Thermal characteristic is one of the key performances of dry-type on-board traction transformer (D-OBTT), which directly affects the operation safety of the new generation electric multiple units. However, due to the particularity of train-induced wind cooling mode of D-OBTT, the existing efficient thermal modelling methods cannot be used under fluctuating air velocity and load. A time-saving transient thermal model for D-OBTT is proposed. First, the framework of the transient thermal network model (TTNM) is proposed considering the coexistence of non-fully and fully developed state of the train-induced wind and the addition heat flow in the solid domain. Then, a novel formula for calculating the length of non-fully developed section considering the geometric dimensions and heat flux density is proposed based on computational fluid dynamics (CFD) parametric sweeps for the first time. The accuracy of TTNM is validated by a D-OBTT experimental setup, and the time consumption is significantly reduced compared with CFD.

中文翻译：

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动车组列车诱导风冷干式车载牵引变压器暂态热网络模型

热特性是干式车载牵引变压器（D-OBTT）的关键性能之一，直接影响新一代电力动车组的运行安全。然而，由于D-OBTT列车诱导风冷却模式的特殊性，现有的高效热建模方法无法在脉动风速和载荷下使用。提出了一种省时的 D-OBTT 瞬态热模型。首先，考虑列车诱导风非完全发展状态和固体域附加热流并存的情况，提出瞬态热网络模型（TTNM）框架。然后，首次基于计算流体动力学（CFD）参数化扫描提出了一种考虑几何尺寸和热流密度的非完全展开截面长度计算新公式。TTNM的准确性通过D-OBTT实验装置进行验证，并且与CFD相比，时间消耗显着减少。