Orifice with Pressure-dependent Flow - MapleSim Help

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Orifice with Pressure-dependent Flow

Orifice with pressure-dependent flow rate

 

Description

Pressure vs Flow Rate

Optional Volumes

Equations

Variables

Connections

Parameters

Description

The Orifice with Pressure-Dependent Flow component uses a user-supplied table to define the flow-rate for a given pressure drop. It is a general two-port component and not restricted to be an orifice but is labeled as such and given an appropriate icon for the user's convenience. A similar part is also available as a check valve and a relief valve.

The flow rate through the component 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 flow rate.

If qp=qp, then the symmetric parameter can be assigned true and only the first quadrant of the q vs p curve needs to be defined in the table.

Pressure vs Flow Rate

For this component, the flow rate 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. flow rate 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 AdP 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 AdP 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 AdP 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.

Flow unit: This option specifies the unit of flow rate used in the supplied data.

Optional Volumes

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 orfices or valves are connected, enabling a volume at the common port reduces the the stiffness of the system and improves the solvability.

Equations

p=pApB

q=qAqVA=qB+qVB={signpsymmetric1otherwiseInterpolate1DqdP,{psymmetricpotherwisepressUnit,2,smoothness,skipRows

qVA={dVfAdtuseVolumeA0otherwiseqVB={dVfBdtuseVolumeB0otherwise

VfA={VA1+pAEluseVolumeA0otherwiseVfB={VB1+pBEluseVolumeB0otherwise

Variables

Name

Value

Units

Description

Modelica ID

p

 

Pa

Pressure drop from A to B

p

q

 

m3s

Flow rate from port A to port B

q

qsummary

qflowScaleSummary

m3s

Internal flow sensor

q_summary

dpsummary

ppressScaleSummary

Pa

Internal pressure difference sensor

dp_summary

Connections

Name

Description

Modelica ID

portA

Upstream hydraulics port

portA

portB

Downstream hydraulic port

portB

Parameters

Flow Rate Vs. Pressure Parameters

Name

Default

Description

Modelica ID

symmetric

true

True (checked) the data for positive pressure difference used for both directions

symmetric

Data source

inline

data source

datasourcemode

qdP

100.,0.001

data set

table

Skip rows

0

Number of rows to skip

skipRows

Smooth

0

smoothness of table interpolation

smoothness

Pressure difference unit

kPa

Unit of pressure used in the data

pressUnit

flowUnit

cm2

Unit flow rate used in the data

flowUnit

Volume Parameters

Name

Default

Units

Description

Modelica ID

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

false

 

When true a hydraulic volume chamber is added to portB

useVolumeB

VB

1·10−6

m3

Volume of chamber B

Vb

For more information see Port Volumes.

See Also

Hydraulics Library

Restrictions