AFT Blog
In AFT Fathom and AFT Impulse, it is possible to model a submerged pump where a short and possibly frictionless suction pipe for the pump’s inlet does not need to be modeled. When modeling a submerged pump, there are two options available for specifying the system inlet boundary condition at the pump suction. As shown in Figure 1 below, the Submerged Pump’s Suction Pressure can either be specified as “Head (HGL)” or “Pressure”. Modeling a submerged pump is not the only time where the “Head (HGL)” or “Pressure” choices will arise. If an Exit Valve (i.e., a valve that discharges...
AFT Fathom can easily generate a pump and system curve for your piping system. Creating a pump and system curve for a simple system with a single flow path and no control features is an easy and typically well-understood process. However, as piping systems are quite complicated with lots of branch points, control features, and dynamic interactions, creating a useful system curve can quickly become a common source of confusion. This three-part blog series is going to help clarify concepts regarding pump and system curves to better understand them. This Part 1 blog will discuss the basics of what pump...
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...