Pressure Relief Valve (TL)

Pressure relief valve in a thermal liquid network

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

Description

The Pressure Relief Valve (TL) block represents a valve that relieves excess pressure in a thermal liquid network. The valve remains closed when the pressure is less than a specified value. When this pressure is met or surpassed, the valve opens. This set pressure is either a threshold pressure differential over the valve, between ports A and B, or between port A and atmospheric pressure. A control pressure above the set pressure causes the valve to gradually open, which allows the fluid network to relieve excess pressure.

Pressure Control

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, which depends on the value of the Pressure control specification parameter.
When you set Pressure control specification to Pressure differential, the control pressure is p_A ̶ p_B.
When you set Pressure control specification to Pressure at port A, the control pressure is the difference between the pressure at port A and atmospheric pressure.
p_set is the set pressure, which depends on the value of the Pressure control specification parameter.
When you set Pressure control specification to Pressure differential, p_set is the value of the Set pressure differential parameter.
When you set Set pressure specification to Pressure at port A, p_set 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 Set pressure control to Constant and 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 Opening parameterization to Linear - Area vs. pressure, the block calculates the opening area as

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

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 closed 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 or Opening pressure (gauge) vector parameter, depending on the value of the Pressure control specification 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 closed valve using the tabulated parameterization

Volumetric Flow Rate vs. Pressure Parameterization

When you set Set pressure control to Constant and 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

$K= \frac{\dot{V}}{\sqrt{| Δ p |}} .$

Controlled Pressure Regulation

When you set Set pressure control to Controlled, the normalized pressure is

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

where:

p_s is the value of the signal at port Ps.
p_max = p_s + p_range, where p_range is the value of the Pressure regulation range parameter.
p_control is the pressure differential between ports A and B, p_A ̶ p_B.

Opening Dynamics

When you set Opening dynamics to On, 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.

The Opening area when faulted parameter has three fault options:

Closed — The valve freezes at its smallest value:
- When you set Set pressure control to Constant and Opening parameterization to Linear - Area vs. pressure, the valve area freezes at the Leakage area parameter.
- When you set Set pressure control to Constant and Opening parameterization to Tabulated data - Area vs. pressure, the valve area freezes at the first element of the Opening area vector parameter.
- When you set Set pressure control to Controlled the valve area freezes at the Leakage area parameter.
Open — The valve freezes at its largest value:
- When you set Set pressure control to Constant and Opening parameterization to Linear - Area vs. pressure, the valve area freezes at the Maximum opening area parameter.
- When you set Set pressure control to Constant and Orifice parameterization to Tabulated data - Area vs. pressure, the valve area freezes at the last element of the Opening area vector parameter.
- When you set Set pressure control to Controlled the valve area freezes at the Maximum opening area parameter.
Maintain last value — The valve area freezes at the valve open area when the trigger occurred.

Due to numerical smoothing at the extremes of the valve area, the minimum area the block uses is larger than the Leakage area parameter, and the maximum is smaller than the Maximum orifice area parameter, in proportion to the Smoothing factor parameter value.

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

When you set Opening parameterization to Tabulated data - Volumetric flow rate vs. pressure, the fault options are defined by the volumetric flow rate through the valve:

Closed — The valve stops at the mass flow rate associated with the first elements of the Volumetric flow rate vector parameter and the Pressure drop vector parameter:

$\dot{m} = K_{L e a k} \bar{ρ} \sqrt{Δ p} .$
Open — The valve stops at the mass flow rate associated with the last elements of the Volumetric flow rate vector parameter and the Pressure drop vector parameter:

$\dot{m} = K_{M a x} \bar{ρ} \sqrt{Δ p}$
Maintain at last value — The valve stops at the mass flow rate and pressure differential when the trigger occurs:

$\dot{m} = K_{L a s t} \bar{ρ} \sqrt{Δ p},$

where

$K_{L a s t} = \frac{| \dot{m} |}{\bar{ρ} \sqrt{| Δ p |}} .$

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.

Examples

Reciprocal Actuator with Differential Cylinders

A double-acting actuator with differential cylinders. The pump output is connected to cylinder B of the actuator while cylinder A of the actuator can be connected to either the pump or the reservoir through the 3-way directional valve. When cylinder A is connected to the pump, pressures at both cylinders become equal. Because of the larger effective piston area in cylinder A, the interface force in cylinder A is larger than that of in cylinder B which causes the piston to extend. When cylinder A is connected to the reservoir, the piston starts to retract. The 3-way directional valve is controlled by a sinusoidal signal to achieve repeating reciprocal motion in the actuator.

Open Model

Ports

Input

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Ps — Set pressure signal, Pa
physical signal

Set pressure for controlled valve operation, in Pa.

Dependencies

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

Conserving

expand all

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

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

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

Dependencies

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

Opening parameterization — Method of modeling constant valve opening or closing
`Linear - Area vs. pressure` (default) | `Tabulated data - Area vs. pressure` | `Tabulated data - Volumetric flow rate vs. pressure`

Method of modeling the valve opening or closing. You can parameterize the valve opening linearly or by using a table of values that correlate the area-to-pressure differential.

Dependencies

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

Pressure control specification — Method to evaluate pressure
`Pressure at port A` (default) | `Pressure differential`

Specification method for the valve control pressure. When you set this parameter to Pressure at port A, the block uses only the pressure at port A to determine when the flow exceeds the value of the Set pressure (gauge) parameter. When you set this parameter Pressure differential, the block uses the value of the Set pressure differential parameter to determine whether the pressure differential from port A to port B exceeds the range.

Dependencies

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

Set pressure (gauge) — Gauge pressure when opening mechanism triggers
`0.1` `MPa` (default) | positive scalar

Pressure at which the opening mechanism triggers. The opening area remains variable throughout the pressure regulation range of the valve.

Dependencies

To enable this parameter, set Set pressure control to Constant and either:

Pressure control specification to Pressure at port A and Opening parameterization to Linear - Area vs. pressure.
Opening parameterization to Tabulated data - Volumetric flow rate vs. pressure.

Set pressure differential — Minimum opening pressure differential
`0` `MPa` (default) | nonnegative scalar

Minimum pressure differential between ports A and B required to open the valve. A pressure differential above this value causes the valve to gradually open until it reaches the fully open state.

Dependencies

To enable this parameter, set Set pressure control to Constant, Pressure control specification to Pressure differential, and Opening parameterization to Linear - Area vs. pressure.

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

Valve operational range. The valve begins to open at the set pressure value, and is fully open at p_max, the end of the pressure regulation range, where p_max = p_set + p_range.

Dependencies

To enable this parameter, set either:

Set pressure control to Controlled.
Set pressure control to Constant and 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 upper limit of the pressure regulation range.

Dependencies

To enable this parameter, set either:

Set pressure control to Controlled.
Set pressure control to Constant and Opening parameterization to Linear - Area vs. pressure.

Leakage area — Gap area when in fully shut 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 either:

Set pressure control to Controlled.
Set pressure control to Constant and Opening parameterization to Linear - Area vs. pressure.

Pressure differential vector — Differential pressure values for tabular parameterization
`[0.2 : 0.2 : 1.2]` MPa (default) | 1-by-n vector

Vector of pressure differential values for the tabular 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 listed in ascending order and must be greater than 0. The block employs linear interpolation between table data points.

The first element of this parameter is the pressure setting of the valve, at which the valve begins to open. The last element is the maximum pressure, at which the valve is fully open. The difference between the two is the pressure regulation range of the valve.

Dependencies

To enable this parameter, set Set pressure control to Constant and either:

Opening parameterization to Tabulated data - Volumetric flow rate vs. pressure.
Opening parameterization to Tabulated data - Area vs. pressure and Pressure control specification to Pressure differential.

Opening pressure (gauge) vector — Differential pressure values for tabular area parameterization
`[0.2 : 0.2 : 1.2]` MPa (default) | 1-by-n vector

Vector of pressure differential values for the tabular 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 are must be in ascending order and must be greater than 0. The block employs linear interpolation between table data points.

Dependencies

To enable this parameter, set Set pressure control to Constant, Opening parameterization to Tabulated data - Area vs. pressure, and Pressure control specification to Pressure at port A.

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

Vector of valve opening areas for the tabular area parameterization of the valve opening area. The vector elements must correspond one-to-one with the elements in the Pressure differential vector parameter. The elements must be in ascending order and must be greater than 0. The block employs linear interpolation between table data points.

Dependencies

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

Volumetric flow rate vector — Vector of volumetric flow rate for tabulated data parameterization
`[1e-09, 3.6e-05, 8.9e-05, .00015, .00023, .00031]`m^3/s (default) | 1-by-n vector

Vector of volumetric flow rate values for the tabular parameterization of the valve opening. This vector must have the same number of elements as the Pressure drop vector parameter. The vector elements must be in ascending order.

Dependencies

To enable this parameter, set Set pressure control to Constant and 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 either:

Set pressure control to Controlled.
Set pressure control to Constant and 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 either:

Set pressure control to Controlled.
Set pressure control to Constant and 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.

A smoothing factor of 0 corresponds to a linear function that is discontinuous at the set and maximum-area pressures. A smoothing factor of 1 corresponds to a nonlinear function that changes continuously throughout the entire function domain.

A smoothing factor between 0 and 1 corresponds to a continuous function with smooth nonlinear transitions at the set and maximum-area pressures.

Dependencies

To enable this parameter, set either:

Set pressure control to Controlled.
Set pressure control to Constant and Opening parameterization to Linear - Area vs. pressure.

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 cross-sectional area to a region of larger cross-sectional area. To capture the increase in pressure, select this parameter.

Dependencies

To enable this parameter, set either:

Set pressure control to Controlled.
Set pressure control to Constant and Opening parameterization to Linear - Area vs. pressure or Tabulated data - Area vs. pressure.

Opening dynamics — Whether to account for flow response to valve opening
`off` (default) | `on`

Whether to account for transient effects to the fluid system due to the valve opening. Selecting this parameter approximates the 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.

Faults

Pressure Relief Valve Area fault — Option to model opening area fault
`Add fault`

Option to model a valve area fault in the block. To add a fault, click the Add fault hyperlink. When a fault occurs, the valve area normally set by the opening parameterization is set based on the value specified in the Opening area when faulted parameter.

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

Faulted valve type. You can choose for the valve to seize when the valve is opened, closed, or at the area when the fault triggers.

Dependencies

To enable this parameter, click the Add fault hyperlink.

Extended Capabilities

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

Version History

Introduced in R2016a

expand all

R2024b: Model faults with the Simscape faults interface

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

R2024b: Model a controlled pressure relief valve

Set Set pressure control to Controlled to control the block set pressure with the signal at port Ps.

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 Relief Valve (TL)

Description

Pressure Control

Opening Parameterization

Opening Dynamics

Energy Balance

Faults

Predefined Parameterization

Examples

Reciprocal Actuator with Differential Cylinders

Ports

Input

Ps — Set pressure signal, Pa physical signal

Dependencies

Conserving

A — Liquid port thermal liquid

B — Liquid port thermal liquid

Parameters

Parameters

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

Dependencies

Opening parameterization — Method of modeling constant valve opening or closing Linear - Area vs. pressure (default) | Tabulated data - Area vs. pressure | Tabulated data - Volumetric flow rate vs. pressure

Dependencies

Pressure control specification — Method to evaluate pressure Pressure at port A (default) | Pressure differential

Dependencies

Set pressure (gauge) — Gauge pressure when opening mechanism triggers 0.1 MPa (default) | positive scalar

Dependencies

Set pressure differential — Minimum opening pressure differential 0 MPa (default) | nonnegative scalar

Dependencies

Pressure regulation range — Valve pressure range 0.15 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 shut position 1e-10 m^2 (default) | positive scalar

Dependencies

Pressure differential vector — Differential pressure values for tabular parameterization [0.2 : 0.2 : 1.2] MPa (default) | 1-by-n vector

Dependencies

Opening pressure (gauge) vector — Differential pressure values for tabular area parameterization [0.2 : 0.2 : 1.2] MPa (default) | 1-by-n vector

Dependencies

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

Dependencies

Volumetric flow rate vector — Vector of volumetric flow rate for tabulated data parameterization [1e-09, 3.6e-05, 8.9e-05, .00015, .00023, .00031]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 — Whether to account for pressure increase in area expansions off (default) | on

Dependencies

Opening dynamics — Whether to account for flow response to valve opening off (default) | on

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

Dependencies

Faults

Pressure Relief Valve Area fault — Option to model opening area fault Add fault

Opening area 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: Model a controlled pressure relief valve

R2023a: New Parameterization Options

See Also

Ps — Set pressure signal, Pa
physical signal

A — Liquid port
thermal liquid

B — Liquid port
thermal liquid

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

Opening parameterization — Method of modeling constant valve opening or closing
`Linear - Area vs. pressure` (default) | `Tabulated data - Area vs. pressure` | `Tabulated data - Volumetric flow rate vs. pressure`

Pressure control specification — Method to evaluate pressure
`Pressure at port A` (default) | `Pressure differential`

Set pressure (gauge) — Gauge pressure when opening mechanism triggers
`0.1` `MPa` (default) | positive scalar

Set pressure differential — Minimum opening pressure differential
`0` `MPa` (default) | nonnegative scalar

Pressure regulation range — Valve pressure range
`0.15` `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 shut position
`1e-10` `m^2` (default) | positive scalar

Pressure differential vector — Differential pressure values for tabular parameterization
`[0.2 : 0.2 : 1.2]` MPa (default) | 1-by-n vector

Opening pressure (gauge) vector — Differential pressure values for tabular area parameterization
`[0.2 : 0.2 : 1.2]` MPa (default) | 1-by-n vector

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

Volumetric flow rate vector — Vector of volumetric flow rate for tabulated data parameterization
`[1e-09, 3.6e-05, 8.9e-05, .00015, .00023, .00031]`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 — Whether to account for pressure increase in area expansions
`off` (default) | `on`

Opening dynamics — Whether to account for flow response to valve opening
`off` (default) | `on`

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

Pressure Relief Valve Area fault — Option to model opening area fault
`Add fault`

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

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