PIVに基づく気泡乱流チャネルにおけるせん断応力の計測(S19-3 混相流の多次元ビジュアリゼーション(気液・気泡), S19 混相流の多次元ビジュアリゼーション)

概要

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Experiments were carried out to measure skin friction in a horizontal rectagular channel flow which contains various size of air bubbles. First of all, the relationship between the bubble motion and the temporal fluctuation of local skin friction is investigated experimentally at Re =l.lx10^4, in which approximate bubble size ranges from 3 to 30mm. The negative correlation between the local skin friction and the local void fraction is confirmed by simultaneous measurement of shear stress and interfacial visualization. It became clear that the local skin friction decreased in the rear region of large bubbles. Secondly, particle tracking velocimetry is applied to a bubbly two-phase flow to investigate the mechanism of turbulent shear stress modification. We measured three componential stresses with the PTV data at Re=2.0x10^4 and found that a role of the vertically correlated shear stress was important to reduce the total stress effectively.
2004-09-04