Bubble Formation from Single Nozzles in Liquid Metals

Studies have been made on the formation of bubbles in mercury and in liquid silver by using a single silica nozzle facing upward. Nozzles used in the experiments are of the sizes 0.22–0.82 cm in O.D. and 0.10–0.30 cm in I.D. The gas-chamber volume Vc and the gas-flow rate Vg are varied from 0.15 to 200 cc and from 0.0167 to 70 cc/set, respectively. The size of bubbles is determined from the frequency of bubble formation and the gas-flow rate. The observed bubble size is compared with that calculated from theoretical or experimental equations obtained for wetted nozzles. The experimental values of bubble size do not agree with the values calculated using the inner diameter of the nozzle. On the other hand, when the non-wettability of the nozzle in liquid metals is taken into account and the outer diameters are adopted as the nozzle diameters in the equations, close agreement between the experimental and calculated results is obtained. Thus, it is shown that the quantitative estimation of the size of bubbles formed from a single nozzle in liquid metals is possible.