Experimental Investigations on Spray Characteristics of Water-Air Nozzles

In the secondary cooling zone of the continuous casting process, the steel is cooled down by water and water-air nozzles. The cooling has to be sufficiently intensive to ensure a certain shell thickness and the controlled solidification of the strand. Furthermore, a controlled and uniform cooling strategy is important to minimize the amount of defects in the solidified steel. To determine the cooling characteristics of different nozzles at different operation parameters, the Nozzle Measuring Stand (NMS) at Montanuniversitaet Leoben is used. In the first part of this work, the measuring principle of the NMS is explained. Secondly, the influence of different cooling parameters is discussed. The water distribution (WD) and the heat transfer coefficient (HTC) for a single nozzle type have been measured using the NMS. To show the change in cooling intensity over the width of the spray, the HTC has been determined in several positions. Of particular interest is the area of overlapping of the spray cones. The modified process parameters for this investigation are the water flow, air pressure, and casting velocity.