地铁隧道附属广告设施的活塞风作用时变特性

Time Variant Characteristics of Piston Wind for Billboards Affiliated with Subway Tunnels

为了预测地铁隧道内由活塞风效应引起的广告牌表面风荷载的时变特性,采用计算流体动力学(computational fluid dynamics, CFD)开展了活塞风三维非稳态流动模拟.基于用户自定义函数(user-defined functions, UDF)定义了列车运行控制与动网格控制程序,搭建了精度更高的活塞风模拟方法,并结合以往的实验与仿真,验证了方法的合理性.在此基础上根据实际隧道断面建立了全尺寸动网格模型,考虑了不同运行速度下由列车运动引起的流场变化,重点关注地铁隧道内不同位置广告牌表面的静压变化.研究结果表明,列车经过广告牌时表面静压由正变负,速度增加时会导致广告牌表面的静压显著增大,对于80 km/h的工况静压幅值能超过500 Pa;对于部分以120 km/h运行的地铁,静压幅值超过1 kPa.

In order to predict the time-variant characteristics of a piston wind for billboards in subway tunnels, a simulation based on computational fluid dynamics was employed to solve the three-dimensional unsteady flow problem. User-defined functions were used to define the movement manipulating the train and the dynamic mesh, thereby leading to the establishment of a more accurate simulation method for the piston wind. The rationality of the method was verified according to previously conducted experiments and simulations by Kim. A full-scale tunnel model was then set up based on a real tunnel cross-section. Different train speeds were taken into account to analyse the flow field changes caused by train movements, thus focusing on the changes of the static pressure on the billboard surfaces in subway tunnels. The results show that speed increases cause the static pressure on the billboards to increase significantly, thus changing from positive to negative when the train passes by. The static pressure amplitudes exceed 500 Pa for train speeds of 80 km/h and 1 kPa for some subways at an operating speed of 120 km/h.