The insulation performance of SF₆ insulated high voltage direct current apparatus are often analysed in a pure electric field or electro-thermal coupled field while the fluid behaviour of SF₆ gas flow is often ignored. However, frequent flashover along the support insulators inside the SF₆ insulated wall bushing indicates that the fluid characteristics of SF₆ may have considerable influence on the interior insulation performance of the bushing. This paper has simulated the thermo-fluid coupled field in the SF₆ insulated wall bushing based on the finite element method model. The result shows that buoyant flow of SF₆ has evident influence on the temperature distribution in the bushing. On this basis, the effect of the thermo-fluid field on the electric field distribution along the insulator as well as on the motion behaviour of the metallic particles is analysed. Furthermore, the effect of different thermal boundary conditions on analysis of the multi-physics field in the bushing is discussed and the most suitable one for simulation and experiment is suggested. Comparisons are made between different supporting structures and modification advices are proposed. This paper can serve as a good reference for subsequent research studies on SF₆ insulated apparatus in which the temperature gradient or the motion of the micro-sized metallic particles shall be considered.

中文翻译：

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SF6 绝缘高压直流套管中的热流场建模及其对电场分布和金属颗粒运动的影响

_{SF 6}绝缘高压直流电器的绝缘性能往往在纯电场或电热耦合场中进行分析，而SF ₆气体流动的流体行为往往被忽略。然而，SF _{6绝缘穿墙套管内部沿支撑绝缘子的频繁闪络表明SF 6}的流体特性可能对套管的内部绝缘性能产生相当大的影响。本文基于有限元法模型对SF _{6绝缘穿墙套管中的热流体耦合场进行了模拟。}结果表明，SF _{6的浮力流动}对套管内的温度分布有明显的影响。在此基础上，分析了热流场对沿绝缘体的电场分布以及金属颗粒运动行为的影响。此外，还讨论了不同热边界条件对套管中多物理场分析的影响，并提出了最适合仿真和实验的边界条件。对不同的支撑结构进行了比较，提出了修改建议。本文可为后续研究SF ₆绝缘设备的研究提供很好的参考，其中需要考虑温度梯度或微小金属颗粒的运动。