高粒子体積率で存在する粒子に負荷する乱流中の流体抵抗力(流体工学,流体機械)

概要

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A descending rate of falling particles through a quiescent or a turbulent airflow, in which the turbulent level is kept constant by rotating grids as a turbulent generator, has been investigated considering particle volume fraction and Stokes number as experimental conditions. In the experiment, turbulent flow properties and downward flow induced by particles are measured by means of LDV. Particles velocity is measured by means of 2 D-PTV with laser sheet and CMOS camera. As a consequence, in the quiescent flow a descending rate is reduced for the particles with diameter 0.5mm and volume fraction of 10^<-4>, and further reduction is expected by increasing volume fraction. While, the effect of volume fraction range is expected to be different depending on the diameter. On the other hand, in the turbulent flow (St〜10^3), the descending rate is increased but its mechanism is not explained by existing studies. In the case of solid-air two phase flow, the motion of particles are governed by drag and gravity so that a discrepancy of descending rate between present experiment and prediction by existing equation indicates a change of drag under present experimental conditions.
一般社団法人日本機械学会の論文
2009-01-25