风屏障对平层公铁桥上列车气动特性影响的风洞试验研究

Wind tunnel test studies on the influences of wind barrier on the aerodynamic characteristics of trains on a highway and railway same-story bridge

基于列车测压试验,以平层公铁桥梁和CRH2列车为背景,分析了风屏障对平层公铁桥上列车表面风压分布的影响,研究了有无风屏障时列车表面压力以及气动力的跨向相关性的变化规律。研究结果表明:设置风屏障后,列车迎风面与背风面、顶面和底面风压差随风屏障透风率的减小而减小,使得列车总体侧力和升力减小,风屏障透风率为20%时,列车表面脉动压力分布较均匀,有利于桥上列车运行时的安全与舒适。风屏障的防风效果不会随着风屏障高度的增加一直变好,透风率为40%时,风屏障存在一个最优高度3.5 m。风屏障透风率对列车迎风面以及顶面圆弧过渡段表面风压的影响明显大于高度。设置风屏障后,列车底面和背风面测点压力跨向相关性更好,风屏障的挡风效应增强了这两部分展向流场的一致性,使流体的脱落点更一致。随着跨向间距的增大,气动力的相关性越来越差,风屏障对气动力的跨向相关性较无风屏障时弱,设置风屏障时跨向间距超过5倍列车高,气动力完全不相关。

Based on the train pressure measurement experiments,the influences of wind barrier on the wind pressure distribution of the train surface on a highway and railway same-story bridge and CRH2 train are analyzed.The change rules of the correlation be-tween the train surface pressure and the aerodynamic force are also studied with/without considering the wind barrier.The results show that when the wind barrier is set,the air pressure differences between the windward and leeward side,top and bottom of the train decrease with the reduction of the air permeability of the wind barrier,which makes the overall side force and lift of the train reduce.When the air permeability of the wind barrier is 20%,the fluctuating pressure distribution on the train surface is uniform,which is conducive to the safety and comfort of the train running on the bridge.The windproof effects of the wind barrier do not al-ways get better with the increase of the height of the wind barrier.When the air permeability is 40%,the wind barrier has an opti-mal height of 3.5 m.The influence of the air permeability of the air barrier on the surface wind pressure of the windward side and the arc transition section of the top side of the train are obviously greater than those of the height.After the wind barrier is set,the pressure cross-correlation between the measuring points on the bottom and the leeward side of the train is better.The wind barrier effect enhances the consistency of the two parts of the flow fields,and makes the falling point of the fluid more consistent.With the increase of span distance,the correlation of aerodynamic force gets worse.The correlation of wind barrier to aerodynamic force is weaker than that without the wind barrier.When the wind barrier is set,the aerodynamic force is completely irrelevant when the span distance is more than 5 times of the train height.