Interaction of Asymmetric Films Around Boiling Cylinder Array: Homogeneous Interface to Chaotic Phenomenon

Abstract

We report numerical study of film boiling around hot and horizontal cylinders in a saturated water pool to establish interfacial interactions leading toward dryout. Volume of fluid-based finite-volume discretization is performed in the domain for incorporation of source term in mass momentum and energy conservation equations due to phase change. At first, film boiling around single cylinder is simulated at different surface temperatures to understand unconstrained film growth and subsequent film bubble release due to buoyancy. Using velocity vectors and temperature contours, effect of film flow dynamics on bubble departure is depicted. This study has been extended further with multiple cylinders in three different stacking arrangements in order to understand the interaction of films in vicinity. Vertical interaction between cylinders leads to suppression of bubble release at the lower cylinder in comparison to the upper one. In the case of horizontal interactions, bubbles attract each other and merge, provided favorable pitch between cylinders and temperatures of the surfaces is maintained. Offset four cylinders stack maintaining vertical and horizontal pitch allows both lateral vapor affinity and bubble suppression in the lower most cylinder simultaneously. With time interaction of accumulated vapor films around cylinders hinders replenishment of fresh liquid to the hot surfaces leading toward chaotic phenomena or dryout in boiling heat transfer.