| In modern continuous casting process, submerged entry nozzle (SEN) has been widely used, whose structural parameters and operating parameters affect the surface qualities and internal structure of the bloom by influencing the flow field and temperature distribution of molten steel in mold. So it is of great importance to study SEN.This paper based on studying a bloom mold of the No.1 Steel Plant of WISCO. According to the similarity theory, a water model in the ratio of 1 to 1 has been established. Applying tracing and photographing technology in the experiment, we studied the flow field in mold when different nozzle, such as the single-outlet-hole SEN, four-outlet-hole SEN, five-outlet-hole SEN and eight-outlet-hole SEN, is used, including starting M-EMS or not. As a result, the following results were found:l.When the immersion depth is hi~li2, the trumpet nozzle with single outlet hole is better than the straight nozzle with single outlet hole. When the former was used in casting, the impingement depth is shallower and the uniformity effect of temperature and component is better, at the same time, the heat center is upper which is propitious to the melt of mold powder, and then high quality bloom is acquired.2. The flow field in mold is not symmetrical because the four outlet holes' axes of the primary nozzle with four holes is not vertical. Observing from inner arc side, the vortex appeared in left behind corner and right forward corner in liquid surface. The reasonable operating parameters of the primary SEN with four holes is that setting angle is 2~ 3,the immersion depth is h3 10mm.3. Compared with the primary nozzle with four holes , the improved funnel nozzle with five holes increased the impingement depth, which is not benefit for the inclusion floation.4. When we used the nozzle of eight holes in casting, even the immersion depth is h5, the surface fluctuation of liquid steel is still 2mm and there are some vortexes, which easily arosed entrapping slag.5. The optimum parameters for the new nozzle with four holes include that the nozzle's outlet area ratio is S3, inclination of the SEN is 3 2, setting angle is 3 and the immersion depth is h2 10mm. Compared the new nozzle with four holes with the primary nozzle with four holes and the unproved nozzle with five holes, the former uniformity time decreased 1 second and 0.54 second, the impingement depth lowered 19.7mm and 31.4mm, the response time of surface reduced 0.92 second and 1.55 seconds, and the surface fluctuation of liquid steel is merely equal.6. When the flow velocity in the meniscus region is 0.30-0. 60m/s, the intensity of M-EMS is reasonable. In this experiment, the requisite power is 0.4-1. 2 W. In view of the mold being acontinuous reactor, the input power about 1.2W was selected.7. When the M-EMS was started, the optimum parameters for the primary nozzle with four holes are similar to the former parameters.8. When the M-EMS was started, The optimum parameters for the new nozzle with four holes includes that the nozzle's outlet area ratio is S2, inclination of the SEN is 3 2, setting angle is 4 and the immersion depth is h3-h4. Compared this optimum level with that of the primary nozzle with four holes, the former uniformity time decreased 5.63 ~ 9.33 seconds, the protuberance height of the surface of liquid steel lowered 0.83 ~ 1.03mm, the surface fluctuation of liquid steel reduced 1.17 ~ 1.2mm, and the impact-point and the flow velocity in the meniscus region is almost equivalent. It could be concluded that the percentage of equiaxial crystal would increased when the new nozzle with four holes is used in casting.
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