Physical and mathematical modelling of tundish flows using digital particle image velocimetry and CFD-methods

The flow in continuous casting tundishes is considerably responsible for the flotation of non-metallic inclusions and the quality of steel. Because tests in liquid steel can hardly be performed, water model testing considering the geometric and dynamic similarity laws is often used. Here, quantitative investigations with time and cost expensive laser measurement techniques are possible. The digital particle image velocimetry (DPIV) can be seen as a completion and is an effective method to obtain reliable results. DPIV measurements on a 1:4 scaled model of a single strand tundish are carried out which lead to a good interpretation of the dynamic flow phenomena. The flow separates at the bottom of the tundish and a recirculating region develops. Simultaneously, the jet out of the shroud induces a contra-rotating double vortex and a short circuit flow along the side walls. Furthermore, a decreasing water level in the physical model is investigated to simulate the ladle change. The experimental results are used to validate numerical simulations on the basis of the Reynolds equations. In order to describe the turbulence, a two-equation model (realizable k-epsilon model) is used. The results obtained with this model correspond well with the DPIV data. The basic intention of the present investigations is to transfer the numerical simulation of the water flow to the melt flow in the next step. Thus, a high accuracy of the theoretical results can be guaranteed.