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Synthetic jets perpendicular to the mainstream have been used to experimentally study the coaxial jets mixing enhancement in this paper. The parameters of coaxial jets such as vorticity, streamwise velocity, radial velocity, Reynolds shear stress, and turbulence intensity are measured using the particle image velocimetry (PIV) and hot wire anemometers. The distribution characteristics of these parameters with and without synthetic jets were obtained. The mechanism of coaxial jets mixing enhancement using synthetic jets was summarized by analyzing these experimental results, and it was also found that the momentum coefficient was the most critical factor for jets mixing enhancement. The comparative experiments fully verified the mechanism, showing that with an appropriate momentum coefficient, the synthetic jets significantly enhanced coaxial jets mixing.

This paper reports on the re-engineering of standard five-strand tundish designs into a five-strand asymmetric tundish, which resulted in a non-uniform rate and bias for each strand. We sought to improve the casting conditions by optimizing the liquid steel flow-field in the tundish. Both a water modelling experiment and a numerical simulation were performed to analyze the flow-field according to various diversion hole diameters and injection angles. The results showed that the average residence time decreased as the diameter of the diversion holes increased. As the injection angle was increased, the average residence time initially decreased and then increased. The liquid steel from the ladle shroud rapidly extended to the #2 and #3 strands in the original tundish, which reduced the likelihood of inclusion collision and coalescence.