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Trey Walters

Taking the Pulse of Fluid Systems: Introducing the New AFT Impulse PFA Module

Pulsation in fluid systems...Is it steady-state or is it transient? Well, it is both. Kind of. Pulsation causes periodic transients that are regular in nature and thus considered steady-state. It can be called "steady-state pulsation".

The problem is not whether pulsation is steady-state or transient. It is whether the frequencies that are excited by the pulsation are at or near the acoustic resonant frequencies of the fluid system. If so, there can be problems. API 674 defines the allowable pulsation limits for positive displacement pumps.

AFT will soon release the new PFA module for AFT Impulse. PFA stands for Pulsation Frequency Analysis. This new module will help engineers predict, understand and avoid resonant frequencies related to the fluid acoustics. It will also help engineers assess whether their system is in compliance with API 674.

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Trey Walters

America's Wacky New President...and Technology

I am not a political commentator. But anyone not living in a cave has to admit that the past year of American politics was just plain wacky. For those of you for whom English is not your first language, "wacky" is a word that basically means (by my personal definition) "strange, highly unusual and a bit crazy". Which also applies to Donald Trump.

Donald Trump was sworn in as the 45th American President two days ago on Friday, January 20th. I spent Friday and the rest of this weekend pondering this and what it might mean for those who work in technology. 

What actually happens under President Trump is anyone's guess at this point. Leaving aside (to the political commentators) all of the wacky things President Trump has said, I am going to take some time here to speculate on what it means for technology. I am talking of technology here in a broad sense, and not the ridiculously narrow sense one often sees it portrayed - as if Silicon Valley technology is the only technology which is important.

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Trey Walters
Dear Michael: I will tread carefully in the area of politics and just say that there are many places in the world where similar t... Read More
Monday, 06 February 2017 16:17
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Dave Miller

Tolerable Convergence

Trying to design and analyze piping systems can be a complicated, and difficult task for engineers. This was especially true before the advent of easily accessible computer technology. Hand calculations required hundreds of hours of painstaking work, by entire teams of people. Great care had to be taken to ensure the reliability and accuracy of the results. Human beings do make mistakes, after all.

In today’s engineering world, there are a multitude of computer tools designed to make the design process simpler, faster, and more reliable, such as AFT’s family of analysis products. AFT products revolve around graphically based, drag and drop interfaces that makes creating a computer model of piping systems quick, and easy. Being able to create simulation models with little effort, however, can be a bit of a double-edged sword.

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Erin Onat

Give me some details about Detailed Tees!

Frequently in tech support, when a difficult-to-converge model comes in, one of the first things we check is whether or not any tees in the model are being modeled as detailed tees. The reason for this is that the hydraulic calculations involving detailed tees can be complex due to the interdependence between velocity and pressure loss for each pipe connected to the tee. Iteration must, therefore, be performed to find a pressure loss and flow through each connecting pipe that agrees with the rest of the flow and pressure solutions in the model. This begs the question, then, what calculations...
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Ben Keiser

What Does “Head (HGL)” Mean for Submerged Pumps and Exit Pressures?

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...
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Lisa Converse

Congratulations 2016/2017 Platinum Pipe Award Winners!

AFT received many excellent submissions to the Platinum Pipe Award for 2016/2017, making this year one of the most difficult to judge in the history of the contest. Congratulations to the winners!

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Trey Walters

Seventy-Five Years After Pearl Harbor, Which Was 38 Years After First Flight at Kitty Hawk

Yesterday was the 75th anniversary of the Japanese attack on Pearl Harbor which catapulted the United States into World War II. For Americans, there was no way to miss the abundant news coverage and the stories of vets who were there that day and are still alive today to share their experiences. As I read about and watched some of the ceremonies and news it got me thinking about the astounding progress humankind made in the 20th century in the field of aviation.

The Wright brothers made their first successful, sustained flight on December 17, 1903 near Kitty Hawk, North Carolina. That in itself was an astounding accomplishment. Their Wright Flyer aircraft today resides in the Smithsonian National Air and Space Museum in Washington, D.C. (see below a photo I took in 2008). I could spend days at that museum and the extended air and space museum in Virginia, but alas I only have had time to spend one day at the main museum in Washington D.C. and have not had an opportunity to visit the one in Virginia.

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