The results of two investigations ore reported. Air bubbles were formed at orifices submerged beneath each of fourteen liquids. The surface tension of the liquids varied from 17.8 to 72.4 dynes/cm., and the viscosities ranged from 0.436 to 713 centipoise. In the first investigation, air bubbles were formed a t orifices at various angles of inclination. Orifice diameters ranging from 0.159 to 0.396 cm. were employed. The air-flow rate was varied from 0.1 to 100 CC.(at standard conditions)/sec. The results were obtained with two different apparatuses by three independent investigators.In the second investigation, the effect of the velocity of a liquid flowing post a horizontal, submerged orifice on the formation of air bubbles was determined. Liquid velocities ranging from 0.34 to 2.5 cm/sec., which spanned the region of laminar flow, were employed. Orifice diameters ranged from 0.15875 to 0.3175 cm., air-flow rates from 0.5 to 100 cc/sec. (at standard conditions).It was found that the bubble formation observed in each of these investigations could be correlated with the physical variobles of the system by the application of Newton's second law of motion to the bubble a t the instant just prior to its release from the orifice.Several chemical processes depend upon contacting a liquid as a continuous phase with a gas as a dispersed phase. The bubbling of a gas in some manner through a liquid is common to these processes. Geddes ( 3 ) attempted to calculate the plate efficiency of distillation columns from the size and number of bubbles contacting the liquid on the distillation trays. This article initiated research on the mechanics of bubble formation. Studies have been made by many investigators of the formation of gas bubbles at horizontal orifices and capillary tubes. However, the early workers neglected the effect of the volume of the chamber upstream from the orifice or capillary tube. Hughes et al. (6) have demonstrated the importance of the chamber volume. At large chamber volumes, the bubbles form at essentially constant pressure, which is usually the region of interest in industrial applications. All investigators observed two regions of formation, constantvolume and constant-frequency. In the constant-volume region, the volume of the bubble is nearly constant and almost independent of the flow rate of the gas. As the flow rate of the gas was increased, the frequency tended to approach a constant. In the constant-frequency region, the volume of the bubbles was proportional to the gasflow rate.Davidson and Amick ( 2 ) have described the different regions of bubble formation for horizontal orifices. The formation observed by the authors was essentialIy the same as that described by Davidson and Amick ( 2 ) . When the orifice was in the horizontal position, the shape of the bubbles was spherical at low flow rates, and at higher flow rates the bubble became elongated in the direction perpendicular to the orifice. At other angles, the bubbles were spherical at low flow rates and gradually assumed a hemispherica...
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