円柱形粒子の分散を伴う格子乱流場における粒子と流体の運動機構

摘要

粒子の分・散を伴う二相流は，粉体輸送，流動層などrnの工業装置内や，河川，雲などの環境中に頻繁に見らrnれる現象である．したがって，粒子の分散を伴う二相rn流の流体の流動機構および粒子の運動機構を明らかにrnすることは，極めて重要である．rn粒子の分散を伴う流れについては，これまでに数多rnくの研究がなされてきた．%Particle motion and flow structure were experimentally investigated in grid-generated turbulence with spherical or columnar particle dispersions. Particle motions were taken by a high speed video camera and instantaneous streamwise and horizontal velocities were measured using a PIV. The results show that columnar particles fall without clustering in the free-falling particle experiment, whereas spherical particles form clusters during the falling process. Turbulence intensity in the grid-generated turbulence with columnar particle dispersion is larger than that in the turbulence with spherical particle dispersion. It is found by flow visualization that these differences in particle motion and fluid structure are attributed to the irregular horizontal movements and rotation of columnar particles.