AFT Blog
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...
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...
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 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.
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, https://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,...
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...
Within the world of pumping system specialists there is a wide range of areas of domain expertise. I was reminded of this earlier this month while attending the AFT Calgary User Group meeting sponsored by AFT's Canadian channel partner. One of the invited speakers, Jordan Grose of Beta Machinery, used several areas of domain expertise to solve a waterhammer problem in the field. I will discuss more about Mr. Grose's presentation later in this article.