DOI: 10.1615/ICHMT.2009.TurbulHeatMassTransf
ISBN Print: 978-1-56700-262-1
ISSN: 2377-2816
Average velocity of small falling particles in homoge-neous and near-isotropic turbulence − Infulence of turbulence on motion of falling particle
ABSTRACT
The average fall velocity of small and heavy particles in homogeneous and near-isotropic turbulence has been measured by taking multi-exposed photographs of a number of particles. Homogeneous and nearly isotropic turbulence was generated by counter-rotating four grid-blades. Influence of high concentration of particle on amplifying the particle average velocity is minimized by introducing a particle at the very low particle flow rate (about ten particles per second). It is distinguished that there are two kinds of average of falling particles, i.e. line average and space average. The slower particle stays longer than the faster particles in the measureing area and the space average is biased. It is found that the particle average falling velocity increased by 80 % (at maximum) of Eulerian fluid turbulence. Fluid seen by particle, which was estimated through equation of particle motion and measured particle velocity and acceleration, increases when particle average falling velocity increases. Great care must be paid when the results are compared with the others and influence of turbulence on particle falling velocity is modelled.