Application of image analysis for the measurement of liquid metal free surface

During the induction melting and stirring of molten metal a meniscus forms on the surface of the bath. This phenomenon affects the processes occurring on the metal-gas interface since they change the size of the real free surface of the metal. Numerical simulations indicate a significant scale of the phenomenon during typical processes of the induction melting of metals. Experimental measurements of the real free surface of induction melted metals can be quite difficult because of the rapid changes in the surface shape and high temperature of the molten metal. Therefore, a fast non-contact method with the use of laser and image analysis was proposed. However, in the case of liquid metals an optical method of measurement has its limitations as many molten metals shine. The problem was resolved by the use of a green laser and a narrow-band optical filter. This paper presents the methodology and problems of meniscus shape non-contact measurements.