Thermal Bubble Motion in Liquid Nitrogen under Non-Uniform Electric Fields

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Description/Abstract

This paper describes an experimental study of the influence of a non-uniform electric field on bubble motion and behaviour in liquid nitrogen. The electric field effect on the bubble motion as it rises to buoyancy within applied dc electric fields is quantitatively investigated using a rod-plane gap. Thermal bubble motion and bubble collision with the plane electrode processes were observed in these experiments. The experimental results show that dc non-uniform electric fields have an obvious effect on bubble behaviour; bubbles move closer to the plane electrode away from a higher field region to a lower one, irrespective of field direction. Furthermore, the bubble dynamic mechanism has been analysed and explained. Results show that the gradient force greatly affects the dynamics of bubbles in the gap. In addition a set of differential equations which describe the motion of a spherical bubble in the rod-plane gap with voltage are given and solved numerically to determine bubble trajectory in liquid nitrogen. Compared to the experiment, the theoretical results show a satisfactory agreement.