Water Model Experimental Research On Effect Of Swirl Blade On Flow Pattern And Bubble Behavior In Up-hill Teeming Process

The uneven distribution of flow field during the uphill teeming process may lead to,large number of gas entrapment into the molten steel,excessive erosion on the runners by the molten steel,molten steel splashing and slag entrapment in the mold.Consequently,the risks of porosity,exogenous nonmetallic inclusion generation and secondary oxidation increase,and thus the internal and external quality of the ingots decreases.Previous research results show that a swirl blade set up in runner in the uphill teeming process can improve the flow field greatly.However the effects of the structural parameters of the swirl blade on the bubble behavior in the runner and mold are not investigated comprehensively.In this study,water model experimental research is conducted.The effects of the swirl blade structural parameters and set up position on the fluid flow pattern and bubble behavior in the central runner,the horizontal runner,the vertical runner and the mold are investigated.The behavior of the bubble that blowing into the end runner brick is also observed with swirl blade in vertical runner.The following main conclusions are obtained.(1)With the increase of the twist angle and the thickness of the swirl blade set up in the central runner,the depth of gas-liquid interface in the central runner decreases gradually both.The largest decrease can reach 44.4%and 39.8%,respecti'vely,compared with that of no blade case.The impinge of the fluid on the vertical wall of the end runner brick in horizontal runner is gradually reduced with the increase of swirl blade twist angle,the largest decrease can reach 59.7%comparing with that of no blade.With the increase of swirl blade thickness,the impinge is slightly increased.However the largest decrease can reach 43.9%compared with that of no blade.(2)Without swirl blade in the vertical runner,only one hump and one mainstream are formed in the mold.With swirl blade,two humps and two mainstreams are formed on both sides of the swirl blade,these two mainstreams flow out of the vertical runner in different directions and impacts on the mold wall separately.On the whole,the fluid impact on the mold wall is reduced with swirl blade.With the increase of the swirl blade angle,the bubbles at left and right sides of the swirl blade in the mold is more uniform.(3)?H(the height difference between the hump and the water surface)in the mold with swirl blade at vertical runner,? H decreases with the increase of the twist angle and the decrease of the thickness of the swirl blade,the largest ?H decrease can reach 65.4%and 41.1%,respectively.(4)The orientation relationship between the horizontal runner and the bottom edge of swirl blade has great influence on the flow field and bubble behavior:the parallel placement of swirl blade edge with the runner is better than the perpendicular case or no swirl blade case.(5)In the case of gas blown from the end runner brick,most of the bubbles deformed in area One(the area 5mm below the bottom edge of the swirl blade).The bubble break can be observed in area Two(the area between the swirl blade center in height and the bottom edge of the swirl blade)in all bubble diameter cases in this study.With the increase of the bubble diameter,it is observed that the bubble merge area becomes larger and the number of bubble merged increases at the vertical runner.