Migration Dynamics of Gas Bubble Excited by External AC Electric and Mechanical Vibration Stresses

Abstract

The development of gas bubbles is normal and nearly unavoidable in power transformer operation. Bubbles are the result of different stresses such as thermal, electric, and vibration that may lead to insulation failure in oil transformers. Recent studies emphasised on the dynamic effects of bubbles under different non-electric fields in engineering. However, additional investigations are desirable on the behaviours and mechanisms of bubbles under combined stresses of mechanical vibration and electric field. The present study investigates numerically the dynamic behaviours of a monodisperse bubble swelling in an oil transformer exposed to vibrations and an electric field. An established two-dimensional model was used to solve the Navier-Stokes, vibrational and electric field equations. The level-set approach was adopted to track the trajectory and shape of the soaring bubble. The influence of the electric field, vibration frequency, amplitude, and bubble size on air bubble motion and deformation sifted. The outcomes reveal that the bubble size, electric field, and vibration amplitude influence dynamic bubble characteristics. The electric field revealed its contribution to the bubble deformation rising from the initial point. The bubble rising rate showed a dependence on bubble size and vibration parameters.