Experimental And Theoretical Study Of Charge Of Perpendicular Lift-off Sand Particles

The mechanism of sand electrification is an important subject of the study of blown sand physics. Due to lattice substitution in sand particles and other reasons, sand particles can carry charge. There is water film on the natural sand particle surface, which lead to form diffused double layer. The diffused double layer breaks up during the lift-off of sand particle, which lead to the electrification of sand particle. Centering on fluid lift-off of sand particle, we study the charge quantity carried by sand particle after lifting off. Main works are as follow:1.We first study the physical chemistry properties of sand surface, and analyze the components and specific surface of sand particle and the net charge carried on sand particle surface. According to the components of sand particle in desert, we suggest the mechanism of sand electrification is due to double layer breaks.2. Based on the results of surface charge, we give an empirical formula. The formula varies with the parameters of sand—such as diameter, density and environment factors—such as external electric field, humidity of air and the PH value. With the increase of sand diameter, the quantity of charge decrease. And with the increase of humidity, the charge quantity increases and then varies slowly and then decrease. With the external electric field increase, the charge quantity decrease. And with the increase of PH value, the charge quantity turns to negative from positive.3.By using a new equipment—air-powered measurement platform for sand, we measure the charge quantity of lift-off sand particle, and we obtain the undetermined coefficient in the empirical formula. We find that the main factors which influence the quantity of the charge are humidity, electric field, sand diameter, and specific surface area. And then, we measure the charge quantity of carbon particle, the results verify the validity of the empirical formula and the main factors.