Model experiments on two-phase flows occurring in the continuous casting process

We present model experiments with low melting point liquid metal two-phase flows using the setup of the Mini-LIMMCAST facility at HZDR. Argon gas was injected at the tip of the stopper rod. The flow field and the gas distribution were measured in the submerged entry nozzle (SEN) and in the mould by means of electromagnetic and/or ultrasonic techniques. Data sets were recorded for the pressure at the gas injection point and for the levels of the liquid metal surface in the tundish and the mould, respectively. The investigations showed that not all the gas injected forms bubbles or slugs within the SEN. In all likelihood, gas layer were formed around the stopper rod and a part of the gas escapes along the stopper rod towards the free surface in the tundish. The flow experiments delivered a strong indication for the occurrence of a slug flow inside the SEN manifested by simultaneous, coherent oscillations of the pressure at the injection point and the liquid metal level in the mould. Further systematic experiments are necessary to figure out the occurrence of different flow regimes in the SEN depending on the ratio of liquid and gas flow rates.