In continuous casting,the argon blowing at the tundish upper nozzle is usually used to prevent nozzle clogging,whose effect is closely related to the migration of argon bubbles and the flow behavior of the liquid stee...In continuous casting,the argon blowing at the tundish upper nozzle is usually used to prevent nozzle clogging,whose effect is closely related to the migration of argon bubbles and the flow behavior of the liquid steel in the nozzle.Here,to investigate the effects of argon blowing at the tundish upper nozzle on multiphase flow behavior in nozzle,a threedimensional model of the tundish–nozzle–mold was established for numerical simulation.The results indicate that the argon bubbles injected from the inner wall of the tundish upper nozzle first move downward along the nozzle wall under the action of the liquid steel.As the distance from the tundish upper nozzle increases,the argon bubbles gradually diffuse to the center of the nozzle.Compared with no argon blowing,the liquid steel velocity increases in the center of the nozzle and decreases near the wall with argon blowing.With increasing the argon flow rate,the concentration of bubbles in the nozzle increases,and the process of bubble group diffusion to the center region of the nozzle speeds up.This in turn increases the liquid steel velocity at the center of the nozzle but reduces near the wall.With increasing the casting speed,the concentration of bubbles in the nozzle decreases,the length of the bubble group near the nozzle wall is extended,and the liquid steel velocity at the center region and near-wall region of the nozzle increases.The mechanism of argon blowing at the tundish upper nozzle to prevent nozzle clogging is mainly realized by the isolation effect of the argon bubble group on the inner wall of the nozzle.展开更多
The structure of SEN and upper nozzles was optimized and simulated. Relevant trials were conducted on site during thecasting of Al-killed steel. These optimizations effectively solve the nozzle clogging and reduce the...The structure of SEN and upper nozzles was optimized and simulated. Relevant trials were conducted on site during thecasting of Al-killed steel. These optimizations effectively solve the nozzle clogging and reduce the defects of the casting slab.展开更多
应用FLUENT软件对二维的亥姆霍兹喷嘴自振射流进行了模拟,并以此为基础研究了上喷嘴出口凸出部深入振荡腔对亥姆霍兹喷嘴自激振荡特性的影响。结果表明,上喷嘴的出口凸出部长度和喷嘴壁厚度都对自激振荡特性产生显著的影响。长度为0~0.1...应用FLUENT软件对二维的亥姆霍兹喷嘴自振射流进行了模拟,并以此为基础研究了上喷嘴出口凸出部深入振荡腔对亥姆霍兹喷嘴自激振荡特性的影响。结果表明,上喷嘴的出口凸出部长度和喷嘴壁厚度都对自激振荡特性产生显著的影响。长度为0~0.15 D 1时,自振射流的脉动幅值可以提高20%~80%,提升幅度在射流速度较低时更大;凸出部长度为0.15~0.25 D 1时,射流振幅的提升逐渐降低;长度0.25~0.3 D 1时,射流振幅比普通喷嘴更低,稳定性下降;长度超过0.3 D 1时自振射流会完全消失。凸出部分喷嘴壁厚度在0<δ<0.1D 1范围内对射流性能几乎没有影响,但随着厚度δ的不断增大,性能会减弱,δ>0.15D 1时无法形成自振射流。总之,上喷嘴出口凸出可改善射流振荡性能,但长度和厚度需在一定范围内,否则无法产生自振射流。展开更多
基金the National Natural Science Foundation of China(Nos.51874215 and 51974213).
文摘In continuous casting,the argon blowing at the tundish upper nozzle is usually used to prevent nozzle clogging,whose effect is closely related to the migration of argon bubbles and the flow behavior of the liquid steel in the nozzle.Here,to investigate the effects of argon blowing at the tundish upper nozzle on multiphase flow behavior in nozzle,a threedimensional model of the tundish–nozzle–mold was established for numerical simulation.The results indicate that the argon bubbles injected from the inner wall of the tundish upper nozzle first move downward along the nozzle wall under the action of the liquid steel.As the distance from the tundish upper nozzle increases,the argon bubbles gradually diffuse to the center of the nozzle.Compared with no argon blowing,the liquid steel velocity increases in the center of the nozzle and decreases near the wall with argon blowing.With increasing the argon flow rate,the concentration of bubbles in the nozzle increases,and the process of bubble group diffusion to the center region of the nozzle speeds up.This in turn increases the liquid steel velocity at the center of the nozzle but reduces near the wall.With increasing the casting speed,the concentration of bubbles in the nozzle decreases,the length of the bubble group near the nozzle wall is extended,and the liquid steel velocity at the center region and near-wall region of the nozzle increases.The mechanism of argon blowing at the tundish upper nozzle to prevent nozzle clogging is mainly realized by the isolation effect of the argon bubble group on the inner wall of the nozzle.
文摘The structure of SEN and upper nozzles was optimized and simulated. Relevant trials were conducted on site during thecasting of Al-killed steel. These optimizations effectively solve the nozzle clogging and reduce the defects of the casting slab.
文摘应用FLUENT软件对二维的亥姆霍兹喷嘴自振射流进行了模拟,并以此为基础研究了上喷嘴出口凸出部深入振荡腔对亥姆霍兹喷嘴自激振荡特性的影响。结果表明,上喷嘴的出口凸出部长度和喷嘴壁厚度都对自激振荡特性产生显著的影响。长度为0~0.15 D 1时,自振射流的脉动幅值可以提高20%~80%,提升幅度在射流速度较低时更大;凸出部长度为0.15~0.25 D 1时,射流振幅的提升逐渐降低;长度0.25~0.3 D 1时,射流振幅比普通喷嘴更低,稳定性下降;长度超过0.3 D 1时自振射流会完全消失。凸出部分喷嘴壁厚度在0<δ<0.1D 1范围内对射流性能几乎没有影响,但随着厚度δ的不断增大,性能会减弱,δ>0.15D 1时无法形成自振射流。总之,上喷嘴出口凸出可改善射流振荡性能,但长度和厚度需在一定范围内,否则无法产生自振射流。
