An insight into the heat transfer and the flow characteristics for mixed convection horizontal cross-flow film boiling over an arbitrarily oriented ellipsoid

Abstract

The present study numerically investigates the problem of mixed convection horizontal cross-flow film boiling over an arbitrarily oriented ellipsoid. The numerical methodology employs the multi-directional moment of fluid (MOF) method to track the interface over a fixed Eulerian grid. We investigate the effect of different flow and geometrical parameters on the flow dynamics and heat transfer characteristics of the problem. At low Reynolds numbers, a periodic vapor bubble ebullition cycle is observed. However, the vapor bubble pinch-off location shifts away from the heated ellipsoid as the non-dimensional wall superheat increases. Additionally, the non-dimensional departure diameter of the vapor bubble is observed to decrease as the Reynolds number increases. In contrast, the non-dimensional departure diameter of the vapor bubble increases with an increase in wall superheat. The periodic vapor bubble ebullition cycle reveals that the flow field around the heated ellipsoid is intricately connected to the dynamics of the interface, with recirculations forming and dying near the heated interface as a result of the movement of the interface. At a high Reynolds number, the vapor wake completely shifts to the rear of the heated ellipsoid. The coefficient of vapor drag on the heated ellipsoid is observed to decrease as the aspect ratio increases. The asymmetry in vapor mass generation around the heated ellipsoid was observed to decrease with the orientation of the heated ellipsoid.