风沙流对戈壁地区挡风墙响应规律的数值模拟分析

基于FLUENT欧拉双流体模型,对兰新铁路沿线既有挡风墙周围风沙两相流运动特性进行数值模拟,得到挡风墙背风侧的流场分布特点以及积沙情况。结果表明:挡风墙背风侧风速廓线变化规律呈指数增长趋势,在0.5 m至挡风墙自身高度区间内变化较为复杂,呈先减小后增加的趋势;挡风墙背风侧近地表气流速度反向增大后沿着初始速度的方向减小为0且继续增大至初始速度大小,风速最大值增加的幅度保持在50%左右,风速越大,气流的削弱作用越明显;当初始气流速度为较小时,线路上积沙较少,沙粒多数堆积在挡风墙背风侧墙角处;随着风速的增加,单位时间内通过挡风墙的沙粒增多,由于过流断面减小,气流扩散,更多沙粒沉积在线路上;在强风地区,布设挡风墙时应考察线路上风向的地表情况,沙源比较丰富时应采用工程治沙措施来减小风沙流密度,达到防沙的目的。

Numerical Simulation Analysis of Response Law of Wind-blown Sand Flow around Wind-break Wall in Gobi Area

Numerical Simulation of the motion characteristics of wind-blown sand flow around the existing wind-break wall along Lanzhou-Urumqi Railway based on FLUENT eulerian two-fluid model is conducted to identify the distribution features of the flow field and accumulated sand at the leeward side of wind-break. The results show that,wind profile change law shows an exponential increasing tendency at the leeward side of wind-break wall,the changes at the height of 0. 5 m to wind-break wall itself are complex and tend to decrease and then increase; the airflow velocity on near-surface at the leeward side of wind-break wall is increased in the reserve direction,reduced to 0 along the direction of the initial velocity,continued to increase to the initial velocity,and the maximum wind speed increase rate remains at about 50%,the higher the wind speed,the more obvious the airflow of weakening effect; when the initial velocity is small,less sand is accumulated on the line,and sand accumulation is concentrated at the corner of the leeward side of wind-break wall; with the increase of wind speed,more sand passes through the windbreak in unit time and even more sand is deposited along the line due to the reduction of flow cross-section and diffusion of air; in strong wind areas,the surface conditions affecting wind direction should be investigated before wind-break wall is located,engineering measures should be taken where sand source is rich to reduce sand flow density and prevent sand invasion.