Modeling of Initial Mold Filling with Utilization of Swirl Blades

Abstract

The flow pattern in the uphill teeming process has been found to be closely related to the quality of ingots regarding the formation of non-metallic inclusions and entrapment of mold flux. The filling conditions can be improved by the utilization of a swirl blade in the runner. The emphasis of this study is to investigate the flow pattern of steel in the gating system and molds with swirl blades implemented at the bottom of the vertical runners during the initial stage of the mold filling process based on the authors' previous study. A two-mold gating system was adopted in the study and different orientations of the swirl blade were studied. In addition, same calculation method and boundary conditions were used to study the flow pattern in the uphill teeming. The results show that more calm filling conditions with less fluctuations are achieved in the molds with the implementation of swirl blades. However, a chaotic initial filling condition with a considerable amount of droplets is created when steel enters the molds. In addition, the orientation of the swirl blades affects the flow pattern of the steel. From the current results it is clear that a parallel placement of the swirl blade is better than a perpendicular placement of the swirl blade. Moreover, the fluctuations of the hump height decrease as the filling proceeds. In addition, the implementation of swirl blades can decrease and stabilize the wall shear stress value in the gating system.

Effect of TurboSwirl Structure on an Uphill Teeming Ingot Casting Process

“…This is really expected for the teeming process to lead to a lower initial velocity to the mold and to lower the hump height. [11] In Figure 16, all the swirl numbers are >2 when the flaring angle is <60 deg. This means that there is a strong rotation, since the wall had a weak effect on the liquid steel, i.e.…”

“…[10] The direction at which the swirl blade is placed in the vertical runner can also affect the flow pattern, and the use of a swirl blade can decrease and stabilize the wall shear stress. [11] However, a swirl blade is always quite difficult to manufacture, and when it is inserted in the gating system, there is a risk that the runner will be clogged. This may also bring in a new inclusion to the liquid steel before solidification.…”

“…The finite element analysis software, COMSOL Multiphysics Ò , was chosen for the simulation due to its good adaptability for dealing with the coupled phenomena, such as thermal shock and heat transfer, which must be included in the subsequent research. Some researchers have used the k-e based turbulence models to investigate the swirling flow, [7][8][9][10][11][12][13]19,20] but the CFD module of COMSOL has only one type of k-e based turbulence model, the standard k-e turbulence model. Some papers have reported that the standard k-e turbulence model often shows poor agreement with experiment data.…”

An Experimental and Numerical Study of Swirling Flow Generated by TurboSwirl in an Uphill Teeming Ingot Casting Process

“…Throughout the years, many researchers have investigated this technique by numerical and physical modelling. [5][6][7][8][9][10] When using a swirl blade, there is a risk of introducing new inclusions to the liquid steel due to the high wall shear stress inside the refractory wall. The manufacturing process of the swirl blade is also rather complicated, which reduces its application.…”

“…24) Furthermore, it has already been used to analyse the swirling flow generated by the swirl blade. [6][7][8][9][10]15) However, some published work simulating the turbulent swirling flow for a gas cyclone 25) and tundish 13,14) found that the Reynolds stress model (RSM) 26) can simulate the swirling flow most accurately compared to the experimental results. The numerical simulation part of this work used all three turbulence models above to test which one that best could describe the swirling flow more precisely, especially for the air-core vortex.…”