Application and Evaluation of STAR-CCM+ for Cryogenic Spray Cooling

In the pursuit of advancing the field of space exploration, it is desired to develop in-space propellant depots to enable refueling of spacecraft after their initial launch from Earth. However, the low saturation temperature of cryogenic propellants results in a tendency for them to boil and vaporize when transferred into a tank that is not adequately chilled, an effect which is coupled with the spray cooling that the injected cryogens impose on the tank itself. Effective tank design requires insight into the complex physics that govern this spray cooling behavior, including multiphase fluid dynamics, wall boiling, coupled solid–fluid heat transfer, droplet injection and atomization, and droplet–wall interactions. As a first step towards modeling propellant tank chilldown in space, this work evaluates how well Simcenter STAR-CCM+ can be made to model the process of cooling an initially hot test plate with a liquid nitrogen spray when using only its off-the-shelf physics models, with particular attention paid to the processes of liquid atomization, droplet–wall interactions, and boiling phenomena. Simulations using the built-in Reitz–Diwakar model capture atomization well, showing good agreement with the experimentally observed droplet size distribution, and the Bai–Gosman model generally predicts droplet wall-impingement behavior. Spray-cooling simulations show decreasing plate temperatures that agree reasonably well with experimental measurements, particularly near the nozzle centerline. However, enhanced heat transfer at locations far from the spray centerline shows an area for improvement.