|Compressible Fluid Flow Analysis for Network Piping Systems
Arrow provides unique modeling and analysis capabilities.
AFT Arrow has been used on thousands of applications ranging from chemical to petrochemical to power to pharmeceutical to facilities to aerospace and more. Systems include low pressure vent systems to high pressure relief systems with multiple sonic choking points.
AFT Arrow's flow solution engine is based on the Newton-Raphson matrix iteration method plus many proprietary solution methods developed by AFT over several years that increase solution speed and robustness. Unlike some other software that relies simpler, incompressible methods with compressible correction factors applied, AFT Arrow conducts a true and rigorous compressible analysis. Pipes are divided along their length and Arrow's solver switches between a length march and mach march depending on the solution progress. As well as the common adiabatic and isothermal approximations to real world gas flow, AFT Arrow can conduct a flow analysis with heat transfer and sonic choking. Arrow offers both ideal gas as well real gas modeling, ASME steam properties and, optionally, fluid property and mixtures modeling using the available Chempak Property Database.
While the following provides an outline of AFT Arrow's capabilites and how it used, it cannot replace first hand experience so that we invite you to request a free working demo to try yourself.
|AFT Arrow models are built in a graphical environment, displaying the model in a familiar schematic format. AFT Arrow models contain two constructs, pipes and junctions. Junction types included are;
- Tank (up to 25 pipes may be connected to each)
- Branch (up to 25 pipes may be connected to each)
- Compressor/Fan (as fixed specified flow or curve)
- Heat exchanger
- Assigned flow
- Assigned pressure
- Area change
- Tee/wye (uses the Idelchik and Miller loss relationships)
- One way valve (check valves and relief valves)
- Control valve (pressure reducing, pressure sustaining, constant pressure drop, flow - may be specified as fail open or close and fail upon reverse flow)
- Dead end
- Separator (for use with optional Chempak Fluid Property Database)
- General component (user defined component)
An AFT Arrow model is 'assembled' by dragging the junctions to be included onto the Workspace and connecting them with pipes (this can be done in any order and pipes and junctions can be added and deleted at any time). The resulting system schematic clearly displays the connective relationship between system components and pipe runs in the same way traditional schematics and diagrams do.
Each item on the Workspace is described through a Specifications window, opened by double-clicking on the object. In the case of pipes, for example, the diameter, length and roughness are specified (pipes may also be selected by material type and schedule from the built-in database and friction modeling may be selected from the drop down list, including absolute roughness, hydraulically smooth, frictionaless and others). In the case of compressors/fans, one selects between a fixed specified flow or modeling with a curve. If the latter is selected, data is input for the flow vs. head (or pressure) curve and Arrow calculates a curve fit to characterize the head curve. Compressors/fans may also be modeled as variable speed or as controlled flow or discharge pressure.
A summary of an object's specification may be seen by right-clicking on it to open the Inspection Window.
System lineup can be easily and quickly varied by opening and closing pipes and valves, compressor/fans turned on or off, control valves set to fail position.
AFT Arrow includes numerous tools for arranging and editing models that significantly reduce the time required to develop a model and change it.
|The Model Data window provides a tabular listing of the pipes' and junctions' input data. This is a great aid for some types of input review. For example, knowing that your pipe lengths are the range of a few feet to several tens or hundreds of feet, a scan down the pipe length column will quickly reveal an input value with an extra digit or two or a length unit mistakenly specified as miles instead of feet.
Double-clicking on an item within the Model Data window opens its Specifications window for editing.
|A tabular display of calculated results, the Output window is organized into General, Pipes and Junctions sections, which can be displayed all at once or individually. Additionally, the General and Junctions sections have tabbed sub-sections to quickly view specific categories. For example, the General section provides tabbed summaries for compressor/fans, valves and heat exchangers, it present in the model. The Junctions section has tabs to view the output results of all junctions as well as a tab for each type of junction in the model.
The Output provides extensive control by the user for such items as; what objects and parameters are displayed, units, order (including sorting), as well format controls for viewing and printing, all of which may be changed and the revised output viewed without re-running the model.
|Working in both an Input or Output mode, Visual Report displays selected input or output parameters with your model schematic. Visual Report can vary the color of pipes in the model according to a user defined color map based pressure, temperature, flow and many other parameters.
|Graphs of flow, pressure, temperature and many other parameters are quickly and easily generated by pipe or along a flowstream as well as system curves and compressor/fan vs. system curves.
|A powerful aspect of modeling software is the ability to change the system and study the effects - 'what if'. AFT Arrow's Scenario Manager raises this 'what if' capability to new levels by, first, allowing the user to define variations of a model and save them within one model file and two, automatically keeping common attributes between scenarios synchronized. Scenarios may vary by almost modeling parameters; pipe sizes, fluids, compressor/fan curves, valve settings, indeed, scenarios may differ by the elements present. For example, a variante of a model may have a planned future expansion. Changes in higher order scenarios are automatically passed downward to their 'children' for the parameters that are linked. Consider, for example, having a base scenario with several variants each with different pump curves. To change, say, the size of the pump discharge line on all variants, the Base can is selected, the change made and automatically passed to the 'children', both saving time and ensuring the variants remain synchronized in their common attributes.
|Fluids may be chosen from the standard AFT Arrow database of ~30 gases, user specified or from the optional Chempak Property Database add-in. With the Chempak add-in, almost 600 gases are available as well as the ability to assemble non-reacting mixtures and analyze dynamic mixtures resulting from intersecting flow streams.
|AFT Arrow provides extensive customization features including:
- Workspace appearance (colors, line widths, fonts, junction sizes and appearance, location of pipe numbers and names, notation)
- Preferred unit specification - english and SI units supported
- Apply design factors to pipe and junction losses, pump head and heat transfer
- Vary pipe thickness (with pipe diameter if desired)
Fluid, Component, Material Databases - AFT Arrow comes standard with a database of ~30 fluids and pipe dimensions and roughness for several types of steel, cast iron and PVC pipe, but you can readily add your own items. Work frequently with copper tubing? Input the data for the sizes you normally work with and they appear in drop down lists along with the standard database items. Fluids can be specified as a single point or with temperature dependent data and AFT Arrow does the work of curve fitting the data to an equation. Specified a compressor/fan that you will use again? Click on 'Add Component to Database' and it's readily available from a drop down list. In fact, you can easily compile catalogs of compressors/fans, valves, heat exchangers...virtually any kind of piping component to be quickly and easily selected within AFT Arrow. Better yet, database files can be shared either by copying between stand alone computers or across a network.
|Windows 95 and higher or NT 4.0 and higher
64 MB RAM minimum
800x600 display minimum
25 MB hard disk space
Stand-alone or network
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