Abstract: Gas bubbles’ size, their distribution and flow behavior in tundish have been investigated at different conditions of argon blowing through long shroud in continuous casting in water model experiments. The experimental results show that in the lower water flowrate range (≤2.4 m3/h), 0.11 mm diameter gas nozzle produces above 60 % proportion of tiny bubbles (0.1－0.5 mm), 0.25 mm diameter gas nozzle 45 %, and 0.58 mm diameter nozzle about 35 %. The proportion of larger bubbles (>1.0 mm) produced with the 0.58 mm diameter gas nozzle is maximal. The proportion of tiny bubbles (0.1－0.5 mm) formed with a 0.25 mm diameter single hole nozzle and a diameter 0.25 mm double-hole nozzle is more than 80 % when the water flowrate is 3.0 m3/h. In the lower water flowrate (≤2.4 m3/h), the proportion of tiny bubbles formed with the two nozzles is similar, but the proportion of larger bubbles (>1.0 mm in diameter) produced with the diameter 0.25 mm double-hole nozzle is smaller than that with the diameter 0.25 mm single hole nozzle and the double-hole nozzle produces larger number of bubbles. The action area of gas bubbles in tundish without a turbulence inhibitor is larger than with a turbulence inhibitor.

Key words: continuous casting, long shroud, argon blowing, gas nozzle, fluid flowrate, bubble diameter distribution, bubble flow behavior