基于对流换热系数修正的钢箱梁温度场研究

Study on Temperature Field of Steel Box Girder Based on Modified Convective Heat Transfer Coefficient

为了研究对流换热边界条件对钢箱梁温度场分布的影响,提出了一种基于对流换热系数修正的钢箱梁温度场数值模拟方法。首先,基于商用软件Fluent计算了钢箱梁截面附近的风速分布,其次,以Fluent计算得到的钢箱梁截面各表面风速修正对流换热系数,并基于ANSYS有限元软件进一步对比研究了不同工况下钢箱梁温度场的分布特征。钢箱梁表面风场计算结果表明:与入口风速相比,钢箱梁截面各表面的风速呈现出不同程度的降低,其中背风侧风嘴上板表面风速降低95.5%,底板表面风速降低17.7%。钢箱梁温度场计算结果表明:与不考虑对流系数修正的钢箱梁温度场相比,考虑对流系数修正后,钢箱梁的横、竖向正温差明显增大,在计入桥面附属设施的影响后钢箱梁横截面的竖向正温差会进一步加剧。桥面铺装对钢箱梁横截面的竖向温差几乎没有影响,仅将最大温差出现的时间延后1 h。此外,由于横隔板的导热性较好,横隔板的存在会明显减小钢箱梁截面的日温差。因此,在钢箱梁温度场计算中,钢箱梁表面风场、桥面附属设施以及横隔板对钢箱梁温度场的影响不能忽略。

In order to study the influence of convective heat transfer boundary conditions on the temperature field distribution of steel box girder,a numerical simulation approach based on the modified convective heat transfer coefficient was proposed.Firstly,the commercial software Fluent was employed to simulate the wind velocity field of the steel box girder.Secondly,the convective heat transfer coefficient of the steel box girder computed and obtained with the Fluent was modified,and the temperature field distribution of steel box girder under different working conditions was further comparatively studied through finite element software ANSYS.The computation results of wind field on the surface of steel box girder show that compared to the inlet wind velocity,the wind velocities near the exterior surfaces of the steel box girder all decrease in different degree.Specifically,the wind velocities near the upper plate of the leeward side fairing and the bottom plate are reduced by 95.5%and 17.7%,respectively.The results of temperature field of steel box girder indicate that after introducing the modified convective heat transfer coefficient,the temperature differences in the steel box girder increase both vertically and horizontally.The vertically temperature difference will further increase after taking the auxiliary facilities on the bridge deck into the numerical simulation.Bridge deck pavement has little influence on the vertical temperature difference of steel box girder except the delay of the occurrence time of maximum temperature difference by 1 hour.In addition,the diaphragm can reduce the vertical and horizontal temperature differences of the steel box girder,due to its superior thermal conductivity.Therefore,the calculation of the temperature field of steel box girder should not ignore the influence of wind field near the surface of steel box girder,auxiliary facilities of bridge deck and diaphragm plate on the temperature field of steel box girder.