Two Phase Flow and Thermal Management Lab
I received a scholarship from NASA and the Ohio Space Grant Consortium (OSGC) to participate in research that aligned with one of NASA’s mission directives - I did this at Case Western’s Two Phase Flow lab.
There, I conducted research on a more accurate way to model a cryogenic transfer line using a mixture model in Ansys Fluent.
I used parabolic flight data from NASA, which showed LN2 flowing through a tube with two thermocouples measuring the wall temperature.
The main point of the research was that with a standard mixture model in Ansys fluent, only one of the wall temperatures would match with the real data. The other wall temperature would match if the Lee coefficient (a phase change rate modifier) was modified, but then the first wall temperature reading wouldn’t match.
There were several NASA cases which I made models to. The process was that I would first verify the Y+ values in the simulation (a measure to ensure that the model is fully capturing boundary layer effects), ensure grid independence, and then begin production runs where I would modify the Lee coefficient and run the simulation on the university’s supercomputer.
Then, with all of the data points of each Lee coefficient, I created a function which changed the Lee coefficient over the length of the transfer line in an attempt to get the wall temperatures to match at both thermocouples. This worked with varying success due to the fact that the downstream Lee coefficient was affected by the upstream Lee coefficient.
This research allows for a more efficient and more accurate model of propellant transfer lines, which is important for long-term manned and unmanned spaceflight.