Abstract: A physical model of liquid steel flowing in beam blank casting mold was set at 0.7∶1 geometric similarity ratio, and the influence of response time at different position and liquid surface fluctuation was studied. It was showed that the flow field distribution in the existing through nozzle mould was extremely asymmetric and the response time of each position of the mould was quite different. The percentage of liquid level fluctuation kept within ±3 mm was 96.3 %. The optimal improvement scheme of nozzle (three side hole nozzle) effectively solves the problem of long and inconsistent response time at different positions of the mould, and the percentage of liquid level fluctuation kept within ±3 mm is 99.7 % and within ± 5 mm is 100 %.

Key words: non-equilibrium, beam blank, casting mold, response time, liquid surface fluctuation, flow field