Effects of injection modes on the flow pattern and temperature distribution of molten steel in a bloom casting mould
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摘要: 依據改變水口側孔射流方向來控制結晶器內鋼流流動狀態的思想,設計了一種大方坯連鑄結晶器新型四分切向水口.對不同類型水口(直通式、四分徑向以及四分切向水口)澆注條件下大方坯連鑄結晶器內鋼水流動形態和溫度分布狀況進行了流體動力學比較研究.結果表明,新型四分切向水口不僅可以使結晶器內鋼水形成上、下兩個回流,并能夠產生較強的水平旋流.該水平旋流能降低鋼水的沖擊深度,抑制鋼液面波動,促進夾雜物上浮,還具有促進鋼水過熱耗散的效果.與四分徑向水口相比,新型四分切向水口能減弱射流對初生坯殼的沖擊,均勻橫截面坯殼厚度.此外,該旋流狀態使熱中心上移,自由液面附近鋼水的溫度可提高2~6℃,改善化渣條件.Abstract: 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.
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Key words:
- blooms /
- continuous casting /
- molds /
- nozzles /
- swirling flow
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