Characterization of Gas Bubbles Injected into Molten Metals Under Laminar Flow Conditions

Veloci ty and volume m e a s u r e m e n t s of gas bubbles in jec ted into l iquid me ta l s under l a m i na r flow condit ions (at the or i f ice) have been achieved. A novel e x p e r i m e n t a l approach u t i l i z ing no i ses genera ted by bubbles was used to col lec t the n e c e s s a r y data. Argon gas was bubbled through t in, lead, and copper mel t s , and gas bubble fo rma t ion f r equenc i e s (and hence bubble s izes) were de t e rmin e d . It was found that the bubble s ize genera ted for a p a r t i c u l a r or i f ice d i a m e t e r was dependent upon the magni tudes of the o r i f i ce Froude and Weber n u m b e r s . Max imum fo rma t ion f r equenc i e s i n c r e a s e d s l ight ly with dec r e a s i n g or i f ice d i ame te r , and the t r a n s i t i o n point f rom va r y i ng to cons tan t f requency occ u r r e d at an or i f ice Weber n u m b e r of approx imate ly 0.44. Veloc i t ies of gas bubbles r i s i n g through the meta l s were g r ea t e r than those p rev ious ly r epor t ed for s tud ies in which only one bubble was in the mel t at any t ime. Effect ive drag coeff ic ients of the r i s i n g bubbles were found to agree with data p rev ious ly genera ted in aqueous s y s t e m s .