A fluid-thermal coupled analysis based on FEM is conducted. The inner structure of the coils is built with consideration of both the structural details and the simplicity; thus, the detailed heat conduction process is coupled with the computational fluid dynamics in the thermal computation of air-core reactors. According to the simulation results, 2D temperature distribution results are given and proved by the thermal test results of a prototype. Then the temperature results are used to calculate the heat flux to predict the detailed heat transfer process in the packages of the reactors. The study in this paper may be useful in the design optimization in air-core reactors. 1. Introduction With the development of power system, the usage amount of power reactors continues to rise more and more large capacity air-core reactors appear. Air-core reactors with large capacities have more packages and greater heights, which may cause uneven distribution of temperature rise. Thus, the accurate temperature field computational methods are in need. Numerical simulation has been used to analyze the thermal condition of power equipment for a long time. Two categories of numerical approaches were developed as “Network Modeling” [1–6] and finite element method (FEM) [7–10]. The former can describe the heat transfer process clearly, but can only be used when critical temperatures such as hot spots are required and detailed local flow/temperature information is not [5]. The latter is adopted more and more due to its pinpoint accuracy and the detailed information it can provide. Air-core reactors have complex structures with paralleled cylinder packages and vertical air ducts. The heat transfer in them is a hybrid process with heat conduction, convection, and radiation. Thus FEM is obviously better suited than the other computational methods in the thermal computation of air-core reactors. In [11, 12], 2D and 3D fluid-thermal field coupled FEM models are built to compute the temperature field of power transformers and reactors. But the inner structures were not considered and the details of temperature distribution and heat transfer process are not analyzed. In this paper, a fluid-thermal coupled analysis based on FEM is conducted. The inner structure of the coils is built with consideration of both the structural details and the simplicity; thus, the detailed heat conduction process is coupled with the computational fluid dynamics in the thermal computation of air-core reactors. After the analysis, 2D temperature distribution results are given and proved by the test
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