Abstract
Air bubbles were formed in water and in mineral oil by use of single, circular, horizontal, squareโedged orifices facing upward. Twenty orifices were tested, ranging from 0.017 to 0.79 cm. (0.0067 to 0.31 in.) in radius. Incieasms the whime, of the gas chamber below the orifice (over the range of 4 to 4,000 cc.) was found to increase the bubble size. The gasโchamber volume was minimized in most of the work in order to confine attention to the effects of orifice size and gasโflow rate. The liquid containers were large enough to eliminate significant wall effects, and operations were conducted at atmospheric pressure.
The gasโflow rate was varised from about 0.01 to about 250 cc./sec. over the course of the work. At relatively low rates, the orifices generally formed single โstaticโ bubbles, the volumes of which were proportional to the surface tension and orifice radius and independent of the gasโflow rate. At high flow rates the bubble frequency became high and the bubble volume became proportional to the gasโflow rate and independent of the surface tension. The bubble frequency reached a maximum value for each orifice, this value being a function of the orifice radius. For air bubbles in water, the correlation of the maximum bubble frequency, n~m~ bubbles/sec., with the orifice radius, r cm., and the airโflow rate, q cc./sec., was found to be n~m~ = 9.1__q__^0.13^/r^0.43^. The maximum frequencies ranged from about 25 bubbles/sec. for the largest orifices to about 75 bubbles/sec. for the smallest orifices used.
It was found that consecutive bubbles paired or coalesced in definite ways in certain ranges of the gasโflow rate. A description is given of this bubble behavior, based on stroboscopic and photographic observation.