基于风洞试验的风沙两相流耦合流场特性

Coupling flow field characteristics of wind-sand two-phase flow based on wind tunnel test

风沙两相流结构的理论与研究方法已趋于成熟,主要集中在风沙物理运动本身和防风固沙工程方面,然而,将风沙运动现象及其对建筑结构物的作用效应相结合的研究还比较鲜见,继续开展风沙地区工程结构的抗风沙研究具有重要的现实与工程意义。通过风沙风洞试验,模拟了实际沙漠地貌下的风场特征,重点通过风洞顶部落沙研究了类似沙尘暴环境下的沙浓度、风沙流速度廓线以及湍流强度随高度的变化情况。通过控制相同风速、变化不同输沙率进行落沙,以此形成多种不同类型的风沙两相流耦合流场,并与净风工况相比较。试验结果表明:沙浓度梯度分布与落沙孔数量、控制风速以及高度均相关;风沙流场中沙颗粒的运动对风速剖面有一定的削弱作用,对湍流强度却有增强作用;风场中沙质量浓度沿高度方向的分布特征直接影响了各高度处风速和湍流强度的大小,沙浓度越大的高度处对风速的削弱程度越显著,且对湍流强度的增强程度越大。

The theory and research methods of wind-sand two-phase flow have become mature,mainly focusing on the physical movement of wind-sand and wind-sand consolidation engineering.However,the study of wind-sand movement phenomenon and its effect on building structures is relatively rare.It is of great practical and engineering significance to continue the research on wind-sand resistance of engineering structures in wind-sand areas.In view of this,the wind field characteristics under the actual desert landform are simulated through wind tunnel test.The variation of sand consistency,wind velocity profile and turbulence intensity with height under the similar sandstorm environment is mainly studied through the falling sand on the top of the wind tunnel.By controlling the same wind speed and changing the sand transport rate,sand fall is carried out to form a variety of different types of wind-sand two-phase flow coupled flow field and compare with the non-sand-driving wind.The experimental results show that the distribution of sand consistency is related to the number of sand holes,the control of wind speed and height;the movement of sand particles in wind-sand flow field weakens the wind velocity profile,but enhances the turbulence intensity;the influence of the presence of sand particles in wind field on the wind speed at different heights is directly related to the vertical distribution characteristics of sand consistency,and the larger the sand consistency is,the weaker the wind speed is,and the stronger the turbulence intensity is.