交流电场下变压器油中贴壁气泡形变特性

Deformation Characteristics of Bubbles Attached to Solid Wall in Transformer Oil Under AC Electric Field

气泡是油纸绝缘系统的典型缺陷,会显著地降低变压器油的绝缘性能。为了明晰气泡对油纸绝缘系统的危害,搭建了油中贴壁气泡动力学观测平台,研究吸附于电极表面的气泡在交流电场中的形变特性及影响规律。结果发现:油中贴壁气泡沿电场方向拉伸并以100 Hz的频率进行脉动变形;随着电场强度、气泡半径和温度的增大,气泡的变形程度也逐渐增大。基于相场方法搭建了气液两相流仿真模型,仿真与实验结果相互验证,揭示了气泡变形的本质为电场力和表面张力作用的平衡。气泡会影响油隙电场分布,其内部场强随气泡沿电场方向的拉伸而降低。该文研究可为深入评估气泡对液体绝缘的危害和变压器的绝缘设计提供参考。

Air bubbles are a typical defect of oil-paper insulation system,which can significantly reduce the insulation performance of transformer oil.In order to clarify the hazard of bubbles to the oil-paper insulation system,this paper builds a bubble dynamics observation platform to study the deformation characteristics and the influence law of bubbles adsorbed on the electrode surface under AC electric field.It is found that the adherent bubble in transformer oil stretches in the direction of the electric field and pulsates at a frequency of 100 Hz.The degree of bubble deformation increases gradually with the increase of electric field strength,bubble radius,and temperature.A simulation model of gas-liquid two-phase flow is built based on the phase field method,and the simulation and experimental results are verified with each other,revealing that the essence of bubble deformation is the balance of electric field force and surface tension per-formance.The bubble affects the electric field distribution of the oil gap,and its internal field strength decreases with the stretching of the bubble along the electric field direction.The research in this paper can provide a reference for in-depth evaluation of the hazard of bubbles to liquid insulation and design of transformer insulation.