AFT Blog
If you have a system where there are several area changes throughout the piping, modeling every single area change and connecting pipe can become taxing and time consuming. Also, the more pipes and junctions that are in a model, the higher the complexity. With AFT software, it is very simple to include the area change losses in the pipes themselves! As seen in the Pipe Fittings and Losses screen shot below, there are four area change types that can be used and either abrupt or conical shapes can be modeled. The key to determining which expansion or contraction type to use...
AFT Fathom 8 has a new and improved method for predicting system pressures that involve laminar flow or non-Newtonian fluids. The Adjusted Turbulent K Factor (ATKF) method is used to apply corrections to pipes and components involving these special flows. The ATKF method can be enabled on the System Data tab in the System Properties window. Clicking on the question mark next to the ATKF method will access the AFT Fathom 8 Help Content that discusses the ATKF method in detail. In September 2012, Applied Flow Technology and DuPont published a technical article for the International Pump Users Symposium that discusses...
In AFT Impulse you can directly model a submerged pump. First, you will define your pump data exactly as you would normally, however you will only draw the discharge piping and not a suction piping. After doing this, you will check the box “Submerged Pump” at the bottom of the Pump Specifications Window. You now have an additional required input field. The “Suction Pressure” can be entered as a Head (HGL) or a Pressure. When entered as a Head (HGL) value, this value is the actual liquid elevation in the supply reservoir. When entered as a pressure, this is the actual...
The ability to specify default input parameters is a feature that is common to all AFT software products. Diameter, Friction Model, and Design Factors can be specified by default for pipes. Input properties for Junctions are specific to each junction type, so the only common default property is elevation. The default input options are found in “Parameter and Unit Preferences”. In general, this feature makes model building faster and more efficient. The user should, however, be aware of how this affects the “Status” of pipes and junctions. The “Status”, to which I am referring, is the green light to run the...
AFT Fathom 8 can be used to quickly and easily model multiple pump configurations with different pump speeds and impeller sizes. First, determine a particular pump curve to use from either a manufacturer’s pump curve or pump curve verification test data. Next, determine new pump curves for head and flow using the affinity laws considering either a change in pump speed or impeller size. The multiple pump curve data sets will then be entered for each particular pump configuration. In Figure 1 (click on the image to see it larger), there are a few pump configurations that have already been defined. ...
AFT Fathom has the ability to model heat transfer. The default mode (found in system properties) is “Constant Fluid Properties”. To avoid confusion in the default mode, several of the heat transfer input fields and option boxes are invisible or disabled until one of the following heat transfer modes are employed: Heat Transfer With Energy Balance (Single Fluid)Heat Transfer With Energy Balance (Multiple Fluids) Upon selecting one of these heat transfer modes, the user may notice an option box labeled “Balance Energy at Junction”; found at the lower left of the first tab in the properties window for the Assigned Pressure...
AFT Fathom provides a Three Way Valve which increases the Engineer’s capability to model system control. The Three Way Valve Properties Window shows the three connecting pipes in drop-down lists, which allows users to specify which pipe is the combined flow pipe, and which two are the split flow pipes. By entering the loss profile through each flow path, and then by selecting the actual percent open, Fathom will calculate the actual loss values for each flow path. Using the Three Way Valve in conjunction with the Goal Seek & Control module (GSC) increases the Engineer’s capability to model I&C logic...