AFT Impulse FAQ's

Yes, AFT Impulse uses the Discrete Vapor Cavity Model or Discrete Gas Cavity Model.

No, AFT Impulse only models transients in liquid systems.

Yes. Pumps can be modeled as a prescribed speed transient or the speed can be calculated based on pump inertial characteristics.

Yes, positive displacement pumps can be modeled as steady operation with periodic flow or during startups and shutdowns.

Yes.

Yes, AFT Impulse offers Power Law and Bingham Plastic non-newtonian fluid models, and offers the Duffy method and Brecht & Heller for pulp and paper system modeling.

Impulse can model partially filled pipes at the end of a flow path or run. This capability is primarily intended to handle the situation where a supply riser to a cooling tower or condenser, for example, partially drains when the system is not in operation.

Whereas the Output Control window allows you specify units for all parameters, when in the Output window viewing results you can quickly change the units for parameters in the tabular displays by double-clicking the column header.

Open the Visual Report Control window, change to the Show Selected Pipes/Jcts folder tab, and use the provided features to specify which pipes and junctions should display data and which should not.

Open the Output Control window from the Analysis menu, change to the Show Selected Pipes/Jcts folder tab, and select the pipes and or junctions you want to display.

Open the Output Control window from the Analysis menu, change to the Format & Action folder tab, and choose to select the Transfer Results to Initial When Done, Transfer Valve States When Done, and Save Model When Results are Transferred options.

Yes, the Scenario Manager lets you create dependent design cases where changes are inherited by children.

Multiple models can be run sequentially using the Batch Run feature.

See Custom Database Overview in the help file.

See Network Database Overview.

Yes, users can assign an elevation profiles to individual pipes.

Yes, AFT Impulse allows you to include these as "design alerts". Design alerts can be cross-plotted against pressure profiles.

AFT Impulse offers a standard set of properties for common fluids in the AFT Standard Fluids database. It also offers the NIST REFPROP database included with all AFT applications. Users can also utilize the optional Chempack add-on database which is a chemical property database of up to 700 fluids with mixing capability. Use the database as a stand-alone application with the Chempak Viewer or access the database from within Microsoft Excel with the Chempak Add-in.

The steady-state solver in AFT Impulse uses the same method as AFT Fathom. However, its purpose is different. AFT Fathom is a general purpose steady-state modeling tool. On the other hand, AFT Impulse uses steady-state only as it relates to waterhammer. Thus some capabilities found in AFT Fathom do not exist or are more limited in AFT Impulse. The most important differences are as follows: AFT Impulse does not model heat transfer. It does not have junctions for static elements like elbows, orifices, heat exchangers, etc., although these can still be modeled in AFT Impulse but through other methods such as Additional Losses in pipes or as General Components. AFT Impulse does not offer polynomial resistance curves except for General Components. AFT Impulse does not offer graphing of pump and system curves, which only have meaning for steady-state.

Open the Junction Properties window, click the Optional folder tab, and then click the Change Icon button.

No, icons are in a resource file that cannot be edited by the user. 

There are three ways to enable or disable the Highlight feature. The first is toggling the option on the Options menu. The second is pressing the F2 function key while in a Pipe and Junction Specifications window. The third is double-clicking the anywhere in the Pipe and Junction Specifications window.

Select the pipe or pipes and choose the Reverse Direction feature on the Arrange menu.

 Use the Segment Pipe tool found on the Arrange Menu.

Use the Merge feature on the File menu to merge models together.

The Global Pipe Edit and Global Junction Edit windows offer tremendous power and flexibility in changing all or parts of your model input all at once. See Global Pipe Edit and Global Junction Edit topics for more information.

Open the pipe or junction specifications window, click the Optional folder tab, and check or clear the check boxes for showing the number or name. This will affect the current pipe or junction. You can set the default behavior in the Workspace Preferences window available on the Options menu.

You can use the Global Edit windows to change the current model settings for all pipes or junctions or only selected ones. See the Global Pipe Edit or Global Junction Edit window for more information.

Use the Find feature to quickly find a pipe or junction.

If you hold down the CTRL key when completing the pipe drawing (just before releasing the mouse button), the Pipe Drawing tool remains active, and you can draw a series of pipes without returning to the Toolbox each time. If you double-click the Pipe Drawing tool it remains active until you click it again a single time. This allows you to draw a series of pipes without returning to the Toolbox each time.

In the Model Data tabular displays double-click on a row to launch that pipe/junction’s properties window.

The preferred units can be chosen when the software is first opened by selecting unit sets in the Startup window. Alternatively, this can be done by going to the Tools menu and opening User Options.  On the left pane select Preferred Units under the Unit System header. You can then select a commonly used set of units, or change individual unit types.