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Lanzhou University (2020)

An Experimental Study on Sand-dust Particle Concentration Due to the Electric Field

周诚;

Titre : An Experimental Study on Sand-dust Particle Concentration Due to the Electric Field

Auteur : 周诚;

Grade : Master’s Theses 2020

Université : Lanzhou University

Résumé
Many aerosol particles carry a certain amount of excess charge.Studies have indicated that the charges of sand particles carried by a particle can reach to thousands of micro coulombs per kilogram.A strong electric field can be generated by the charges carried by the sand particles flying in air,so that an electrostatic force will be acted upon a charged sand particle to alert the concentration distribution and flying time of a particle in air,to stay longer/short in signals of the electromagnetic waves will be attenuated,even to be faded due to the scattering and absorption by the particles.Usually,when the sand/dust concentration is low,the attenuation of the electromagnetic waves is directly proportional to the sand/dust concentration,based on which,we conducted out studies to investigate what the charges carried by the sand/dust particles and the electrostatic field affect the concentration of sand particles in the wind sand flux and a suspended sand/dust system.Firstly,the factors affecting the charges polarity of sand particles are investigated,and it is found that the metallic oxide in chemical composite of sand particles make the particle carry positive charges when the particle size is much uniform,while the larger particles carry the positive charges,and the smaller particles carry the negative charges when the particle size region is larger.Based on the size-dependent charges carried by sand/dust particles,the experimental studies are conducted out to investigate the particle concentration in the sand flux and the suspended sand/dust system.It is found that the electrostatic field alert the particle concentration in the sand flux,and the upward electrostatic field make the particle concentration increase ;the particle concentration close to the sand bed almost be affected by the electrostatic field,while the particle concentration can be enhanced 25% at the height 26 cm above the sand bed.It is also found that the electrostatic field alert the particle concentration and the stay time in a suspended sand/dust system.The results indicated that the upward electric field can speed the sediment of sand/dust particle ;when the initial dust concentration is the same,the80kV/m electric field reduces the dust concentration,except for the initial moment makes the sediment time reduced 75% of the one without electric field.

Mots clés : Sand/dust particle; charge polarity; laser transmittance; particle concentration; sand/dust deposition;

Présentation (CNKI)

Page publiée le 19 mai 2021