壁近傍を上昇する気泡に働く揚力に対する気泡表面状態の影響(流体工学,流体機械)

概要

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Lift forces on both clean and contaminated spherical gas bubbles rising near a vertical wall were determined experimentally below Reynolds number (Re) of 60. We developed an experimental apparatus in which a CCD camera with a microscope follows the rising bubble. We used it to precisely measure the bubble radius, the rising speed and the distance between the bubble and the wall and then estimate the lift force for Re<60. The results show that the lift coefficient of the fully contaminated bubble is always positive due to the viscous effect and the predicting equation for the lift coefficient which was proposed for Re<20 can be applied for Re<60. On the other hand, the lift coefficient of the clean bubble is positive for Re<30. However, the coefficient becomes negative for Re>45 and the attractive force acts on the bubble due to the inertia effect. Consequently, it is found that the surface condition affects on the lift force acting on the bubble rising near the vertical wall.
社団法人日本機械学会の論文
2003-06-25