AFT Blog

Have you ever finished running an AFT Impulse model and then received the following Warning message shown in Figure 1 and then wondered what it means? During a waterhammer analysis, the flowrates are constantly changing all throughout the system, therefore, the velocities and Reynold's numbers are also constantly changing.  The friction factors will also be constantly changing during the transient.  By default, AFT Impulse will use the friction factors that are obtained during the steady-state analysis and then use the same friction factors during the transient and they will be assumed to remain constant. Since it is possible for the flowrates...

November 21, 2016, marks AFT Impulse's 20th anniversary! Below is a timeline that captures a few of the most significant ways it has evolved from Version 1.0 to Version 6.0.   

They say that time is of the essence, and as engineers, that couldn’t ring truer! AFT pipe flow software is there to help engineers save time by more safely, efficiently, and rapidly designing and analyzing their piping systems. AFT Impulse, Applied Flow Technology’s waterhammer tool, helps engineers analyze transient incompressible flow behavior that can cause potentially detrimental pressure surges. It uses the Method of Characteristics, which requires the pipes to be sectioned using a Characteristic Grid. In this Characteristic Grid, all of the pipes are broken into an integer number of section lengths, and pressure waves are assumed to propagate through...

Previously, we talked about the Graph Guide, creating Stacked graphs and Dual-Y graphs, and visualizing the results using Animated graphs. This final installment will focus on the various ways to format graphs so they are exactly how you want them to look. In general, there are several ways to set the formatting for the various parts and regions of a graph. I will start with the model we made in the previous blog – the AFT Impulse model, ‘Pump Startup With Event Transient.imp’, which is installed in the Examples folder. Many of the formatting options are gathered together on the Formatting...

You may have heard, “there is never enough money to do it right the first time, but there’s always enough money to fix it after it’s broke." As engineers and project managers it is our responsibility to provide safe solutions to complex problems in an economy that typically gives jobs to the lowest bidder. Often these two ideas, safety and cost, seem to be at odds with each other. The more time put into insuring safety can rise costs to an unviable level and often times a “sweet spot” must be reached. One cost saving measure in piping design is to...

Users and potential users of AFT software frequently ask how they can expedite the model input process so that they can get the results they need as rapidly as they need. I’m pleased to report that AFT software has an abundance of features that make the model input process tremendously efficient: global pipe and junction editing, copying input data from other pipes and junctions, and finally, importing data using the Excel Change Data parameters spreadsheet (which is what we are discussing in this blog). The Excel Change Data feature works by importing data from an Excel spreadsheet populated according to a...

Previously, we talked about the Graph Guide and how to create Stacked Graphs and Dual-Y graphs. With AFT Impulse and with AFT Fathom’s XTS module, a great way to see how parameters change over time is through animated graphs. For the purpose of continuity, I am going to again start with the AFT Impulse model, ‘Pump Startup With Event Transient.imp’, which is installed in the Examples folder, and use the ‘One Pump Start With One Running’ scenario. In the previous blogs, we used a Stacked Graph and a Dual-Y Axis Graph to examine the pressures and flows at two valves (J6...