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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.
Dylan Witte

Is the Pipe Half Full or Half Empty?

Well that depends on how optimistic you are, but either way you can model partially full pipes with AFT Impulse! This means partially full along the axial direction, as opposed to partially full along the radial direction. This function only works for pipes that have a slope, and when the pipe is partially full it drains from the end with the higher elevation. Pipes which contain vacuum breaker valves, exit valves, spray discharges, or assigned pressures at the outlet can drain or fill during the transient. This draining or filling is limited to the specified pipe. AFT Impulse will not model...
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Dylan Witte

It's Only Logical!

Many engineers are familiar with how “Add/Or” logic works in computer coding or in control systems, which are used often to control transient events such as valve closures and pump start-ups. “Or Logic” determines the conditions that prevent a specific event from happening unless one event OR another event happens. “And Logic” determines the conditions that prevent a specific event from happening unless one event AND another event occur at the same time. It is possible to create this type of logic model within AFT Impulse and AFT Fathom XTS by creating a sub-model within your workspace. This sub-model would not...
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Dylan Witte

Using Liquid Accumulators in AFT Impulse

Many engineers are familiar with gas accumulators and their ability to aid in surge suppression modeled in AFT Impulse, but what about liquid accumulators? Liquid accumulators are different from gas accumulators in that they are assumed to be liquid full and do not have any gas that can compress and expand in order to dampen pressure spikes caused by water hammer.  Liquid accumulators change the system response to pressure spikes, but they operate differently than gas accumulators. There are only three required input parameters for liquid accumulators; Elevation, Elasticity, and Initial Volume. Figure 1: Liquid Accumulator Properties Window Initial Volume is...
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Recent Comments
Aaron Ren
It is great! I didn't use liquid accumulator and it is very helpful for me. And I have a problem about your figure 4 and figure 5,... Read More
Friday, 29 May 2015 05:31
Dylan Witte
Hi Aaron, To create multiple plots on the same graph I created several different groups and then used "Plot Multiple Paths Using ... Read More
Friday, 29 May 2015 19:11
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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.

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Trey Walters

AFT 20th Anniversary Conclusion: Prizes, Awards and the Future of AFT

Last month AFT concluded its 20th year as a world leading provider of fluid flow simulation software products. A year ago I wrote about AFT's 20th anniversary and the prizes we would be awarding.

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Ben Keiser

What About Viscosity Corrections?

Previously, I wrote an article that discussed how to account for density differences between a pump manufacturer's test fluid and a system fluid for pumps as well as the importance, http://www.aft.com/blog/entry/2014/12/02/reference-densities-for-pump-operation.  Both AFT Fathom and AFT Impulse can take into account these density differences very easily, thus, reducing the efforts for the user. But what about viscosity corrections?  Is it important to take this into account as well?  How is this accomplished?  Does it really make a difference? If the system fluid you are modeling has a HIGHER VISCOSITY (more resistant to flow) than the fluid the pump was tested with,...
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Recent Comments
Guest — RJ
Worthful...!!!
Saturday, 13 December 2014 05:04
Guest — SB
Couple of questions: 1. The pump curve data entered, is this for water? 2. How are NPSH-R curves corrected? does the hydraulic i... Read More
Tuesday, 10 February 2015 05:16
Ben Keiser
Hi SB, Yes, the pump curve data entered is assumed to be based upon water. The System Fluid has a higher viscosity than water an... Read More
Thursday, 12 February 2015 18:10
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Ben Keiser

Reference Densities for Pump Operation

You have just received a pump curve from a manufacturer to use in modeling your piping system.  However, the pump manufacturer only tested their pump with water while your system fluid has a density that is different than water.  These differences need to be accounted for with your flow model as well.  This may sound like a bit of a daunting task up front. But there is good news!  In AFT Fathom 8 and AFT Impulse 5, there are two very helpful features that will allow you to easily account for these differences with no trouble at all! The pressure rise...
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Recent comment in this post
Guest — RJ
Quite a helpful information and an important correction feature introduced. Thanks for the Information
Saturday, 13 December 2014 04:51
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