摘要
风沙流是大气边界层的典型气固两相流,输沙率对风速的响应滞后时间,被称为风沙流响应时间。通过野外测量发现风沙流响应时间与风速测量高度成正比,通过对瞬时风速进行信号分解并计算近地表输沙率与不同时间尺度风速信号之间的相关性,发现响应时间随风速频率的减小而增加。为进一步得到定量的规律,采用数值模拟的方法分析了周期来流风场中,风沙流响应时间随各种参数(周期\,湍流强度\,来流摩阻风速和测量高度等)的变化规律。模拟结果显示:响应时间与风速变化周期、来流摩阻风速成正比,与湍流强度和边界层高度成反比,输沙强度对跃移层外风速变化的响应时间沿高度先增加后减小。
Wind-sand flow is a typical gas-solid two-phase flow occurring in the atmospheric boundary layer in which the sediment transport rate has a response time to the change of wind velocity named wind-sand flow response time. In this paper, we obtained that the response time of wind-sand flow is proportional to the measured height of wind velocity by field measurement. Based on the signal decomposition of instantaneous wind velocity and the correlation between near-surface sediment transport rate and wind velocity signal at different time scales, it is found that the response time increases with the decrease of wind velocity frequency. In order to obtain a quantitative rule, the response time of wind-sand flow with various parameters(period, turbulence intensity, incoming friction wind velocity and measured height, etc) in periodic flow field is analyzed by means of numerical simulation. The simulation results show that the response time is proportional to the period of wind velocity and the incoming friction wind velocity, and inversely proportional to the turbulence intensity and the height of the boundary layer. As height increases, response time first increases and then decreases.
作者
靳婷
彭晓庆
王萍
Jin Ting;Peng Xiaoqing;Wang Ping(MOE Key Laboratory of Mechanics on Disaster and Environment in Western China/College of Civil Engineering and Mechanics,Lanzhou University,Lanzhou 730000,China)
出处
《中国沙漠》
CSCD
北大核心
2020年第2期100-108,共9页
Journal of Desert Research
基金
国家自然科学基金项目(11490551)
兰州大学中央高校基本科研业务费专项资金重点项目(lzujbky-2018-k07)。
关键词
风沙流
非定常风场
响应时间
数值模拟
wind-sand flow
unsteady wind field
response time
numerical simulation