Orifice (IL)

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A hole of constant or variable area in an isothermal fluid network.

blockType: EngeeFluids.IsothermalLiquid.Orifices.LocalRestriction

Orifice (IL)

Path in the library:

/Physical Modeling/Fluids/Isothermal Liquid/Valves & Orifices/Orifices/Orifice (IL)

Variable Orifice (IL)

Path in the library:

/Physical Modeling/Fluids/Isothermal Liquid/Valves & Orifices/Orifices/Variable Orifice (IL)

Description

Block Orifice (IL) simulates a flow through a local constraint with a constant or variable opening area. For variable openings, the control element connected to the S port sets the opening position. The change in the opening area is set as linear or according to the table.

local restriction (il) 1 s

The block equations determine the mass flow through the pressure difference between ports A and B:

This equation of conservation of mass implies an increase in velocity with a decrease in area and a decrease in velocity when the flow goes into a larger area. According to the Bernoulli principle, this change in velocity leads to the appearance of an area of low pressure in the orifice and increased pressure in the expansion zone. The resulting pressure increase, called pressure recovery, depends on the flow rate of the orifice and the ratio of the orifice and port areas.

Permanent openings

For permanent holes, the hole area is it does not change during the simulation.

constant hole area

If for the parameter Orifice parameterization the value is set Orifice area, then the block calculates the mass flow rate as:

where

— expense ratio Discharge coefficient;
— instantaneous open hole area;
— cross-sectional area of ports A and B;
— the average density of the liquid.

Pressure losses and They are calculated the same way for permanent and variable openings.

This is an approximation for and the block Local Restriction (IL) They are the same.

Table dependence of volume flow on pressure drop_

If for the parameter Orifice parameterization the value is set Tabulated data - Volumetric flow rate vs. pressure drop, then the block calculates the volumetric flow rate based on the tabular differential pressure values which you can provide. If you provide only non-negative values for the volume flow and differential pressure vectors, the block extrapolates the table to negative values. The volume flow is interpolated from this expanded table.

If the parameters are Volumetric flow rate vector and Pressure drop vector They contain both negative and positive values, but do not contain 0. The block inserts the origin into vectors to ensure that the valve does not have a non-zero flow rate with a pressure drop of 0, which is not physical.

Variable openings

For variable openings, if for the parameter Opening orientation the value is set Positive control member displacement opens orifice, that hole opens when the signal on port S is positive. If for the parameter Opening orientation the value is set Negative control member displacement opens orifice, that hole opens when the signal on port S is negative. If the signal is positive in both cases, then the opening of the hole is determined by the magnitude of the signal.

The linear dependence of the hole area on the position of the control element

If for the parameter Orifice parameterization the value is set Linear - Area vs. control member position, then the area of the hole depends on the position of the control element and the ratio of the hole area to the maximum position of the control element.:

where

— the position of the control element when the opening is completely closed;
— parameter value Control member travel between closed and open orifice;
— parameter value Maximum orifice area;
— parameter value Leakage area;
— parameter value Opening orientation.

When the hole is in a nearly open or nearly closed position in linear parameterization, you can maintain the numerical stability of the simulation by adjusting the parameter Smoothing factor. If the parameter Smoothing factor is not equal to zero, the block smoothly saturates the area of the hole between and .

The mass flow rate is determined by the equation:

where — parameter value Cross-sectional area at ports A and B.

Table dependence of the hole area on the position of the control element_

If for the parameter Orifice parameterization the value is set Tabulated data - Area vs. control member position, then the area of the hole It is interpolated from the tabular values of the hole area and the position of the control element. which you can provide. As with parameterization Linear - Area vs. control member position, the mass flow rate is determined by the equation:

where

— This is:
- — the last element of the vector Orifice area vector if the hole is larger than the maximum specified hole;
- — the first element of the vector Orifice area vector if the hole is smaller than the minimum;
- if the calculated area is between the limits of Orifice area vector;
— the function of the position of the control element coming to the port S. The block performs queries between data points using linear interpolation and uses the closest extrapolation for points beyond the boundaries of the table.

Table dependence of the volume flow on the position of the control element and the pressure drop_

If for the parameter Orifice parameterization the value is set Tabulated data - Volumetric flow rate vs. control member position and pressure drop, then the unit interpolates the volumetric flow rate directly from the volumetric flow table provided by the user, which is based on the position of the control element and the pressure drop through the hole. The block performs queries between data points using linear interpolation and uses linear extrapolation for points beyond the boundaries of the table.

These data may include negative pressure drops and negative opening values. If a negative pressure drop is included in the dataset, the volumetric flow rate will change direction. However, for negative opening values, the flow rate will remain unchanged.

If the parameter Pressure drop vector, dp does not contain 0, but the parameter Volumetric flow rate table, q(s,dp) – the corresponding column of zeros, the block inserts them so that the valve does not have a non-zero flow rate when the pressure drop is 0, which is non-physical.

Pressure loss

Pressure loss describes a decrease in pressure in a valve due to a decrease in area. The pressure loss term, , calculated as:

Pressure recovery describes a positive pressure change in the valve due to an increase in area. If you do not want to record this increase in pressure, uncheck the box. Pressure recovery. In this case it will be equal to 1.

Critical pressure

Critical pressure drop — this is the pressure drop associated with the critical Reynolds number, , which is the transition point between laminar and turbulent fluid flows:

Ports

Conserving

# A — Isothermal liquid port
Isothermal liquid

Details

The port of the isothermal liquid corresponds to the Input or output of the hole. This unit has no internal orientation.

Program usage name

port_a

# B — Isothermal liquid port
Isothermal liquid

Details

The port of the isothermal liquid corresponds to the Input or output of the hole. This unit has no internal orientation.

Program usage name

port_b

Input

# S — moving the control element
scalar

Details

The input port for moving the control element, specifying the opening of the hole.

Dependencies

To use this port, set the parameter Orifice type value Variable.

Data types	`Float64`
Complex numbers support	I don’t

Parameters

Main

# Orifice type — hole type
Constant | Variable

Details

The type of hole determined by the area of the hole. If the value is set to Variable, then the area of the hole varies depending on the input signal coming to port S.

Values	`Constant` \| `Variable`
Default value	`—`
Program usage name	`type`
Evaluatable	No

# Orifice parameterization — the method of calculating the constant area of the hole
Orifice area | Tabulated data - Volumetric flow rate vs. pressure drop

Details

The method of calculating the area of the hole during modeling:

Orifice area — the specified area does not change during the modeling process.
Tabulated data - Volumetric flow rate vs. pressure drop — the set area remains constant, but the volume flow through the hole may vary. Its value is interpolated directly from the parameter values. Volumetric flow rate vector and Pressure drop vector.

Dependencies

To use this parameter, set for the parameter Orifice type meaning Constant.

Values	`Orifice area` \| `Tabulated data - Volumetric flow rate vs. pressure drop`
Default value	`Orifice area`
Program usage name	`fixed_restriction_parameterization`
Evaluatable	No

# Orifice parameterization — the method of calculating the variable area of the hole
Linear - Area vs. control member position | Tabulated data - Area vs. control member position | Tabulated data - Volumetric flow rate vs. control member position and pressure drop

Details

The method of calculating the area of the hole during modeling:

Linear - Area vs. control member position — the area is determined linearly depending on the position of the control element in relation to a fully open or fully closed hole. The position is set by a changing signal on the S port.
Tabulated data - Area vs. control member position — the area of the hole is interpolated from Control member position vector and Orifice area vector based on the position of the control element received via the S port.
Tabulated data - Volumetric flow rate vs. control member position and pressure drop — volume flow is directly interpolated from the parameter values provided by the user Control member position vector, Pressure drop vector and Volumetric flow rate table, q(s,dp) based on the position of the control element received through port S and the pressure drop through ports A and B.

Dependencies

To use this parameter, set for the parameter Orifice type meaning Variable.

Values	`Linear - Area vs. control member position` \| `Tabulated data - Area vs. control member position` \| `Tabulated data - Volumetric flow rate vs. control member position and pressure drop`
Default value	`Linear - Area vs. control member position`
Program usage name	`variable_restriction_parameterization`
Evaluatable	No

# Orifice area — hole area
m^2 | cm^2 | ft^2 | in^2 | km^2 | mi^2 | mm^2 | um^2 | yd^2

Details

The cross-sectional area of the hole.

Dependencies

To use this parameter, set for the parameter Orifice type meaning Constant, and for Orifice parameterization — Orifice area.

Units	`m^2` \| `cm^2` \| `ft^2` \| `in^2` \| `km^2` \| `mi^2` \| `mm^2` \| `um^2` \| `yd^2`
Default value	`1e-3 m^2`
Program usage name	`fixed_restriction_area`
Evaluatable	Yes

# Pressure drop vector — vector of differential pressure values for tabular parameterization
Pa | GPa | MPa | atm | bar | kPa | ksi | psi | uPa | kbar

Details

Vector of differential pressure values for tabular parameterization of volume flow. The values in this vector correspond one-to-one to the values in the vector parameter Pressure drop vector. The values of the pressure drop vector are listed in ascending order. The volume flow is interpolated directly from Volumetric flow rate vector, which depends on the parameter Pressure drop vector.

Dependencies

To use this parameter, set for the parameter Orifice type meaning Constant, and for Orifice parameterization — Tabulated data - Volumetric flow rate vs. pressure drop.

Units	`Pa` \| `GPa` \| `MPa` \| `atm` \| `bar` \| `kPa` \| `ksi` \| `psi` \| `uPa` \| `kbar`
Default value	`[-4.0, -3.0, -2.0, -1.0, -0.5, 0.0, 0.5, 1.0, 2.0, 3.0, 4.0] MPa`
Program usage name	`delta_p_fixed_vector_1D`
Evaluatable	Yes

# Volumetric flow rate vector — vector of volume flow values
m^3/s | m^3/h | cm^3/s | mm^3/s | ft^3/s | lpm | l/s | gpm | gal/s | gal/h

Details

Vector of volume flow values for tabular parameterization of volume flow. The values in this vector correspond one-to-one to the values in Pressure drop vector. The volume flow is interpolated directly from Volumetric flow rate vector, which depends on the parameter Pressure drop vector.

Dependencies

To use this parameter, set for the parameter Orifice type meaning Constant, and for Orifice parameterization — Tabulated data - Volumetric flow rate vs. pressure drop.

Units	`m^3/s` \| `m^3/h` \| `cm^3/s` \| `mm^3/s` \| `ft^3/s` \| `lpm` \| `l/s` \| `gpm` \| `gal/s` \| `gal/h`
Default value	`[-2.44, -2.12, -1.68, -1.22, -0.84, 0, 0.85, 1.21, 1.7, 2.09, 2.41]* 1e-3 m^3/s`
Program usage name	`Vdot_fixed_vector_1D`
Evaluatable	Yes

# Control member position at closed orifice — displacement of the control element
m | cm | ft | in | km | mi | mm | um | yd

Details

The initial displacement of the control element when the variable opening is fully closed.

Dependencies

To use this parameter, set for the parameter Orifice type meaning Variable.

Units	`m` \| `cm` \| `ft` \| `in` \| `km` \| `mi` \| `mm` \| `um` \| `yd`
Default value	`0.0 m`
Program usage name	`min_control_displacement`
Evaluatable	Yes

# Control member travel between closed and open orifice — maximum stroke of the control element
m | cm | ft | in | km | mi | mm | um | yd

Details

The maximum distance that the control element passes between the closed and open openings. The hole is fully open when the sum of the position of the control element when the hole is closed and the stroke of the control element between the closed and open holes.

Dependencies

To use this parameter, set for the parameter Orifice type meaning Variable, and for Orifice parameterization — Linear - Area vs. control member position.

Units	`m` \| `cm` \| `ft` \| `in` \| `km` \| `mi` \| `mm` \| `um` \| `yd`
Default value	`5e-3 m`
Program usage name	`delta_control_displacement`
Evaluatable	Yes

# Opening orientation — the direction of movement of the element opening the hole
Positive control member displacement opens orifice | Negative control member displacement opens orifice

Details

The direction of movement of the element opening the variable hole. A positive orientation means that a positive signal on S opens the hole. A negative direction means that a negative signal on S opens the hole.

Dependencies

To use this parameter, set for the parameter Orifice type meaning Variable.

Values	`Positive control member displacement opens orifice` \| `Negative control member displacement opens orifice`
Default value	`Positive control member displacement opens orifice`
Program usage name	`opening_orientation`
Evaluatable	No

# Maximum orifice area — maximum opening area of the hole
m^2 | cm^2 | ft^2 | in^2 | km^2 | mi^2 | mm^2 | um^2 | yd^2

Details

The maximum area of the hole during the simulation. When using Tabulated data - Area vs. control member position, the maximum area of the hole is the last element of the vector Orifice area vector.

Dependencies

To use this parameter, set for the parameter Orifice type meaning Variable, and for Orifice parameterization — Linear - Area vs. control member position.

Units	`m^2` \| `cm^2` \| `ft^2` \| `in^2` \| `km^2` \| `mi^2` \| `mm^2` \| `um^2` \| `yd^2`
Default value	`1e-4 m^2`
Program usage name	`max_restriction_area`
Evaluatable	Yes

# Leakage area — the gap area in the fully closed position
m^2 | cm^2 | ft^2 | in^2 | km^2 | mi^2 | mm^2 | um^2 | yd^2

Details

The sum of all clearances when the valve is in the fully closed position. Any area less than this value is maintained at the level of the specified leakage area. This parameter contributes to numerical stability by maintaining continuity of flow.

Dependencies

To use this parameter, set for the parameter Orifice type meaning Variable, and for Orifice parameterization — Linear - Area vs. control member position.

Units	`m^2` \| `cm^2` \| `ft^2` \| `in^2` \| `km^2` \| `mi^2` \| `mm^2` \| `um^2` \| `yd^2`
Default value	`1e-10 m^2`
Program usage name	`leakage_area`
Evaluatable	Yes

# Control member position vector — vector of positions of control elements
m | cm | ft | in | km | mi | mm | um | yd

Details

Vector of positions of control elements for tabular parameterization of volume flow. The one-to-one position vector of the control elements corresponds to the vector of the areas Orifice area vector. The values are listed in ascending order, and the first element must be `0'. Linear interpolation is used between the data points in the table.

Dependencies

To use this parameter, set for the parameter Orifice type meaning Variable, and for Orifice parameterization — Tabulated data - Area vs. control member position.

Units	`m` \| `cm` \| `ft` \| `in` \| `km` \| `mi` \| `mm` \| `um` \| `yd`
Default value	`[0.0, 2e-3, 4e-3, 7e-3, 1.7e-2] m`
Program usage name	`control_displacement_vector_1D`
Evaluatable	Yes

# Orifice area vector — vector of values of the hole opening area
m^2 | cm^2 | ft^2 | in^2 | km^2 | mi^2 | mm^2 | um^2 | yd^2

Details

A vector of hole area values for tabular parameterization of the hole area. The values in this vector are correlated one-to-one with the elements in Control member position vector. If the vector increases, then the first element of this vector is the leakage area of the hole, and the last element is the maximum area of the hole. If the vector is decreasing, then the first element of this vector is the maximum area of the hole, and the last element is the area of the leak. The opening area of the hole is interpolated from the vector of the hole area, which depends on the vector Control member position vector.

Dependencies

To use this parameter, set for the parameter Orifice type meaning Variable, and for Orifice parameterization — Tabulated data - Area vs. control member position.

Units	`m^2` \| `cm^2` \| `ft^2` \| `in^2` \| `km^2` \| `mi^2` \| `mm^2` \| `um^2` \| `yd^2`
Default value	`[1e-9, 2.0352e-7, 4.0736e-5, 1.1438e-4, 3.4356e-4] m^2`
Program usage name	`restriction_area_vector_1D`
Evaluatable	Yes

# Cross-sectional area at ports A and B — the area at the entrance or exit of the hole
m^2 | cm^2 | ft^2 | in^2 | km^2 | mi^2 | mm^2 | um^2 | yd^2

Details

The cross-sectional area at the inlet and outlet of the holes A and B. This area is used in the pressure flow rate equation, which determines the mass flow through the hole.

Dependencies

To use this parameter, set:

Orifice type in the value Variable and Orifice parameterization in the value Linear - Area vs. control member position or Tabulated data - Area vs. control member position.
Orifice type in the value Constant and Orifice parameterization in the value Orifice area.

Units	`m^2` \| `cm^2` \| `ft^2` \| `in^2` \| `km^2` \| `mi^2` \| `mm^2` \| `um^2` \| `yd^2`
Default value	`Inf m^2`
Program usage name	`port_area`
Evaluatable	Yes

# Discharge coefficient — expense ratio

Details

The correction factor is the ratio of the actual mass flow to the theoretical mass flow through the hole.

Default value	`0.64`
Program usage name	`C_d`
Evaluatable	Yes

# Critical Reynolds number — upper limit of the Reynolds number for laminar flow

Details

The upper limit of the Reynolds number for laminar flow through the hole.

Dependencies

To use this parameter, set:

Orifice type in the value Variable and Orifice parameterization in the value Linear - Area vs. control member position or Tabulated data - Area vs. control member position.
Orifice type in the value Constant and Orifice parameterization in the value Orifice area.

Default value	`150`
Program usage name	`Re_critical`
Evaluatable	Yes

# Smoothing factor — numerical smoothing factor

Details

A continuous smoothing coefficient that introduces a layer of gradual change in the flow response when the hole is in an almost open or almost closed position. Set a non-zero value less than one to increase the stability of the simulation in these modes.

Default value	`0.01`
Program usage name	`smoothing_factor`
Evaluatable	Yes

# Pressure recovery — should the pressure increase be taken into account when expanding the area

Details

Should the pressure increase be taken into account when liquid flows from an area with a smaller cross-sectional area to an area with a larger cross-sectional area.

If you uncheck the box Pressure recovery this increase in pressure is not taken into account.

Dependencies

To use this parameter, set:

Orifice type in the value Variable and Orifice parameterization in the value Linear - Area vs. control member position or Tabulated data - Area vs. control member position.
Orifice type in the value Constant and Orifice parameterization in the value Orifice area.

Default value	`false (switched off)`
Program usage name	`pressure_recovery`
Evaluatable	No

# Control member position vector, s — position vector of the control element
m | cm | ft | in | km | mi | mm | um | yd

Details

Vector of positions of control elements for tabular parameterization of volume flow. The one-to-one position vector of the control elements corresponds to the pressure drop vector Pressure drop vector, dp, for the two-dimensional dependence of the volume flow table Volumetric flow rate table, q(s,dp). A positive displacement corresponds to the opening of the valve. The values are listed in ascending order, and the first element should be 0. Linear interpolation is used between the data points in the table.

Dependencies

To use this parameter, set for the parameter Orifice type meaning Variable, and for Orifice parameterization — Tabulated data - Volumetric flow rate vs. control member position and pressure drop.

Units	`m` \| `cm` \| `ft` \| `in` \| `km` \| `mi` \| `mm` \| `um` \| `yd`
Default value	`[0.0, 2e-3, 4e-3, 7e-3, 1.7e-2] m`
Program usage name	`control_displacement_vector_2D`
Evaluatable	Yes

# Pressure drop vector, dp — vector of pressure drop values
Pa | GPa | MPa | atm | bar | kPa | ksi | psi | uPa | kbar

Details

Vector of differential pressure values for tabular parameterization of volume flow. The one-to-one pressure drop vector corresponds to the position vector of the control element Control member position vector, s for a two-dimensional dependence of the volume flow table Volumetric flow rate table, q(s,dp). The values are listed in ascending order and must be greater than 0. Linear interpolation is used between the data points in the table.

Dependencies

Units	`Pa` \| `GPa` \| `MPa` \| `atm` \| `bar` \| `kPa` \| `ksi` \| `psi` \| `uPa` \| `kbar`
Default value	`[0.3, 0.5, 0.7] MPa`
Program usage name	`delta_p_vector_2D`
Evaluatable	Yes

# Volumetric flow rate table, q(s,dp) — table of volume flow values
m^3/s | m^3/h | cm^3/s | mm^3/s | ft^3/s | lpm | l/s | gpm | gal/s | gal/h

Details

The matrix on volumetric flow rates based on independent values of the pressure drop and the position of the control element. Values on — the sizes of the corresponding vectors:

— the number of elements in the pressure drop vector Pressure drop vector, dp.
— the number of elements in the position vector of the control element Control member position vector, s.

Dependencies

Units	`m^3/s` \| `m^3/h` \| `cm^3/s` \| `mm^3/s` \| `ft^3/s` \| `lpm` \| `l/s` \| `gpm` \| `gal/s` \| `gal/h`
Default value	`[1.7e-05 2e-05 2.6e-05; 0.0035 0.0045 0.0053; 0.7 0.9 1.06; 1.96 2.5 3.0; 6.0 7.7 9.13]*1e-3 m^3/s`
Program usage name	`Vdot_matrix_2D`
Evaluatable	Yes