AFT Arrow can be used to model various types of choking such as restriction choking, endpoint choking, and expansion choking. A useful parameter in AFT Arrow’s output is the “Sonic Flow Area” and this is the flow area in which sonic choking will occur. Comparing the sonic flow area to the actual flow area can help determine the margin between not choking and choking. The figure below provides a conceptual understanding of comparing various sonic areas to the actual flow area of a compressible system. If one defines their system such that the sonic area (ASonic,1) is less than the flow...
A frequently asked question at our training seminars - usually during a break or over lunch - is how we came up with the name "Arrow". More completely, the product is named AFT Arrow™ and it is considered by many as the world's leading compressible pipe flow modeling software product.
All of the pipe numbers in Fathom must be unique. When adding a pipe to a model, the new pipe number will be incremented based on the highest pipe number currently in the model. For example, you may only have 25 pipes on the workspace, but if the highest pipe number is 100, a new pipe will automatically be assigned number 101. After several iterations of deleting and adding new pipes, the numbering scheme may be reduced to chaos. AFT Fathom provides three tools to quickly and easily renumber pipes. They can be found in the Edit menu. The Renumbering...
A common task among pipe stress engineers is to evaluate loads on pipe systems caused by waterhammer. Since AFT Impulse 4.0 was released our users have had the ability to calculate waterhammer-induced unbalanced forces for use in any pipe stress analysis application. In addition, our users can create specially formatted transfer files for direct use in CAESAR II and TRIFLEX. However, the process of calculating such forces in AFT Impulse and then applying them in pipe stress software is not as straightforward as it sounds. Our customers have asked for assistance in this process. I have teamed with AFT's distributor in Canada...
Using “Specified Heat Rate In Constants” for the thermal model of heat exchangers can often cause problems in system models. The reason why is because this thermal model type causes the heat exchanger to act like an “assigned heat input” junction as does an assigned flow junction does for providing constant flow rates. Another problem is that this thermal model can cause unrealistic temperature changes across a heat exchanger. When the heat rate is specified and the mass flow rate and heat capacity are calculated based on the system solution, the temperature change will be whatever is required to maintain the...
Many of you probably saw in the news that today, Monday, February 20th, is the 50th anniversary of John Glenn’s flight into space. The flight was aboard a Mercury-Atlas rocket dubbed Friendship 7. This historic event was a significant step on the way to the Apollo missions to the moon.
I have an iPod - to which I am very attached. I hike frequently in the Colorado Mountains near where I live and I can’t do it without my iPod. I can’t work out at the gym without my iPod. I can’t drive my car without my iPod.
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