Numerical Investigation of Fluid Flow Phenomenon in a Curved Shape Tundish of Billet Caster

Abstract

The conventional delta shaped tundish (rectangular with sloping walls) is currently used in many industries for billet caster. The effective volume in this type of tundish is significantly low and results in a lower quality of steel. In the present work, a three-dimensional mathematical model has been used to study the fluid flow characteristics in a six strand billet caster tundish whose one side is curved. The results obtained were compared with a conventional delta shaped tundish and the strong role of curvature in modifying the fluid flow characteristics is noticed. Investigations were performed to study the effect of ladle pouring point in a curved shape tundish. It was found that fluid flow characteristics can be improved by placing the ladle pouring point at the right position. Simulations have been performed for two different shapes of pouring chamber to investigate the role of curvature in the flow control devices. The results obtained confirmed the strong role of curvature to get the improved characteristics for inclusion flotation. The mathematical model has been validated by the experimental results of Singh and Koria for a single strand bare tundish.KEY WORDS: billet caster tundish; pouring chamber; plug volume; mean residence time; inclusion flotation. distance between two ladle pouring points are 200 mm. Table 2 shows all other operating parameters of the tundish. Two different shapes of flow control devices called Pouring chamber were used for the study. Mathematical Formulation and AssumptionsThe flow field in the tundish was computed by solving the continuity and momentum conservation equation in ISIJ International, Vol. 45 (2005) , Fig. 1(b).Top view of the delta shape tundish about symmetry plane for position-1 of ladle pouring point at position-1 (dimensions are similar to curved shape tundish shown in Fig. 1(a)). Fig. 1(c).Top view of the delta shape tundish in Case 6 of Table 1 for position-1 of ladle pouring point (dimensions are similar to curved shape tundish shown in Fig. 1(a)). Fig. 1(d).Top view of the delta shape tundish for Case 7 in Table 1 for position-1 of ladle pouring point (dimensions are similar to curved shape tundish shown in Fig. 1(a)). Table 1. Simulation performed for following cases. Table 2. Operating parameters of billet caster tundish with six strands. Fig. 2(a).Top view of the contour shape pouring chamber (dimensions in mm). Fig. 2(b).View of the section AB and CD shown in Fig. 2(a) of pouring chamber (all dimensions are in mm).three-dimensional. The standard k-e model was solved to incorporate the turbulence near the incoming and outgoing stream. The free surface of the liquid in the tundish was assumed to be flat and the slag depth was considered to be insignificant. Natural convection effect was neglected while computing the velocity field. The equation for dispersion of tracer in the tundish was solved to capture the variation of tracer concentration in the tundish and then RTD analysis was performed. Here, C 1 ϭ1.44, C 2 ϭ1.92, C m ϭ0.09, s C ϭ1, s k ϭ1, s...

Physical and numerical modelling of a four-strand steelmaking tundish using flow analysis of different configurations

“…A numerical model was also developed in FLUENT to simulate the flow behaviour in the water model, improving the understanding of the results of the physical model experiments. The effect of the assumptions of symmetry and dynamically steady flow on numerical results, which were frequently used in tundish CFD studies to reduce the computational time (Kumar et al, 2008;Tripathi and Ajmani, 2011;Zhong et al, 2007;Mishra et al, 2012;Tripathi and Ajmani, 2005;Jha et al, 2001) was also investigated. This is of importance, as there is no information on the effects of these assumptions on computational accuracy in the available literature on tundishes.…”

“…This allows a single iteration per time step to be used, instead of approximately six to eight iterations per time step, drastically reducing the required computational time. Although both of these assumptions are frequently used in tundish literature (Kumar et al, 2008;Tripathi and Ajmani, 2011;Zhong et al, 2007;Mishra et al, 2012;Tripathi and Ajmani, 2005;Jha et al, 2001), there is little information available about their effect on the numerical results. For this reason, the RTD curves were compared for three different cases: dynamically steady flow with two symmetry planes, dynamically steady flow without symmetry, and fully transient flow without symmetry.…”

Numerical and Experimental Analysis of Flow Phenomenon in Centrifugal Flow Tundish

“…For the free surface, the shear stress boundary (zero shear stress) condition was used. [9][10][11][12][13] At the inlet, the mean vertical average velocity is assumed to be uniform in its transversal section, and it was obtained by dividing the steel flow rate into the transversal area. A value of zero was established for the other two components of velocity.…”

Removal of Inclusions Using Micro-bubble Swarms in a Four-strand, Full-scale, Water Model Tundish

“…Hence, the efficiency of inclusion removal has been one of the most important criteria in evaluating the metallurgical performance of any given tundish design. Numerous studies have been conducted to optimize the designs of tundishes using various flow control devices, [1][2][3][4][5][6][7][8][9][10] such as weirs, dams, impact pads, turbulence inhibitors, etc. In order to promote the floatation of inclusions, these devices can improve the removal of larger inclusions, greater than say 50 μm, but do not necessarily promote the removal of smaller sized inclusions, owing to their extremely low Stokesian velocities.…”