连铸结晶器物理模拟中吹气量的相似转换

Similarity transformation of gas blowing rate in physical simulations of continuous casting molds

依据相似原理,考虑了气液流动之间的相互影响和实际吹氩时的高温膨胀,采用修正弗劳德准数对现场吹氩量和实验吹气量之间进行相似转换,并推导出四种常用的模拟气体与现场吹氩量之间的换算关系.以断面为210mm×900mm的结晶器为原型,采用0.6∶1的缩小水模型对现场实际工况条件进行模拟.结果表明,模拟与现场情况能够较好的吻合.当模型水流量为3.80m3.h-1、吹气量为0.93L.min-1时,气泡在结晶器内分散均匀,气泡逸出不会造成过大液面波动;当水流不变、吹气量增加到2.79L.min-1时,气泡聚集在水口周围上浮,水口周围波动剧烈,渣层出现裸露.模拟现象与现场浇注现象的相似性验证了吹气量相似转换的正确性.

Based on the similarity theory,the interaction of fluid flow and gas flow in gas-liquid two-phase flow and the expansion of argon in actual continuous casting were taken into account,and the relation between argon flow rate in a plant and gas flow rate in experiment was established by modified Froude numbers. The transformation formulas of flow rate between four kinds of simulation gases and argon in a plant were obtained. A 0.6：1 scale water model was undertaken to simulate the technological process in a prototype with the cross section of 210 mm×900 mm. The results show that the experimental phenomena agree well with the practical ones. When the water flow rate is 3.80 m3·h-1 and the gas flow rate is 0.93 L·min-1 in modeling,bubbles do not lead to excessive level fluctuation due to their relatively homogeneous dispersion in the mold. When the water flow rate is 3.80 m3·h-1 and the gas flow rate is 2.79 L·min-1,most bubbles float up in the vicinity of the submerged entry nozzle and there is strong fluctuation around the submerged entry nozzle,so opening of slag layers occurs in the mold. The correctness of similarity transformation of gas flow rate was validated with consistencies between simulation results and practical phenomena.