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Volume 21, Issue 2
Displaying 1-3 of 3 articles from this issue
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Papers
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Toshiro MIYAHARA, Naoki NAGATANI, Seigo SHIMADA, Kenji DAIKOKU2007 Volume 21 Issue 2 Pages 168-176
Published: June 15, 2007
Released on J-STAGE: March 12, 2008
JOURNAL FREE ACCESSExperiments were performed to investigate splitting bubbles formed by liquid flow through a Raschig ring packed bed. A liquid was discharged vertically upwards through a packed bed into a large volume of the same liquid. Shear layers were thus formed both in the packed bed and around the jet. A bubble rising through the packed bed and the jet splits in each layer. The measured bubble size distribution can be well represented by an upper limit log-normal probability function with two constant parameters and only one variable, the maximum stable bubble diameter. In this operation, micro-bubble, the diameter of which is less than 1 mm, was confirmed with increasing liquid velocity through a packed bed. Furthermore, we need mean bubble diameter to give the distribution of splitting bubbles the full picture. Therefore, a correlation equation for volumetric mean bubble diameter of splitting bubbles is presented.View full abstractDownload PDF (1760K) -
Takuro KIKUCHI, Yusuke FUKUSHIMA2007 Volume 21 Issue 2 Pages 177-184
Published: June 15, 2007
Released on J-STAGE: March 12, 2008
JOURNAL FREE ACCESSRepresentative phenomena of solid fluid two-phase in nature are snowdrift and suspension flow in an open channel. The numerical analysis using the turbulent diffusion equation and the k-ε turbulence model is carried out. The agreement between the experimental data and the numerical analysis for both cases is well. The flow can be reproduced by the numerical analysis. The near-bed boundary condition for the turbulent diffusion equation is important and is expressed by the entrainment coefficient that is obtained from concentration flux of solid particles divided by the terminal velocity of particles. The idea of entrainment coefficient is effective for both flows. The values of the entrainment coefficient for snow particles and sediment particles are estimated by the numerical analysis and measurements. Based on these results, the effecttiveness of the entrainment coefficients is discussed comparing with the Garcia's experimental equation.View full abstractDownload PDF (515K) -
Kenji TANAKA, Masahiro TAKEI, Deog Hee DOH, Tomomasa UEMURA2007 Volume 21 Issue 2 Pages 185-192
Published: June 15, 2007
Released on J-STAGE: March 12, 2008
JOURNAL FREE ACCESS3D velocity component of swirling flow behind a rod-like material with orientation and without orientation in a vertical pipe have been measured by stereoscopic-PIV. Four optical sensors are attached to the main vertical pipe in order to detect the orientation. As a result, in the case of rod-like material with orientation, the velocity of Y component turns to negative values from positive values as X direction increases. That is caused by a possibility that a large-scale swirl occurs by the vibration of a rod-like material. Z component has peak value near the oriented material. The value is decrease the peak moves to the pipe center as the horizontal position reaches the center. The turbulence level of Z component, at the lower side of a rod-like material is larger than the middle and upper sides. The influence of turbulence of Y component under a rod-like material.View full abstractDownload PDF (1157K)
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