下击暴流对高速铁路声屏障气动特性的影响

Influence of Downbursts on the Aerodynamic Characteristics of High-speed Railway Sound Barriers

为研究高速铁路声屏障遭受下击暴流灾害时的气动安全特性,本文采用三维、不可压缩N-S方程和适用于风场模拟的RNG k-?湍流模型,对铁路声屏障在下击暴流风场不同径向位置下的流场分布和气动载荷变化进行数值计算分析.结果表明:随着距风场径向距离的增加,近风场中心侧声屏障的侧向力呈现先增大后减小的趋势,当声屏障位于1倍风场直径时所受到的侧向力最大;背风场中心侧声屏障侧向力在位于0.75倍风场直径位置后由正向变为负向,但其侧向力绝对值仍在1倍风场直径位置时达到最大.沿声屏障长度方向,可依次分为中心段(下击暴流射流入口圈内)、过渡段(下击暴流射流入口圈边缘)和外围段(下击暴流射流入口圈外)3个区段,中心段监测单元受到气动载荷影响最为明显;随着下击暴流风速增加,两侧声屏障侧向力均逐渐增大,并与下击暴流风场风速的平方近似成正比.本文研究结果可为下击暴流作用下的铁路沿线设施安全提供理论依据.

In order to study the aerodynamic safety of the high-speed railway sound barrier under downburst conditions,the three-dimensional,incompressible N-S equations and the RNG k-εturbulence model suitable for wind field simulation were used to calculate and analyze the flow field distribut ion and aerodynamic load of railway sound barriers under different radial positions in a downburst wind field.Results showed that with the increase of the radial distance away from the center of the downburst wind field,the aerodynamic load of the sound barrier near the center of the wind field showed a trend of first increasing and then decreasing,and reached the maximum value at the position about one downburst diameter away from the ejection center.Meanwhile,the aerodynamic load direction of the sound barrier at the center of the leeward field changed from positive to negative at the position 0.75 times of the downburst diameter from the ejection center,but reached its maximum at the same position as the windward sound barrier.Along the longitudinal direction,the sound barrier can be divided into three sections:central section(inside the circle of the downburst jet),transition section(at the circle edge of the downburst jet)and peripheral section(outside the circle edge of the downburst jet).The central section of the sound barrier is significantly affected by the downburst field.Furthermore,as the downburst wind speed increases,the lateral force of the sound barrier at both sides increased and was approximately proportional to the square of the downburst speed.The results of this paper can provide a theoretical basis for the safety of railway facilities under the action of downbursts.