PIV Analysis On Flow In The Mold During Continuous Casting Of Steel Slab

High-efficiency continuous casting has become the main development direction of the continuous casting. Fluid flow in the mold must be optimized in order to improve the internal and surface quality of the cast and avoid steel leaking while increasing the casting speed. In this paper, PIV (Particle Image Velocimetry) is used to study the fluid flow phenomena in continuous casting of steel. The paper describes fundamental principle of PIV as well as its hardware (laser, CCD etc.) and software system (image gathering system, image processing system). Suitable seeding particle and software setting parameters are found for the slab physical simulation experiment. Flow visualization in the mold is well achieved.Physical model system for continuous casting of slab with the size of 1650mm×220mm is designed, including mold model, water circulation system, AC (alternating current) sheet light system. The influence of nozzle angle, nozzle diameter, immersed depth of nozzle, pit structure of nozzle and the casting speed on the flow behavior are investigated quantitatively. The results have shown that: (1) There are two large re-circulations above and below of fluid jet in the mold separately, and the below vortex is larger than the above one. The slab quality is closely related with these two vortexes. (2) The angle and immersed depth of nozzle are two important factors which influence the flow in the mold. As for the simulating model, the suitable immersed depth is chosen about 130mm. The bigger the angle is, the lower the impacting point on the narrow face. (3) The higher the casting speed is, the higher the impacting point of the jet stream on the narrow face. Furthermore, higher casting speed will bring serious fluctuation to meniscus, accordingly it will lead to various defects. (4) The diameter and the outlet area as well as the pit structure of the nozzle have certain effects on the flow in the mold.