接触网周围流体流动及传热特性的数值模拟

Numerical simulation of fluid flow and heat transfer characteristics around the catenary

作为电气化铁路牵引供电系统的重要组成部分,架空接触网常年裸露于空气中,易受大风及悬挂结构覆冰等随机环境荷载影响,进而直接影响弓网系统的受流质量,而气动参数和传热参数可反映架空接触网的机械振动特性和温度特性。因此,为探究不同雷诺数下接触网导线的气动参数和传热参数,基于计算流体力学理论建立接触网导线的流体-热耦合数值模型,为验证模型的模拟精度,将数值模拟结果与SST k-ω模型以及公开的实验数据进行比较。结果表明:与SST k-ω模型相比,低雷诺数选用层流模型、高雷诺数选用大涡模型的流体−热耦合数值模型的模拟精度更高,气动参数的最大相对误差仅为7.0%,传热参数的最大相对误差仅为5.8%;在亚临界区内,接触线的阻力系数高于承力索的阻力系数,斯特劳哈尔数则明显低于承力索的斯特劳哈尔数,且其升力系数为负值,明显不同于承力索的升力系数;接触线因沟槽的存在,其换热性能低于承力索的换热性能。

As an important part of the traction power supply system in electrified railways,the overhead catenary is exposed to the air all year round,so it is vulnerable to random environmental loads such as strong wind and icing of suspension structure,which directly affects the current collecting quality of the pantograph-catenary system.The aerodynamic parameters and heat transfer parameters can reflect the mechanical vibration characteristics and temperature characteristics of the overhead catenary.Therefore,to study the aerodynamic parameters and heat transfer parameters of catenary wires under different Reynolds numbers,a fluid-thermal coupling numerical model of catenary wires was established based on computational fluid dynamics(CFD),and the flow field and temperature field around carrier wire and contact wire were numerically simulated by using a finite volume method based solver(Fluent).Meanwhile,the simulation results were compared with the results of SST k-ωmodel and the published experimental data to verify the simulation accuracy of fluid-thermal coupling numerical model.The results show as follows:compared with the SST k-ωmodel,the maximum relative errors of the aerodynamic parameters and heat transfer parameters in the fluid-thermal coupling numerical model are only 7.0%and 5.8%,respectively,which suggests that the simulation accuracy of fluid-thermal coupling numerical model using laminar model for low Reynolds number and large eddy model for high Reynolds number is higher.In subcritical region,the drag coefficient of contact wire is larger than that of carrier wire,its Strouhal number is significantly smaller than that of carrier wire,and its lift coefficient is negative,which is obviously different from that of carrier wire.The heat transfer performance of contact wire is lower than that of carrier wire due to grooves.