考虑绞凸特征的输电线气动力CFD模拟

CFD simulation of transmission lines aerodynamics considering the twisted convex characteristics

采用商用FLUENT软件,基于雷诺时均模型,以JL/G1A-630/45同心绞线为对象进行二维CFD数值计算,在网格和时间步长无关性检查的基础上,分析网格离散方式和不同雷诺数下输电线的气动力系数及Strouhal数。研究结果表明:为保障CFD数值计算的结果合理性,需开展网格和时间步长的无关性检查;结构网格较非结构网格能更好的模拟绞线的气动力;Re≤1.65×105时,具有绞凸的输电线气动力系数CFD模拟结果随雷诺数的变化规律与等参数的光圆圆截面模拟结果相似,但输电线和圆截面气动力间的数值差异随雷诺数的变化而变化;在常规导线的缩尺状态(500<Re<3000),采用等截面光圆圆截面替代绞线截面,可能会降低导线顺风向的平均和脉动荷载及横风向的脉动荷载,降低St数并提高导线涡振时的风速;即使能真实模拟缩尺导线的表面绞凸特征,由于雷诺数效应,模型和原型状态的气动力数值仍可能存在较大差异。

Using the commercial software FLUENT,the CFD numerical calculation of JL/G1A-630/45 concentric stranded wire was performed based on the Reynolds time-average model(RANS).Based on the grid and time step independence check,the aerodynamic coefficients and Strouhal number of the transmission line under different mesh type and different Reynolds numbers(Re)were analyzed.The results show that in order to ensure the rationality of the CFD numerical calculation results,it is necessary to carry out the independence check of the grid and time step.The structural grid can better simulate the aerodynamics of the stranded wire than the unstructured grid.When Re is less than 1.65×105,the variation of aerodynamic coefficients with Reynolds number is similar to that of circular section with equal parameters,but the difference between numerical values is affected by Reynolds number.What’s more,in the scale state of conventional transmission lines(500<Re<3000),it is possible to reduce the average and fluctuating loads along the wind direction and across the wind direction of the conductor and increase the wind speed when the conductor is in resonance by replacing the twisted-wire section with the circular section of equal diameter.Even if the surface twisted convex characteristics of the scaled wire is truly simulated,the aerodynamic values of the model and the prototype state may be quite different due to the Reynolds number effect.