Non-uniform gas bubble distribution remains a major constraint to improving refining efficiency in Ruhrstahl-Heraeus (RH) processes. In this study, a 1:4.8 scale water model based on a 80-ton RH furnace was developed to investigate the influence of gas-blowing nozzle deflection angles on flow behavior and refining performance. Both horizontal (α) and vertical (β) deflection angles were systematically evaluated in terms of their effects on circulation flow rate, bubble behavior, flow field characteristics, decarburization efficiency, mixing efficiency and liquid level fluctuation. The results show that the gas blowing nozzle with a horizontal deflection angle can generate a swirling flow in the up-snorkel, which promotes bubble breakup and the formation of small bubbles. Meanwhile, the swirling flow condition enhanced mixing behavior near the ladle surface and the snorkel inlet, while it had limited impact on the stagnant region near the ladle bottom. When α was equal to 20 deg, the RH system showed a better overall performance, compared with the conventional radial injection scheme (α = 0°). Specifically, the circulation flow rate was increased by 6.84 pct, and the decarburization time was reduced by 7.00 pct. Furthermore, the Sauter mean diameter was decreased by 6.82 pct, which indicated an improved gas-liquid interaction. Moreover, liquid level fluctuations in the vacuum chamber were reduced by 29 pct. Combined with a vertical deflection angle β at the condition of α = 20 deg, the swirling flow was weakened. This reduced bubble dispersion and led to the formation of larger bubbles, ultimately lowering both circulation flow rate and refining efficiency. In summary, the swirling flow scheme with a horizontal nozzle deflection angle of 20 deg provided the most favorable outcomes in terms of bubble dispersion, flow uniformity, and refining efficiency.
