列车车体传热系数数值计算方法对比分析

Comparative study on numerical evaluation of the heat transfer coefficient of train body

车体传热系数是检验列车保温、隔热性能的重要指标之一,是采暖、空调等设备选型的主要依据。依靠高精度数值计算方法,可在列车总体设计阶段,对其车体隔热性能进行仿真及结构优化,避免整车制造完成后才能进行车体传热性能评估的局限性。以某地铁列车侧墙为例,分别采用二维典型断面、二维断面拉伸以及三维典型区域3种数值方法对其传热系数进行仿真计算,并比较分析各方法对侧墙以及整车传热系数计算结果的影响。研究结果表明:二维典型截面法比二维截面拉伸法小7.2%,比三维车体传热系数小8.9%。采用二维典型截面法对列车车体传热系数进行数值计算所需计算资源最小,但无法反应真实车体复杂三维结构传热特性,计算结果较其他方法偏小;而三维典型区域计算考虑了第3方向的热对流,以及车体冷桥结构的影响,结果更接近真实车体传热过程,但计算资源消耗大。本研究为列车车体传热系数计算方法的合理选择及误差分析提供参考依据。

The heat transfer coefficient is one of the important indicators for evaluating the thermal insulation performance of train body. In this paper, the heat transfer coefficient of the side wall of the vehicle body with two-dimensional, two-dimensional stretching, and three-dimensional geometric models was computed and analyzed. The results show that the heat transfer coefficient of the two-dimensional method is 7.2% smaller than that of the two-dimensional stretching method, and is 8.9% smaller than that of the three-dimensional method.The heat transfer coefficient of the two-dimensional stretching method is 0.18% smaller than that of the three-dimensional method. Two-dimensional and two-dimensional stretching underestimate the effective heat transfer rate and increase the heat transfer resistance, but can effectively reflect the cold bridges in heat transfer duringcomputation. The actual geometric heat transfer is calculated by using the three-dimensional geometric model as it considers the heat transfer in the third direction, and the result is closer to the experimental results of real train body. This study provides a theoretical basis for the reasonable selection of numerical methods for future research.