2821 超純水中を上昇する気泡の挙動

概要

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The effect of contaminant on a bubble rising velocity in water is experimentally investigated. An extremely purified water, i.e. a ultrapure water, is used in the experiment and 3-pentanol is adopted as the contaminant. An experimental apparatus that keeps the quality of the water is constructed. In the present study, experiments are conducted for bubbles whose Reynolds number is in the range of 250<Re<600. The temporal behavior of a single bubble motion is recorded by a high speed video whose maximum resolution is 512×480 pixels. It has been often reported that an oscillatory motion of a bubble is observed in a usual water beyond Re=200. However, the bubble in the ultrapure water rises straight and no oscillatory motion is observed at the Re up to 550. Owing to investigate the contaminant effect on the bubble motion quantitatively, the drag coefficient (C_D) is measured for various contaminant volume fractions (α). In the no contaminant case (α=0), the C_D shows good agreement with the Moore's theoretical one for a clean bubble. The C_D at the α of O ((10)^<-4>) shows much larger than the one of the purified water, while the C_D at the α of O ((10)^<-6>) shows almost same as the one of the purified water.
一般社団法人日本機械学会の論文
2000-07-31