Vacuum Pump
The Vacuum Pump node models the effective outlet pressure created by a vacuum pump device that is attached to the outlet.
Parameters
The Static pressure curve option defines a lumped curve — Linear, Static pressure curve data, or User defined.
Linear
For the Linear option, values or expressions should be specified for the Static pressure at no flow pnf and the Free delivery flow rate V0,fd.
The static pressure curve value is equal to the static pressure at no flow rate when V0 < 0 and equal to 0 when the flow rate is larger than the free delivery flow rate.
Static Pressure Curve Data
The Static pressure curve data option can be used to enter or load data under the Static Pressure Curve Data section below. The interpolation between points given in the Static Pressure Curve Data table is defined using the Interpolation function type list in the Static Pressure Curve Interpolation section.
User Defined
The User defined option can be used to enter a different value or expression. The flow rate across the selection where this boundary condition is applied is defined by phys_id.V0 where phys_id is the name (for example, phys_id is spf by default for this physics interface). In order to avoid unexpected behavior, the function used for the fan curve is the maximum of the user-defined function and 0.
Static Pressure Curve Data
This section displays when Static pressure curve data is selected as the Static pressure curve. In the table, values or expressions for the Flow rate and Static pressure curve should be specified. Alternatively, a text file can be imported by clicking the Load from file button () under the table.
Units
This section is available when Static pressure curve data is selected as the Static pressure curve. Units can be specified here for the Flow rate and Static pressure curve.
Static Pressure Curve Interpolation
This section is available when Static pressure curve data is selected as the Static pressure curve. The available options for the Interpolation function type are Linear, Piecewise cubic, and Cubic spline.
The extrapolation method always returns a constant value. In order to avoid problems with undefined data, the function used for the boundary condition is the maximum of the interpolated function and 0.
Location in user interface
Context Menus
Right click the physics interface and select Rotating Machinery>Vacuum Pump
Ribbon
Physics tab with the physics interface selected:
Boundaries>Rotating Machinery>Vacuum Pump
Vacuum Pump Boundary Condition
The Vacuum Pump feature computes the flow rate across the boundary selection. This feature is not designed to be used on disjoint selections. If the model includes several pumps on boundaries that are not connected, it is good practice to use different Vacuum Pump features with connected boundaries.