Mechanisms of heat transfer for axisymmetric bubble impingement and rebound

Abstract

Heat transfer enhancement resulting from the impingement and rebound of bubbles in confined geometries can play an important role in heat transfer applications. Limited studies exist on the impact behaviour of large ellipsoidal bubbles against a horizontal surface, while the associated fluid flow field has received even less recognition. To address this, the current study investigates the dynamics of a single large ellipsoidal bubble impinging on a horizontal heated surface.The bouncing dynamics have been explored by utilising synchronised high-speed and IR photography. Due to the large bubble size in the present study only a bubble with a low release to surface distance was found to have a symmetric bouncing event. The results showed that separated wake structures initially cooled the surface before the wake structures become counter productive and convect warm fluid onto the previously cooled surface. Two cooling zones were observed; the inner region due to the bubble and the outer region due to the bubble's wake.

Regulation of Bubble Behavior on a TiO2 Photoelectrode Surface during Photoelectrocatalytic Water Splitting

“…Donnelly et al , investigated the mechanism of enhancement effect of sliding bubble movement on the surface heat transfer by injecting gas at the bottom and controlled the heat transfer intensity by changing the angle of the heating surface. Enhanced heat transfer caused by two-phase flow also plays an important role in convection cooling, Donoghue et al , regulated the size and velocity of rising bubbles by changing the diameter and release distance of bottom injection orifice, thus controlling the bouncing behavior of bubbles on the horizontal heating surface and achieving the regulation of heat transfer enhancement. Morick et al studied the oscillatory motion of bubbles in a silicone oil system with temperature gradient and found that the diameter of the floating bubbles oscillated with time, leading to a change in the dominance between buoyancy and thermal Marangoni force.…”