Effect of Marangoni induced instabilities on a melting bridge under microgravity conditions. (November 2021) - Šeta, Berin
Highlights: Analysis of melting process in n-octadecane bridge. Frequency analysis of the temperature oscillations for various temperature gradients. Marangoni effect influence on phase change rate. Effect of the instabilities on melting efficiency. Influence of Marangoni number on wave patterns and mode number. Abstract: The present work is focused on the 3D numerical analyses of the n-octadecane melting process, under microgravity conditions and Marangoni convection, by using the configuration of the liquid bridges (melting bridge). These analyses were conducted for various temperature differences (ΔT) between hot and cold plates ranging from 18 K up to 50 K. The temperature oscillations in one point of the bridge volume showed distinctive behavior in three different ranges of ΔT. These domains have been fully characterized in terms of frequency and wave patterns. Standing and travelling wave modes of different wave numbers have been observed and the instabilities produced within their transitions have been deeply analyzed. The results showed that the complexity of the flow increased with ΔT and oscillation frequencies decreased while the melted fraction increased. Moreover, Marangoni convection enhanced the heat rate efficiency by a factor of 1.7 approximately compared to a pure conductive process, which depended on temperature difference applied.