Senior Aerospace Ketema
El Cajon, CA USA
You don’t have to be a rocket engineer to use Fathom or Arrow... unless your job is rocket engineering. KETEMA designs systems for re-usable and expendable launch vehicles (ELV’s), today’s formal term for rockets. The design of fluid and thermal aspects of the ELV systems at KETEMA is the responsibility of Ichi Wakabayashi, Senior Mechanical Engineer. He chose Fathom 2 and Arrow 1 to help his group model the many fluid systems aboard an ELV.
Some of the reasons Wakabayashi cited for choosing software were ease of use and the extensive database of fluid properties and component loss coefficients. Since the release of this case study, has implemented three other fluid databases, the Chempak database, NIST REFPROP, and ASME Steam/Water tables. Both Chempak and NIST REFPROP allow for mixtures and dynamic mixing in Arrow.
“Previously, analyses were done by hand, which was tedious and time consuming”, Ichi said. “Allowsws a repeatable tool for flow analysis that allows faster modeling of systems...with good graphical and tabulated outputs.” Unruly analysis by hand, or more commonly now with spreadsheets, is still one of the common reasons users rely on software. Especially as system complexity grows with branching networks, heat transfer, and compressibility, it is harder and harder to be confident in hand calculations or spreadsheet alternatives.
KETEMA has used Fathom and Arrow on numerous systems including: Pressurization systems, nitrogen attitude control systems, and LO2, RP-1 and Ethanol propellant feed systems. The Arrow 1 model of the gaseous helium pressurant system for propellant tanks is shown in Figure 1, mirrored with the modern Arrow 8 model. It is surprising the file still opens, let alone runs in a version 24 years later. Since 1997, has also added isometric modeling options and other workspace improvements to make it easier to interpret your model.
KETEMA had opportunity to check the Fathom predictions against test data. Fathom predictions of the rocket engine propellant feed system pressure drop agreed within 5% with data collected during firing tests on an engine test stand. Even 24 years ago software was tested and verified against field data. With the annual Platinum Pipe Award, even more case studies emphasizing result accuracy and data correlation are submitted each year.
With the many aerospace fluid systems encountered at KETEMA, it appears that Fathom and Arrow will be put to good use in the future as well. With such unique piping systems, it is gratifying to
see demonstrated software’s flexibility as general purpose pipe flow analyzers
Senior Aerospace Ketema is a leading provider of components for aircraft and turbine engine builders, as well as precision products for space, marine and ground-based applications. Ketema specializes in producing complex fabrications and machined components from Titanium and Nickel Alloys.
