Orifice Pressure Dependent Area
Orifice with table-based pressure-dependent opening area
Description
Pressure vs Area
Optional Volumes
Equations
Variables
Connections
Parameters
The Orifice Pressure Dependent Area component models a sharp-edged orifice whose orifice varies with the pressure across the device.
The orifice area is computed as a function of the pressure difference between port A and port B from a data table containing values of pressure difference vs the corresponding orifice area. Based on the orifice area, the pressure vs flow rate relationships are derived by the formulation used in the Orifice component.
If A⁡−dp=−A⁡dp, then the symmetric parameter can be assigned true and only the first quadrant of the A vs dp curve needs to be defined in the table.
For this component, the orifice area must be specified as a function of the pressure difference in the form of a table. The following parameters allows users to specify the necessary data for this calculation.
Data Source: This parameter allows users to specify the nature of the source file for the Pressure vs. Area table. The available options are file, attachment, and inline.
file: Use this option to specify a source file (an Excel or a CSV file) located on the hard drive. Use the A⁡dP parameter to browse to and/or select the data file. The data file will not be attached to the MapleSim model.
attachment: Use this option to specify a data file (an Excel or a CSV file) that is attached to the MapleSim model. To be used as an attachment, data files must be attached to the MapleSim model and be categorized under Data Sets. The attached files in a MapleSim model can be viewed in the Attachments pane under the Data Sets section. For more information, see Attaching a File to a Model. If the required file is not already attached to the MapleSim model, use the A⁡dP parameter to attach a new file.
Note:
If the file option is used, subsequent changes to the source file will be incorporated into MapleSim simulations
If the attachment option is used, subsequent changes to the source file will not affect the version attached to the MapleSim model. To ensure updates to the source files are incorporated in the simulation, the file must be reattached.
The Data Generation App can be used to generate table data from mathematical functions using Maple code. For more information about MapleSim apps, see Opening MapleSim Apps and Templates.
inline: Use this option to directly specify the pressure vs. area relationship in the form of a table. In the A⁡dP parameter, enter an m×2 matrix. The first column must contain values of pressure difference and the second column must contain corresponding values of the area.
Note: To change the dimensions of table, right-click (Control-click for Mac®) the parameter field and select Edit Matrix Dimensions. In the Matrix Dimensions dialog, enter values for the number or rows and columns and then click OK.
Skip rows: This option allows users to specify the number of top rows to be ignored during the calculations. This option can be useful when the Excel file contains header information.
Smooth: The smooth option specifies how the data table is interpolated.
Pressure difference unit: This option specifies the unit of pressure used in the supplied data.
Area unit: This option specifies the unit of area used in the supplied data.
The boolean parameters Use volume A and Use volume B, when true, add optional volumes VA and VB to ports A and B, respectively. See Port Volumes for details.
If two orifices or valves are connected, enabling a volume at the common port reduces the the stiffness of the system and improves the solvability.
Ai=Interpolate1D⁡A⁡dP,{psymmetricpotherwise,smoothness,skipRows
Acs=max⁡minArea,AiareaScale
p=pA−pB=π8⁢ρ⁢ν⁢qCd2⁢Acs⁢π⁢Acs⁢16⁢q4π2⁢Acs2⁢ν4+ℜCr414
q=qA−qCAqA+qB−qCA−qCB=0
qCA={dVfAdtuseVolumeA0otherwiseqCB={dVfBdtuseVolumeB0otherwise
VfA=VA⁢1+pAEℓVfB=VB⁢1+pBEℓ
Name
Value
Units
Modelica ID
p
Pa
Pressure drop from A to B
q
m3s
Flow rate from port A to port B
qsummary
q⁢flowScaleSummary
Internal flow sensor
q_summary
dpsummary
p⁢pressScaleSummary
Internal pressure difference sensor
dp_summary
portA
Upstream hydraulic port
portB
Downstream hydraulic port
General Parameters
Default
Cd
710
Flow-discharge coefficient
ℜCr
12
Reynolds number at critical flow
ReCr
Area Vs. Pressure Parameters
symmetric
true
True (checked) the data for positive pressure difference used for both directions
Data source
inline
data source
datasourcemode
A⁡dP
[1]
data set
table
Skip rows
0
Number of rows to skip
skipRows
Smooth
linear
smoothness of table interpolation
smoothness
Pressure difference unit
kPa
Unit of pressure used in the data
pressUnit
Area unit
cm2
Unit of area used in the data
areaUnit
[1] 0,0;100,1;100,1
Volume Parameters
Use volume A
false
When true a hydraulic volume chamber is added to portA
useVolumeA
VA
1·10−6
m3
Volume of chamber A
Va
Use volume B
When true a hydraulic volume chamber is added to portB
useVolumeB
VB
Volume of chamber B
Vb
For more information see Port Volumes.
See Also
Hydraulics Library
Restrictions
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