1.3125, 2.125, 3.25, 4] 1 (default) | vector of positive numbers

Dependencies

Programmatic Use

Disc rotation vector — Values at which to specify tabulated parameter data pi / 2 * (0 : 0.1 : 1) rad (default)

Dependencies

Programmatic Use

Maximum Kv flow coefficient — Kv coefficient that corresponds to maximally open component 3.6 (default) | positive scalar

Dependencies

Programmatic Use

Kv flow coefficient vector — Kv coefficients that correspond to values in disc rotation vector [1e-06, .0653, .1293, .2137, .315, .4838, .7875, 1.1813, 1.8381, 2.8112, 3.6] (default) | vector of positive numbers

Dependencies

Programmatic Use

xT pressure differential ratio factor at choked flow — Ratio of pressure differentials 0.7 (default) | positive scalar

Dependencies

Programmatic Use

Maximum sonic conductance — Sonic conductance that corresponds to maximally open component 12 l/(bar*s) (default) | positive scalar

Dependencies

Programmatic Use

Critical pressure ratio — Ratio of downstream and upstream pressures at which flow first chokes 0.3 (default) | positive scalar

Dependencies

Programmatic Use

Sonic conductance vector — Sonic conductances that correspond to values in disc rotation vector [1e-05, .2175, .4312, .7125, 1.05, 1.6125, 2.625, 3.9375, 6.375, 9.75, 12] l/(bar*s) (default) | vector of positive numbers

Dependencies

Programmatic Use

Critical pressure ratio vector — Critical pressure ratios that correspond to values in disc rotation vector 0.3 * ones(1, 11) (default) | vector of positive numbers

Dependencies

Programmatic Use

Subsonic index — Exponent to use to calculate mass flow in subsonic flow regime 0.5 (default) | positive scalar

Dependencies

Programmatic Use

ISO reference temperature — ISO 8778 reference temperature 293.15 K (default) | scalar

Dependencies

Programmatic Use

ISO reference density — ISO 8778 reference density 1.185 kg/m^3 (default) | positive scalar

Dependencies

Programmatic Use

Disc area — Area of disc pi * (0.02 ^ 2) / 4 m^2 (default) | positive scalar

Dependencies

Programmatic Use

Disc thickness — Disc thickness 0 m (default) | positive scalar

Dependencies

Programmatic Use

Cross-sectional area at ports A and B — Flow area at moist air ports pi * (0.025 ^ 2) / 4 m^2 (default) | positive scalar

Programmatic Use

Discharge coefficient — Discharge coefficient 0.64 (default) | positive scalar in the range of [0,1]

Dependencies

Programmatic Use

Leakage flow fraction — Ratio of flow rate 1e-6 (default) | positive scalar

Dependencies

Programmatic Use

Smoothing factor — Numerical smoothing factor 0.01 (default) | positive scalar

Dependencies

S — Valve position, rad
physical signal

A — Valve inlet or outlet
moist air

B — Valve inlet or outlet
moist air

Valve parameterization — Flow characteristics of valve
`Orifice area based on geometry` (default) | `Cv flow coefficient` | `Kv flow coefficient` | `Sonic conductance`

Opening characteristic — Method to use to determine the opening area
`Area of projected ellipses` (default) | `Tabulated`

Orifice area vector — Flow area for disc rotations
`[1e-10, 45, 90, 135, 180, 225, 270, 315, 360, 405, 450]` `mm^2` (default) | vector of positive numbers

Maximum Cv flow coefficient — C_v coefficient that corresponds to maximally open component
`4` (default) | positive scalar

Cv flow coefficient vector — C_v coefficients that correspond to values in disc rotation vector
`[1e-06, .0725, .1437, .2375, .35, .5375, .875, 1.3125, 2.125, 3.25, 4]` `1` (default) | vector of positive numbers

Disc rotation vector — Values at which to specify tabulated parameter data
`pi / 2 * (0 : 0.1 : 1)` `rad` (default)

Maximum Kv flow coefficient — K_v coefficient that corresponds to maximally open component
`3.6` (default) | positive scalar

Kv flow coefficient vector — K_v coefficients that correspond to values in disc rotation vector
`[1e-06, .0653, .1293, .2137, .315, .4838, .7875, 1.1813, 1.8381, 2.8112, 3.6]` (default) | vector of positive numbers

xT pressure differential ratio factor at choked flow — Ratio of pressure differentials
`0.7` (default) | positive scalar

Maximum sonic conductance — Sonic conductance that corresponds to maximally open component
`12` `l/(bar*s)` (default) | positive scalar

Critical pressure ratio — Ratio of downstream and upstream pressures at which flow first chokes
`0.3` (default) | positive scalar

Sonic conductance vector — Sonic conductances that correspond to values in disc rotation vector
`[1e-05, .2175, .4312, .7125, 1.05, 1.6125, 2.625, 3.9375, 6.375, 9.75, 12]` `l/(bar*s)` (default) | vector of positive numbers

Critical pressure ratio vector — Critical pressure ratios that correspond to values in disc rotation vector
`0.3 * ones(1, 11)` (default) | vector of positive numbers

Subsonic index — Exponent to use to calculate mass flow in subsonic flow regime
`0.5` (default) | positive scalar

ISO reference temperature — ISO 8778 reference temperature
`293.15 K` (default) | scalar

ISO reference density — ISO 8778 reference density
`1.185 kg/m^3` (default) | positive scalar

Disc area — Area of disc
`pi * (0.02 ^ 2) / 4` `m^2` (default) | positive scalar

Disc thickness — Disc thickness
`0` `m` (default) | positive scalar

Cross-sectional area at ports A and B — Flow area at moist air ports
`pi * (0.025 ^ 2) / 4` `m^2` (default) | positive scalar

Discharge coefficient — Discharge coefficient
`0.64` (default) | positive scalar in the range of [0,1]

Leakage flow fraction — Ratio of flow rate
`1e-6` (default) | positive scalar

Smoothing factor — Numerical smoothing factor
`0.01` (default) | positive scalar

Laminar flow pressure ratio — Pressure ratio at which flow transitions between laminar and turbulent regimes
`0.999` (default) | positive scalar

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