Summary Engineers are often responsible to design systems to comply with codes and standards. In recent years codes that apply to waterhammer and surge pressures have become more prominent. Increasingly AFT Impulse is being used to help engineers comply with such codes. Once AFT Impulse has calculated the maximum pressure due to a transient event, what shall the designer do with this value? The answer to this question depends on the code that is being used as the piping design basis. In this article, we’ll be discussing how two important piping design codes - B31.4 and B31.3 - deal with surge...
We have been hard at work for the last several years on the next generation of AFT software products. These new versions will extend AFT's leadership in the global marketplace and offer engineers unprecedented modeling and user interface capabilities.
May and June are the time for graduations in the USA. My third son graduated from high school this month and will be pursuing a major in Aerospace Engineering. My oldest son is finishing his third year in Mining Engineering and my second son has started into a Mechanical Engineering major. Engineering education and the future of engineering is a frequent discussion topic around our home.
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.
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...