FLUID FLOW CHARACTERISTICS AND RTD ANALY

The mathematical modelling of the fluid flow and heat transfer behaviour of the steel melt in the tundish is carried out for a single strand tundish. The flow dynamics and heat transfer in the tundish is analysed by presenting the velocity field, Residence time distribution (RTD) curves and the temperature profiles by changing the geometrical parameters such as the width, the bath height, their simultaneous change and the nozzle distance of the tundish. The RTD curve is used to find the different volumes such as plug volume, dead volume and mixed volume inside the tundish. The ratio of mixed to dead volume, which indicate the mixing capability of a tundish, is estimated. Heat transfer analysis is carried out under steady state conditions for the constant heat fluxes from walls and from free surface of the tundish, for the above mentioned parametric changes so as to find out tundish steel melt cooling rates to determine the lowest temperature zones (maximum cooling), which are the indications of the dead volume regions during the steel flow. It is observed that the increase in the dead volume fraction proves detrimental for mixing. The value of the dead volume is found to be more sensitive than the other two volumes to find mixing capability and hence important to reduce this stagnant portion as far as possible. It is concluded that the validation presented for the two cases is quite satisfactorily close to the experimental observations reported in the literature.