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AFT Blog

Welcome to the Applied Flow Technology Blog where you will find the latest news and training on how to use AFT Fathom, AFT Arrow, AFT IMpulse, AFT xStream and other AFT software products.
Ben Keiser

When Should You Use Variable Pipe Resistance?

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...
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Applied Flow Technology

AFT Impulse Over the Years

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.   
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Trey Walters

AFT Impulse 20th Anniversary: A Perspective From the Original Impulse Developer

Twenty years ago today I was working desperately on putting the finishing touches on AFT Impulse 1.0. At the time, AFT was a pioneer in every sense of the word. AFT was the first and only company developing visual, drag-and-drop pipe flow modeling software for Microsoft Windows. And AFT Impulse was set to become the world's first visual waterhammer software for Windows. We already had orders for AFT Impulse before it was complete, such was the demand! The day-to-day demands of getting AFT going as a company was slowing down the completion of AFT Impulse. So I turned over the day-to-day tasks to the...
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Trey Walters

Inside, Outside, On Top Of and Behind the Incredible Hoover Dam

A little over 30 years ago I made a mistake. At the time I was a busy undergraduate student in mechanical engineering in California. Some students put together an official weekend trip for ME students to the Hoover Dam that included a special tour of the dam geared towards engineers and engineering students. I remember having tons of homework to do and decided not to go on the weekend trip. That was a mistake and I have regretted it ever since.

One outcome of that mistake is that I have rarely, if ever, missed another chance to go on a technical tour. Another outcome is that I have been trying to fit in a Hoover Dam visit ever since. I have been to or through Las Vegas (about 45 minutes from Hoover Dam) probably 30 times since then. But I could never find that half-day I needed to visit the dam with the other priorities I was trying to balance (usually involving my family that included four children). Until a couple of weeks ago.

Another twist for me involves the professor who taught me Statics (the study of stationary structures like dams). I was incredibly fortunate to take a Statics class when I was 19 years old from Howard Eberhart. He was an outstanding teacher and memorable character. Professor Eberhart towered over most of us students at 6' 4" (1.93 m) in height. I will never forget his steely blue eyes, bald head, and deep, gravelly voice proclaiming (for the hundredth time), "It is all...simple...statics!". 

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Erin Onat

A Clever Way to Mitigate Waterhammer During a Valve Closure

One of the most common causes of waterhammer in pipelines is a valve closure. As the valve closes, the flowing liquid is forced to stop, resulting in a transfer of kinetic energy to potential energy, which ultimately causes a pressure increase. If this increase in pressure is large enough, extremely severe damage can result in the pipeline. Engineers frequently mitigate this waterhammer by selecting a valve that closes slowly enough to prevent the pressures from getting too high. However, a valve that closes too slowly can cause problems elsewhere in the pipeline or result in other undesirable outcomes in the process....
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Trey Walters

How Does AFT Software Make the World a Safer Place?

 

Safety is a primary consideration in engineering design. Safety for people is always paramount. Safety for the environment is an ever-growing focus of engineers. Any engineer worth the name would feel devastated if their engineering effort failed for some reason to protect people and the environment. One of the things engineers rely on to make system designs and operations safer are analytical tools like those developed by Applied Flow Technology (AFT). How does AFT software make the world a safer place?

The first and most obvious way that AFT software makes the world safer is that our software products help engineers test their designs and operations on their computers where the impact of failure is eliminated. While this is invaluable, it is a bit abstract. So let's get more specific and highlight some applications where safety is impacted.

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Trey Walters

Should Engineers Always Perform Waterhammer Analysis of New Pipe Systems? Part 2

Two years ago this month I wrote this blog article: "Should Engineers Always Perform Waterhammer Analysis of New Pipe Systems?". This was a popular blog. It was written from the fluid dynamic engineer's perspective. Last month I was teaching an AFT Impulse training seminar and this same question came up during the class from an astute attendee. However, the question came more from a pipe stress engineer's perspective. And I realized that the answer to the question is not necessarily the same for a pipe stress engineer. Thus came the idea to write a Part 2 to the previous blog. A fluid...
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