关键词: 输沙率； , 风洞实验； , 理论模拟； , 拟合公式

Abstract: The sand transport rate is the important data to describe wind erosion in wind-blown sand movement. In this paper the sand transport rate is measured in wind tunnel in Saopotou，and considering thermal diffusion and heat convection the multi-field coupling model is established to numerically simulate the process of wind-blown sand movement with LES （Large Eddy Simulation）. Comparing the theoretical results with the experimental results，it is found that wind speed and the sand transport rates of numerical simulation results both are good agreement with the experimental results. With height increasing，wind speed can be divided into two parts: above 35 cm height，wind speed is affected weakly by moving sands，and wind speed obeys the logarithmic distribution as net wind field; at the interval of 0-35 cm height，acted by large amount of saltating sands wind speed is blocked and decreases monotonously. With the wind speed strengthening，the quantity of saltating sands also increases，which causes wind speed gradient decreases gradually. During the process of wind blown sand flux，at the beginning the sand transport rate increases exponentially with time，and then decreases gradually until it reaches the dynamic stability. With wind speed strengthening，the sand transport rate becomes larger，but the duration time becomes shorter. The experimental and theoretical results show that above 10 cm height the sand transport rates of theoretical simulation are good agreement with the experimental results，but below 10 cm height，the theoretical results are obviously bigger in quantity than that of the experimental results. This is because in wind tunnel experiment sand sampler will interfere with the air flow，which causes that some moving sands could not entry sand sampler. Especially at the interval of 0-10 cm height air flow affected by sand sampler will form spiral vortex with undercutting for the sand bed，which is unfavorable for sand sampler to collect the moving sands. At the same time when wind velocity is bigger，suspension quantity of sands increases，which also could not entry sand sampler. There are other factors to cause the experimental results to be smaller than that of true values. But the theoretical simulation solves the problems of low trap efficiency of sand sampler near the sand bed and reduces the error. At the same wind velocity the experimental and theoretical data of the sand transport rate are fitted with least squares method，and the fitting equation   can be obtained，which indicates that the sand transport rate exponentially decreases with height increasing. And in order to further describe the characteristics of the sand transport rate，they are calculated at several height intervals: total sand transport rate and the sand transport rate at different height interval both increase rapidly with wind velocity enlarging. In the interval of 0-10 cm height the percent of the sand transport rate diminishes with the wind speed enlarging，but above 10 cm height in the same interval the percent of the sand transport rate increases obviously with the wind speed enlarging.

Key words: sand transport rate, ind-tunnel experiment, heoretical simulation, itting equation