Validation of CFD-calculations for the submerged entry nozzle-mould systemusing the digital particle image velocimetry

The interest in flow-related optimisations in continuous casting is growing as the requirements relating to productivity and quality of the cast produ ct become increasingly strict. By purposefully influencing the flow profile in the submerged entry nozzle-mould system, improvements can be made to th e internal and surface quality of the cast product. On the one hand, the ta sk of these investigations is the optimisation of the flow profile at the m eniscus. On the other hand, the flow beneath the primary vortex should as f ar as possible assume an isokinetic structure in casting direction. In the interest of satisfying these requirements, the examination of flow phenomen a is today part of the daily routine in steelworks. Such examinations are b ased on physical and numerical models, by means of which the nozzle-mould s ystem can be recorded and thus enable direct adaptation of the nozzle shape and process parameters. The validation of numerical models, e.g. CFD (comp utational fluid dynamics) calculation, acquires great significance in this respect. For this reason, flow-related experiments are usually restricted t o water models in the scale of 1:1. The measurement results enable the nume rical simulation for the water model to be validated and there-after be tra nsferred to the flow of the molten steel. To do this, velocity vectors for various process parameters are determined by means of a laser-optical proce dure, known as digital particle image velocimetry (DPIV), and compared with calculated vectors. The nozzle and mould configurations and the process pa r-ameters utilized for this have been freely selected to emphasize the fund amental flow-related effects.