雾流降雨粒径及其在坡面上生成流动的深化研究

An in-depth study of particle size of atomization rainfall and generated flow on a slope

雾化水流是水利枢纽高速泄流时所形成的一种非自然降雨与水雾弥漫现象,其对高水头、大流量、复杂地质条件的水利枢纽安全运行的潜在威胁很大.通过实验研究及数值模拟对雾流降雨雨滴的粒径分布进行了探讨;采用基于水深平均的平面二维数学模型对雾流降雨在坡面上生成的流动进行了数值模拟,并特别关注了雾流降雨局域分布对坡面径流的影响.研究成果表明:1)雾流降雨雨滴中值粒径沿水舌风方向具有先沿程增大,达到最大值后再沿程逐渐减小的变化趋势,且其达到最大值的纵向位置与降雨强度达到最大值的纵向位置并不重合;雾流降雨雨滴中值粒径沿垂直于水舌风方向呈单调递减的趋势.2)雾流降雨因集中在局部区域,与自然降雨形成的坡面径流相比,其产流达到稳定的历时要高于自然降雨;水深与流速沿纵、横向变化的幅度要高于自然降雨,降雨强度大的区域水深与流速也大.

Atomization flow is a kind of unnatural rainfall and suspended mist,which brings a potential threat to the safe running of the hydraulic project with the characteristics of high water head,great discharge and complicated topography.The distribution of sizes of the atomization rainfall is studied by both laboratory experiment and numerical simulation.The slope runoff generated by the atomization rainfall is simulated by a water depth-averaged 2D model;and the localization of rainfall intensity in space is specially considered.The results show that： 1） The median rain size of atomization rainfall would increase in the longitudinal direction at first,then monotonously decrease;and the longitudinal position relative to its maximum value is not in consistent with the position relative to the maximum rain intensity.In the lateral direction the median rain size would monotonously decrease.2） Since the atomization rainfall is strongly distributed in a localized area,the duration for its runoff yield to reach a steady state is larger than that of natural rainfall;the ranges for the variation of water depth and velocity in longitudinal and lateral directions are higher than that of natural rainfall.