The mold is one of the core components of steelmaking, and its flow field distribution will directly affect the quality of the casting slab. A three-dimensional nozzle model is built in this work, and fluid simulation is carried out to investigate the influence of the casting speed, immersion depth, slab thickness, and width on flow behavior in the mold. This model combined simulation with real conditions. The casting speed, immersion depth, slab width, and slab thickness are the actual process parameters used in the steel factory. The results show that when the casting speed increases from 0.6 to 1.0 m/min, the strike positions of the narrow surface are 0.439, 0.476, and 0.480 m below the liquid level, respectively. When the immersion depth increases from 180 to 220 mm, the impact depth of the stream at the exit of the nozzle side hole moves down, the lower recirculation zone moves to the centre and bottom of the slab, and the upper recirculation zone moves downward. When the slab thickness increases, the strike locations of the narrow face move down. Further, when the slab width increases, the distance of the strike location from the strike position increases first and then decreases. From the fluid results, the process parameters can be optimized by considering the strike location and the change of the surface turbulent kinetic energy. The model proposed in this work provides a theoretical guidance and optimization for the nozzle.

Protective slag is coated on the surface of molten steel during continuous casting, the flow and heat transfer state of the protective slag is a decisive factor affecting the inflow and consumption of liquid slag and is also an important prerequisite for stabilizing and improving the quality of continuous casting billets. Based on the Navier Stokes fluid momentum conservation equation and energy equation, a two-dimensional longitudinal numerical model describing the flow/heat transfer of liquid protective slag on the surface of steel is established. The data comes from the equipment parameters and casting process of an arc shaped slab continuous casting machine in a domestic steel plant. The flow field and temperature field distribution of protective slag are calculated and analyzed, and the effects of factors such as slag layer thickness and shear speed on the flow and heat transfer status of the liquid slag layer are discussed. When the bottom shear velocity increases from 0.005 m/s to 0.2 m/s, the maximum flow velocity of liquid slag from the nozzle to the narrow surface in the center area of the model increases from 0.0012 m/s to 0.0617 m/s, and the average longitudinal flow velocity of liquid slag near the nozzle increases from 0.0012 m/s to 0.0627 m/s. The research results provide reference for investigating the complex metallurgical behavior of protective slag.

During the steel continuous casting, the submerged entry nozzle (SEN) plays a crucial role in the fluid characteristic of fluid steel, which further affects the slab quality. In this paper, a nozzle model is developed to study the influences of nozzle inclination, nozzle area ratio, and side hole aspect ratio on the fluid characteristic of fluid steel. The results show that when the nozzle angle increased from 10° to 20°, the impact points of the narrow surface were 0.402 m, 0.476 m, and 0.554 m away from the meniscus, respectively. In addition, when the nozzle area ratio increased from 0.96 to 1.16, it resulted in a significant decrease of the speed of high-temperature liquid steel flowing out of the nozzle. Moreover, when the side-hole aspect ratio was 1.47, the maximum turbulent kinetic energy of the free surface reached 0.00141 m² s⁻². Furthermore, when the aspect ratio was 1.67 and 1.84, a slight difference existed, and the maximum turbulent kinetic energy was almost 0.00095 m² s⁻². The proposed model can provide theoretical basis and guidance for nozzle optimization.

Steel is mainly produced through continuous casting; molten steel flows into the mold from the tundish, where it cools and then enters the secondary cooling zone, ultimately solidifying into a billet. During the continuous casting production process, the quality of the casting billet is mainly related to the lubrication state of the coated slag. In the upper part of the mold, the consumption of liquid protective slag directly affects the friction state of the initial solidified billet shell. Therefore, the flow and fluctuation characteristics of coated slag in the meniscus area are very important. There is limited research on the flow and fluctuation characteristics of coated slag in the meniscus area, and little consideration has been given to the shape of the meniscus. In this work, a two-dimensional numerical model for the flow and fluctuation of coated slag in the meniscus region was established, and the transient flow velocity of protective slag and molten steel at each moment of the vibration cycle was obtained, as well as the fluctuation of the slag/steel interface in the meniscus region. The results show that when the surface mold vibrated upwards, the protective slag in the meniscus area flowed clockwise. When the mold moved downwards, the protective slag in the slag pool generated a counterclockwise flow vortex. When the mold was in a positive slip state, the negative pressure formed by the upward flow of the protective slag on the meniscus and the inertia force of steel liquid pushed the meniscus toward the inner wall of the mold. During negative slip, the flow of coated slag generated positive pressure on the slag/steel interface, pushing the meniscus toward the steel liquid, and at the initial moment of negative slip, the steel liquid overflowed into the slag channel. This model could provide a theoretical basis for the flow control of protective slag.

In the continuous casting, the protective slag is coated on the surface of the molten steel, which is an important factor affecting the quality of the billet. The liquid slag layer on the surface of molten steel should be kept at an appropriate thickness to ensure a sufficient supply of liquid slag and to prevent slag from becoming entangled in the billet shell. Moreover, the consumption of protective slag should be appropriate to ensure stable liquid slag film thickness and uniform heat transfer between the casting billet and the mold. In this work, a two-dimensional numerical calculation model using volume of fluid method was established for the flow of protective slag, the Navier–Stokes equation was solved for the model, the consumption of protective slag during a vibration cycle was calculated, and the effects of factors such as casting speed, amplitude, and vibration frequency on the consumption of protective slag were explored. The results showed that when the casting speed increased from 1.2 m/min to 1.6 m/min, the consumption of protective slag per unit area decreased by about 4.76%, but the consumption of protective slag per unit length of the casting billet increased by about 26.98% within a vibration cycle. The consumption of protective slag per unit area and per unit billet length within a vibration cycle increased slightly with the increase of amplitude. The variation pattern of the consumption of protective slag with vibration frequency was not obvious. This model can provide theoretical basis and technical guidance for the design of protective slag, thereby improving the quality of steel billets in steel plants.