Experimental determination of dynamic shape factors by comparison of the coulter and impactor techniques

摘要

Particle size and shape are important characteristics because they largely influence the aerodynamic behaviour of aerosols.Among the several existing shape factors,the dynamic shape factor is often used.It is defined as the ratio of the drag force on a particle to the drag force on the particle's mass equivalent sphere at the sedimentation velocity.For non-porous particles,the dynamic shape factor relates the aerodynamic diameter to the volume-equivalent diameter.Although a substantial data base exists in the literature (Allen et al.,1978;Barbe Le Borgne et al,1986;Brockman et al,1990;Cheng et Allen,1988a;Cheng et al,1988b;Wu et Colbeck,1996),no data have been reported on the particle size dependence of the dynamic shape factor for polydisperse aerosols made of glass micro-beads and alumina particles.