310 高粒子体積率で存在する粒子に負荷する流体抵抗力の検証(2)(OS3-2 噴流,後流,せん断流の構造・普遍的特性(後流2),OS3噴流,後流,せん断流の構造・普遍的特性)

概要

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The drag coefficient of solid particles falling in the air has been investigated experimentally. Small spherical particles free-fall through quiescent or turbulent flow in which the turbulent level is kept constant with rotating grids as a turbulent generator. Averaged flow property that is changed depending on the charge of the particles is measured by means of LDV. Particle velocity is measured by means of 2D-PTV with laser sheet and CMOS camera. In still flow, by increasing particle volume fraction (up to O(10^<-3>)) the drag force for each particle changes, while in the turbulent flow the drag force for each particle is changed with the change of volume fraction but is relatively insensitive to turbulent intensity. Consequently, the existing empirical drag coefficient for solid particle, which depends only on the particle Reynolds number, is insufficient and it depends on the volume fraction of solid particles and ambient turbulent statistics.
2007-11-17