Research On High-speed Saltating Particles’ Trajectories In Aeolian Sand Transports

Revealing the movement rule of the particles in aeolian sand transports has important reference value to forecast control of land’s wind erosion and dust storms.In order to obtain the movement parameters’ statistical characteristics of particals with longer trajectory, reveals the causes of high-speed saltating particles’ trajectories, In this paper, through improve the high-speed photography test system in wind tunnel, and telephoto shooting the four different particles of low-speed and high-speed particles’ trajectories within the vision 200 mm. Then use the Motion Studio image processing software for image capture and identification, statistics processing the saltation of particles’ trajectories coordinates data, get the saltation particles movement parameters such as the instantaneous velocity、acceleration、jump distance and time, analysis and reduction of saltation particles trajectory.The results showed that:( 1) In the whole movement stages, in the horizontal direction, horizontal velocity of particles value showed a increasing trend, the particle size bigger, thexv up andxv in smaller; thexv in /xv up is greater than 2, the particles size increase, the ratio will increase accordingly. In the vertical direction, the velocity of particels decreased first and then increased; theyu in/yu up value is less than 1;yu up has nothing to do with the particles size.(2) In the process of particles in air, horizontal and vertical displacement accord with quadratic function in rising stage and decline stage, shows that the air drag force and the particle interactions is constant in 0.06 s. In the horizontal direction,xa is positive, with the growth of air and particles action time,xa is decrease; In the vertical direction,ya is negative, with the growth of air and particles interaction time,ya is irregular change.(3) Different particle size uniform particles coefficient of correlation distance andtime in more than 0.6, greater correlation; Jump distance associated with horizontal takeoff speed, with little relationship between speed of motion parameters; The relationship between the motion parameters has nothing to do with particle size.(4) The high-speed particles’ statistical data shows that, the interaction between the airflow and the particles is divided into stages, turbulence fluctuation are diversity in each stage. The formation of high-speed particles’ trajectories is caused by a variety of factors,single factor cannot be used as the basis for argument.