Effects of injection modes on the flow pattern and temperature distribution of molten steel in a bloom casting mould

Based on an idea that the flow pattern of molten steel in a mold can be controlled by changing the direction of jet from the outlets of a submerged entry nozzle (SEN),a new type of quad-furcated SEN with outlets in tangential direction was designed for bloom casting.The flow patterns and temperature distributions of molten steel in the mold were computed by hydrodynamic models under the conditions of single straight SENs,quad-furcated SENs with outlets in radial direction,and quad-furcated SENs with outlets in tangential direction.For the latter,a strong horizontal swirling flow has been observed along with the upper and lower back flows in the mold.The horizontal swirling flow pattern in the mold can not only reduce the impingement depth of molten steel,inhibit liquid level fluctuation and accelerate inclusion floatation,but also be beneficial to dissipation of steel superheat.Compared to quad-furcated SENs with outlets in radial direction,the jet impingement on the initial shell can be obviously reduced and the cross-section solidified shell distributes uniformly in the mold.Additionally,the horizontal swirling flow pattern moves the hot spot upward in the mold and leads to a 2 to 6 ℃ temperature rise of molten steel around the free surface,which is beneficial to quick melting of mould powder.