Pressure Reducing Valve (TL)

Pressure reducing valve in a thermal liquid network

Libraries:
Simscape / Fluids / Thermal Liquid / Valves & Orifices / Pressure Control Valves

Description

The Pressure Reducing Valve (TL) block represents a valve that reduces downstream pressure in a thermal liquid network. The valve remains open when the pressure at port B is less than a specified pressure. When the pressure at port B meets or surpasses this pressure, the valve closes. The block operates based on the differential between the set pressure and the pressure at port B. The block contains a check valve portion that functions identically to the Check Valve (TL) block during flow reversals.

Pressure Control

The block regulates pressure between the set pressure and maximum pressure. When you set Set pressure control to:

Controlled — You can connect a pressure signal to port Ps. The block regulates pressure when the pressure at port B is greater than the reference set pressure, P_set, and below P_max. The pressure at port B acts as the control pressure, P_control, for this valve.
P_max is the sum of P_set and the pressure regulation range.
Constant — The Set pressure (gauge) parameter defines a constant set pressure.

The normalized pressure, $\hat{p}$ , controls the valve opening area when Opening parameterization is Linear - Area vs. pressure. The normalized pressure is

$\hat{p} = \frac{p_{c o n t r o l} - p_{s e t}}{p_{m a x} - p_{s e t}},$

where:

p_control is the control pressure, p_B ̶ p_Atm, where p_Atm is the atmospheric pressure.
p_set is the valve set pressure

$p_{s e t} = p_{s e t, g a u g e} + p_{A t m},$
where P_set,gauge is the value of the Set pressure (gauge) parameter.
p_max is the maximum pressure, p_max = p_set + p_range, where p_range is the value of the Pressure regulation range parameter.

Opening Parameterization

The mass flow rate depends on the value of the Opening parameterization parameter.

Area vs. Pressure Parameterizations

When you set Opening parameterization to Linear - Area vs. pressure or Tabulated data - Area vs. pressure, the mass flow rate is

$\dot{m} = \frac{C_{d} A_{v a l v e} \sqrt{2 \bar{ρ}}}{\sqrt{P R_{l o s s} (1 - {(\frac{A_{v a l v e}}{A_{p o r t}})}^{2})}} \frac{Δ p}{{[Δ p^{2} + Δ p_{c r i t}^{2}]}^{1 / 4}},$

where:

C_d is the value of the Discharge coefficient parameter.
A_valve is the instantaneous valve open area.
A_port is the value of the Cross-sectional area at ports A and B parameter.
$\bar{ρ}$ is the average fluid density.
Δp is the valve pressure difference p_A – p_B.

The critical pressure difference, Δp_crit, is the pressure differential associated with the Critical Reynolds number, Re_crit, the flow regime transition point between laminar and turbulent flow:

$Δ p_{c r i t} = \frac{π}{8 A_{v a l v e} \bar{ρ}} {(\frac{μ {Re}_{c r i t}}{C_{d}})}^{2},$

where μ is the dynamic viscosity of the thermal liquid.

The pressure loss, PR_loss, describes the reduction of pressure in the valve due to a decrease in area. The block calculates PR_loss as

$P R_{l o s s} = \frac{\sqrt{1 - {(\frac{A_{v a l v e}}{A_{p o r t}})}^{2} (1 - C_{d}^{2})} - C_{d} \frac{A_{v a l v e}}{A_{p o r t}}}{\sqrt{1 - {(\frac{A_{v a l v e}}{A_{p o r t}})}^{2} (1 - C_{d}^{2})} + C_{d} \frac{A_{v a l v e}}{A_{p o r t}}} .$

The pressure recovery describes the positive pressure change in the valve due to an increase in area. When you clear the Pressure recovery check box, the block sets PR_loss to 1.

When you set the Opening parameterization parameter to Linear - Area vs. pressure, the block calculates the opening area as

$A_{v a l v e} = \hat{p} (A_{l e a k} - A_{m a x}) + A_{m a x},$

where A_leak is the value of the Leakage Area parameter and A_max is the value of the Maximum opening area parameter.

This figure shows how the block controls the opening area using the linear parameterization.

Pressure differential between ports X and Y with respect to opening area for a normally open valve using the linear parameterization

When the valve is in a near-open or near-closed 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 control pressure between p_set and p_max. For more information, see Numerical Smoothing.

When you set Opening parameterization to Tabulated data - Area vs. pressure, the block calculates the opening area as

$A_{v a l v e} = t a b l e l o o k u p (p_{c o n t r o l, T L U, r e f}, A_{T L U}, p_{c o n t r o l}, i n t e r p o l a t i o n = l i n e a r, e x t r a p o l a t i o n = n e a r e s t),$

where:

p_{control,TLU,ref} = p_TLU + p_offset.
p_TLU is the Pressure differential vector parameter.
p_offset is an internal pressure offset that causes the valve to start closing when p_{control,TLU,ref} = p_set.
A_TLU is the Opening area vector parameter.

This figure shows how the block controls the opening area when Opening parameterization is Tabulated data - Area vs. pressure.

Pressure differential between ports X and Y with respect to opening area for a normally open valve using the tabulated parameterization

Volumetric Flow Rate vs. Pressure Parameterization

When you set Opening parameterization to Tabulated data - Volumetric flow rate vs. pressure, the valve opens according to the user-provided tabulated data of volumetric flow rate and pressure differential between ports A and B.

The block calculates the mass flow rate as

$\dot{m} = \bar{ρ} \dot{V},$

where:

$\dot{V}$ is the volumetric flow rate.
$\bar{ρ}$ is the average fluid density.

The block calculates the relationship between the mass flow and pressure using

$\dot{m} = K \bar{ρ} \sqrt{Δ p},$

where

$K= \frac{\dot{V}}{\sqrt{| Δ p |}} .$

Opening Dynamics

When you select Opening dynamics, the block introduces a control pressure lag where p_control becomes the dynamic control pressure, p_dyn. The instantaneous change in dynamic opening area is calculated based on the Opening time constant parameter, τ:

${\dot{p}}_{d y n} = \frac{p_{c o n t r o l} - p_{d y n}}{τ} .$

By default, the block clears the Opening dynamics check box.

Energy Balance

The energy conservation equation in the valve is

$ϕ_{A} + ϕ_{B} = 0,$

where:

ϕ_A is the energy flow rate into the valve through port A.
ϕ_B is the energy flow rate into the valve through port B.

Faults

To model a fault, in the Faults section, click the Add fault hyperlink next to the fault that you want to model. Use the fault parameters to specify the fault properties. For more information about fault modeling, see Introduction to Simscape Faults.

Three fault options are available for the reducing valve and check valve. For the Reducing valve opening when faulted and Check valve opening when faulted parameters, you can choose:

Closed — The valve shuts to its smallest opening value, depending on the Opening parameterization parameter. When you set Opening parameterization to:
- Linear - Area vs. pressure — The valve area reduces to the value of the Leakage area parameter.
- Tabulated data - Area vs. pressure — The valve area reduces to the value of the last element in the Opening area vector parameter.
- Tabulated data - Volumetric flow rate vs. pressure — The flow coefficient reduces to the value of the last element of the derived flow coefficient lookup table, K_TLU,Ref.
Open — The valve opens to its largest opening value, depending on the Opening parameterization parameter. When you set Opening parameterization to:
- Linear - Area vs. pressure — The valve area opens to the value of the Maximum opening area.
- Tabulated data - Area vs. pressure — The valve area opens to the value of the first element in the Opening area vector.
- Tabulated data - Volumetric flow rate vs. pressure — The flow coefficient reduces to the value of the first element of the derived flow coefficient lookup table, K_TLU,Ref.
Maintain last value — The valve area remains at the valve opening area when the trigger occurred.

For the linear parameterization, numerical smoothing at the extremes of the valve area causes the minimum area applied to be larger than the Leakage area parameter, and the maximum is smaller than the Maximum orifice area parameter.

After the fault triggers, the valve remains at the faulted area for the rest of the simulation.

Predefined Parameterization

You can populate the block with pre-parameterized manufacturing data, which allows you to model a specific supplier component.

To load a predefined parameterization:

In the block dialog box, next to Selected part, click the "<click to select>" hyperlink next to Selected part in the block dialogue box settings.
The Block Parameterization Manager window opens. Select a part from the menu and click Apply all. You can narrow the choices using the Manufacturer drop down menu.
You can close the Block Parameterization Manager menu. The block now has the parameterization that you specified.
You can compare current parameter settings with a specific supplier component in the Block Parameterization Manager window by selecting a part and viewing the data in the Compare selected part with block section.

Note

Predefined block parameterizations use available data sources to supply parameter values. The block substitutes engineering judgement and simplifying assumptions for missing data. As a result, expect some deviation between simulated and actual physical behavior. To ensure accuracy, validate the simulated behavior against experimental data and refine your component models as necessary.

To learn more, see List of Pre-Parameterized Components.

Ports

Input

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Ps — Set pressure signal, Pa
physical signal

Pressure threshold for controlled valve operation, in Pa.

Dependencies

To enable this port, set Set pressure control to Controlled.

Conserving

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A — Liquid port
thermal liquid

Thermal liquid conserving port associated with valve inlet A.

B — Liquid port
thermal liquid

Thermal liquid conserving port associated with valve inlet B.

Parameters

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Parameters

Opening parameterization — Opening parameterization
`Linear - Area vs. pressure` (default) | `Tabulated data - Area vs. pressure` | `Tabulated data - Volumetric flow rate vs. pressure`

Method of modeling the opening of the valve. When you set this parameter to Linear - Area vs. pressure or Tabulated data - Area vs. pressure, the block relates the opening area to the control pressure. When you set this parameter to Tabulated data - Volumetric flow rate vs. pressure, the block takes the reference flow rate and pressure differential curve of the reducing valve.

Set pressure control — Valve operation method
`Constant` (default) | `Controlled`

Valve operation method. When you set this parameter to Constant, the valve closes linearly over a fixed pressure regulation range or in accordance with the tabulated pressure and opening area data that you provide. When you set this parameter to Controlled, the valve closes according to a variable set pressure signal at port Ps over a fixed pressure regulation range.

Set pressure (gauge) — Gauge pressure at which the valve begins to shut
`0.1` `MPa` (default) | positive scalar

Pressure at which the valve begins to shut. The opening area remains variable throughout the pressure regulation range of the valve.

Dependencies

To enable this parameter, set Set pressure control to Constant.

Pressure regulation range — Valve pressure range
`0.01` `MPa` (default) | positive scalar

Pressure interval over which the valve opening area varies. The interval begins at the value of the Set pressure (gauge) parameter.

Dependencies

To enable this parameter, set Opening parameterization to Linear - Area vs. pressure.

Maximum opening area — Opening area in fully open position
`1e-4` `m^2` (default) | positive scalar

Opening area of the valve in the fully open position due to sealing imperfections, when the valve is at the lower limit of the pressure regulation range. The block uses this parameter to scale the valve opening throughout the pressure regulation range.

Dependencies

To enable this parameter, set Opening parameterization to Linear - Area vs. pressure.

Leakage area — Gap area when in fully closed position
`1e-10` `m^2` (default) | positive scalar

Sum of all gaps when the valve is in the fully shut position. The block saturates smaller numbers to this value. This parameter contributes to numerical stability by maintaining continuity in the flow.

Dependencies

To enable this parameter, set Opening parameterization to Linear - Area vs. pressure.

Pressure at port B (gauge) vector — Vector of gauge pressure values for tabulated area parameterization
`[0.2 : 0.2 : 1.2]` `MPa` (default) | 1-by-n vector

Vector of gauge pressure values for the tabulated area parameterization of the valve opening area. The vector elements must correspond one-to-one with the elements in the Opening area vector parameter. The elements must be positive and in ascending order. The block uses linear interpolation between the data points.

Dependencies

To enable this parameter, set Opening parameterization to Tabulated data - Area vs. pressure.

Opening area vector — Valve opening areas for tabulated area parameterization
`[1e-05, 8e-06, 6e-06, 4e-06, 2e-06, 1e-10]` `m^2` (default) | 1-by-n vector

Vector of valve opening areas for the tabulated area parameterization of the valve opening area. The vector elements must correspond one-to-one with the elements in the Pressure at Port B (gauge) vector parameter. The elements must be positive and in ascending order. The block uses linear interpolation between the data points.

Dependencies

To enable this parameter, set Opening parameterization to Tabulated data - Area vs. pressure.

Reference pressure at port A (gauge) — Reference pressure at port A
`1.5` `MPa` (default) | positive scalar

Constant pressure at port A that forms the basis of the reference curve. This value typically corresponds to the maximum operating pressure of the valve. The pressure at port A can be any value during simulation.

Dependencies

To enable this parameter, set Opening parameterization to Tabulated data - Volumetric flow rate vs. pressure.

Reference pressure at port B (gauge) vector — Reference pressure at port B
`[1.2, 1, .8, .6, .4, .2]` `MPa` (default) | 1-by-n vector

Vector of monotonically decreasing pressure values at port B in the reference curve as the valve opening area changes. The first element is the reference maximum pressure, which is the pressure where the valve fully shuts. The last element is the reference set pressure.

Dependencies

To enable this parameter, set Opening parameterization to Tabulated data - Volumetric flow rate vs. pressure.

Reference volumetric flow rate vector — Reference volumetric flow rate
`[1e-09, 1.8e-05, 6.6e-05, .00013, .0002, .00028]` `m^3/s` (default) | 1-by-n vector

Vector of monotonically increasing reference flow rates through the valve. The block uses this curve to generate a flow coefficient for the changing valve area.

Dependencies

To enable this parameter, set Opening parameterization to Tabulated data - Volumetric flow rate vs. pressure.

Cross-sectional area at ports A and B — Area at conserving ports
`0.01` `m^2` (default) | positive scalar

Area at ports A and B, which the block uses in the pressure-flow rate equation that determines the mass flow rate through the valve.

Discharge coefficient — Discharge coefficient
`0.64` (default) | positive scalar

Correction factor that the block uses to account for discharge losses in theoretical flows.

Dependencies

To enable this parameter, set Opening parameterization to Linear - Area vs. pressure or Tabulated data - Area vs. pressure.

Critical Reynolds number — Upper Reynolds number limit for laminar flow
`150` (default) | positive scalar

Upper Reynolds number limit for laminar flow through the valve.

Dependencies

To enable this parameter, set Opening parameterization to Linear - Area vs. pressure or Tabulated data - Area vs. pressure.

Smoothing factor — Numerical smoothing factor
`0.01` (default) | positive scalar in the range [0,1]

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 value to a nonzero value less than one to increase the stability of your simulation in these regimes.

Dependencies

To enable this parameter, set Opening parameterization to Linear - Area vs. pressure.

Pressure recovery — Option to include pressure increase during area expansions
`off` (default) | `on`

Whether to capture the increase in pressure when fluid flows from a region of smaller cross-sectional area to a region of larger cross-sectional area.

Dependencies

To enable this parameter, set Opening parameterization to Linear - Area vs. pressure or Tabulated data - Area vs. pressure.

Opening dynamics — Option to include flow response to valve opening
`off` (default) | `on`

Whether to approximate the transient effects to the fluid system due to valve opening. Selecting Opening dynamics approximates opening conditions by introducing a first-order lag in the flow response.

Opening time constant — Valve opening time constant
`0.1` `s` (default) | positive scalar

Time constant by which to compute the lag in the opening dynamics.

Dependencies

To enable this parameter, select Opening dynamics.

Check Valve

Enable check valve — Check valve option
`off` (default) | `on`

Whether the block simulates an internal check valve.

Cracking pressure differential — Set pressure for check valve operation
`0.1` `MPa` (default) | positive scalar

Pressure differential that lifts the check valve.

Dependencies

To enable this parameter, select Enable check valve and set Valve parameterization to Linear - Area vs. pressure.

Maximum opening pressure differential — Maximum pressure in valve
`0.2` `MPa` (default) | positive scalar

Pressure differential when the check valve fully shuts.

Dependencies

To enable this parameter, select Enable check valve and set Valve parameterization to Linear - Area vs. pressure.

Maximum opening area — Maximum open area
`1e-4` `m^2` (default) | positive scalar

Maximum open area of the check valve in the load line. Internally, the check valve is in parallel with the reducing stage.

Dependencies

To enable this parameter, select Enable check valve and set Valve parameterization to Linear - Area vs. pressure.

Pressure differential vector — Pressure differential for check valve operation
`[0.01 : 0.01 : 1]` `MPa` (default) | 1-by-n vector

Vector of pressure differentials for the check valve stage. The block computes the check valve pressure differential as pressure at port B with respect to pressure at port A.

Dependencies

To enable this parameter, select Enable check valve and set Valve parameterization to Tabulated data - Area vs. pressure or Tabulated data - Volumetric flow rate vs. pressure.

Opening area vector — Check stage opening areas
`[1e-10, 1e-05, 2e-05, 3e-05, 4e-05, 5e-05, 6e-05, 7.5e-05, 8.5e-05, .0001]` `m^2` (default) | 1-by-n vector

Vector of opening areas for the check valve stage. The vector elements must correspond one-to-one with the elements in the Pressure differential vector parameter.

Dependencies

To enable this parameter, select Enable check valve and set Valve parameterization to Tabulated data - Area vs. pressure.

Volumetric flow rate vector — Check stage volumetric flow rates
`[.000358, .045, .11, .191, .284, .39, .505, .63, .764, .905] .* 1e-3` `m^3/s` (default) | 1-by-n vector

Vector of volumetric flow rates for the check valve stage. The elements of this vector must correspond to the elements in the Pressure differential vector parameter.

Dependencies

To enable this parameter, select Enable check valve and set Valve parameterization to Tabulated data - Volumetric flow rate vs. pressure.

Faults

Pressure-Reducing Valve Area fault — Option to model reducing valve fault
`Add fault`

Option to enable the fault parameters for the reducing valve. To add a fault, click the Add fault hyperlink. When faulting occurs, the block sets the opening area to the position specified by the Reducing valve opening when faulted parameter.

Reducing valve opening when faulted — Reducing valve fault position
`Closed` (default) | `Open` | `Maintain last value`

Faulted reducing valve position. You can choose for the valve to fault while open, shut, or in place.

Dependencies

To enable this parameter, enable faults for the block by clicking the Add fault hyperlink for the Pressure-Reducing Valve Area fault parameter.

Check Valve Area fault — Option to model check valve fault
`Add fault`

Option to enable the fault parameters for the check valve. To add a fault, click the Add fault hyperlink. When a fault occurs, the block sets the opening area to the position specified by the Check valve opening when faulted parameter.

Dependencies

To enable this parameter, select Enable check valve.

Check valve opening when faulted — Faulted valve characteristics
`Closed` (default) | `Open` | `Maintain last value`

Faulted check valve position. You can choose for the valve to fault while open, shut, or in place.

Dependencies

To enable this parameter, select Enable check valve and enable faults for the block by clicking the Add fault hyperlink for the Check Valve Area fault parameter.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced in R2016a

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R2024b: Model faults with the Simscape faults interface

The Pressure Reducing Valve (TL) block now supports the Simscape faults interface. To learn more, see Introduction to Simscape Faults.

R2024b: New valve control options

Set Set pressure control to Controlled to control the block set pressure with the signal at port Ps. Select Enable check valve to model a check valve that functions identically to the Check Valve (TL) block during flow reversals.

R2023a: New Parameterization Options

Use the Opening parameterization parameter to choose the block parameterization Linear - Area vs. pressure, Tabulated data - Area vs. pressure, or Tabulated data - Volumetric flow rate vs. pressure.

Pressure Reducing Valve (TL)

Description

Pressure Control

Opening Parameterization

Opening Dynamics

Energy Balance

Faults

Predefined Parameterization

Ports

Input

Ps — Set pressure signal, Pa physical signal

Dependencies

Conserving

A — Liquid port thermal liquid

B — Liquid port thermal liquid

Parameters

Parameters

Opening parameterization — Opening parameterization Linear - Area vs. pressure (default) | Tabulated data - Area vs. pressure | Tabulated data - Volumetric flow rate vs. pressure

Set pressure control — Valve operation method Constant (default) | Controlled

Set pressure (gauge) — Gauge pressure at which the valve begins to shut 0.1 MPa (default) | positive scalar

Dependencies

Pressure regulation range — Valve pressure range 0.01 MPa (default) | positive scalar

Dependencies

Maximum opening area — Opening area in fully open position 1e-4 m^2 (default) | positive scalar

Dependencies

Leakage area — Gap area when in fully closed position 1e-10 m^2 (default) | positive scalar

Dependencies

Pressure at port B (gauge) vector — Vector of gauge pressure values for tabulated area parameterization [0.2 : 0.2 : 1.2] MPa (default) | 1-by-n vector

Dependencies

Opening area vector — Valve opening areas for tabulated area parameterization [1e-05, 8e-06, 6e-06, 4e-06, 2e-06, 1e-10] m^2 (default) | 1-by-n vector

Dependencies

Reference pressure at port A (gauge) — Reference pressure at port A 1.5 MPa (default) | positive scalar

Dependencies

Reference pressure at port B (gauge) vector — Reference pressure at port B [1.2, 1, .8, .6, .4, .2] MPa (default) | 1-by-n vector

Dependencies

Reference volumetric flow rate vector — Reference volumetric flow rate [1e-09, 1.8e-05, 6.6e-05, .00013, .0002, .00028] m^3/s (default) | 1-by-n vector

Dependencies

Cross-sectional area at ports A and B — Area at conserving ports 0.01 m^2 (default) | positive scalar

Discharge coefficient — Discharge coefficient 0.64 (default) | positive scalar

Dependencies

Critical Reynolds number — Upper Reynolds number limit for laminar flow 150 (default) | positive scalar

Dependencies

Smoothing factor — Numerical smoothing factor 0.01 (default) | positive scalar in the range [0,1]

Dependencies

Pressure recovery — Option to include pressure increase during area expansions off (default) | on

Dependencies

Opening dynamics — Option to include flow response to valve opening off (default) | on

Opening time constant — Valve opening time constant 0.1 s (default) | positive scalar

Dependencies

Check Valve

Enable check valve — Check valve option off (default) | on

Cracking pressure differential — Set pressure for check valve operation 0.1 MPa (default) | positive scalar

Dependencies

Maximum opening pressure differential — Maximum pressure in valve 0.2 MPa (default) | positive scalar

Dependencies

Maximum opening area — Maximum open area 1e-4 m^2 (default) | positive scalar

Dependencies

Pressure differential vector — Pressure differential for check valve operation [0.01 : 0.01 : 1] MPa (default) | 1-by-n vector

Dependencies

Opening area vector — Check stage opening areas [1e-10, 1e-05, 2e-05, 3e-05, 4e-05, 5e-05, 6e-05, 7.5e-05, 8.5e-05, .0001] m^2 (default) | 1-by-n vector

Dependencies

Volumetric flow rate vector — Check stage volumetric flow rates [.000358, .045, .11, .191, .284, .39, .505, .63, .764, .905] .* 1e-3 m^3/s (default) | 1-by-n vector

Dependencies

Faults

Pressure-Reducing Valve Area fault — Option to model reducing valve fault Add fault

Reducing valve opening when faulted — Reducing valve fault position Closed (default) | Open | Maintain last value

Dependencies

Check Valve Area fault — Option to model check valve fault Add fault

Dependencies

Check valve opening when faulted — Faulted valve characteristics Closed (default) | Open | Maintain last value

Dependencies

Extended Capabilities

C/C++ Code Generation Generate C and C++ code using Simulink® Coder™.

Version History

R2024b: Model faults with the Simscape faults interface

R2024b: New valve control options

R2023a: New Parameterization Options

See Also

Ps — Set pressure signal, Pa
physical signal

A — Liquid port
thermal liquid

B — Liquid port
thermal liquid

Opening parameterization — Opening parameterization
`Linear - Area vs. pressure` (default) | `Tabulated data - Area vs. pressure` | `Tabulated data - Volumetric flow rate vs. pressure`

Set pressure control — Valve operation method
`Constant` (default) | `Controlled`

Set pressure (gauge) — Gauge pressure at which the valve begins to shut
`0.1` `MPa` (default) | positive scalar

Pressure regulation range — Valve pressure range
`0.01` `MPa` (default) | positive scalar

Maximum opening area — Opening area in fully open position
`1e-4` `m^2` (default) | positive scalar

Leakage area — Gap area when in fully closed position
`1e-10` `m^2` (default) | positive scalar

Pressure at port B (gauge) vector — Vector of gauge pressure values for tabulated area parameterization
`[0.2 : 0.2 : 1.2]` `MPa` (default) | 1-by-n vector

Opening area vector — Valve opening areas for tabulated area parameterization
`[1e-05, 8e-06, 6e-06, 4e-06, 2e-06, 1e-10]` `m^2` (default) | 1-by-n vector

Reference pressure at port A (gauge) — Reference pressure at port A
`1.5` `MPa` (default) | positive scalar

Reference pressure at port B (gauge) vector — Reference pressure at port B
`[1.2, 1, .8, .6, .4, .2]` `MPa` (default) | 1-by-n vector

Reference volumetric flow rate vector — Reference volumetric flow rate
`[1e-09, 1.8e-05, 6.6e-05, .00013, .0002, .00028]` `m^3/s` (default) | 1-by-n vector

Cross-sectional area at ports A and B — Area at conserving ports
`0.01` `m^2` (default) | positive scalar

Discharge coefficient — Discharge coefficient
`0.64` (default) | positive scalar

Critical Reynolds number — Upper Reynolds number limit for laminar flow
`150` (default) | positive scalar

Smoothing factor — Numerical smoothing factor
`0.01` (default) | positive scalar in the range [0,1]

Pressure recovery — Option to include pressure increase during area expansions
`off` (default) | `on`

Opening dynamics — Option to include flow response to valve opening
`off` (default) | `on`

Opening time constant — Valve opening time constant
`0.1` `s` (default) | positive scalar

Enable check valve — Check valve option
`off` (default) | `on`

Cracking pressure differential — Set pressure for check valve operation
`0.1` `MPa` (default) | positive scalar

Maximum opening pressure differential — Maximum pressure in valve
`0.2` `MPa` (default) | positive scalar

Maximum opening area — Maximum open area
`1e-4` `m^2` (default) | positive scalar

Pressure differential vector — Pressure differential for check valve operation
`[0.01 : 0.01 : 1]` `MPa` (default) | 1-by-n vector

Opening area vector — Check stage opening areas
`[1e-10, 1e-05, 2e-05, 3e-05, 4e-05, 5e-05, 6e-05, 7.5e-05, 8.5e-05, .0001]` `m^2` (default) | 1-by-n vector

Volumetric flow rate vector — Check stage volumetric flow rates
`[.000358, .045, .11, .191, .284, .39, .505, .63, .764, .905] .* 1e-3` `m^3/s` (default) | 1-by-n vector

Pressure-Reducing Valve Area fault — Option to model reducing valve fault
`Add fault`

Reducing valve opening when faulted — Reducing valve fault position
`Closed` (default) | `Open` | `Maintain last value`

Check Valve Area fault — Option to model check valve fault
`Add fault`

Check valve opening when faulted — Faulted valve characteristics
`Closed` (default) | `Open` | `Maintain last value`

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.