No abstract

No abstract

The present study shows the results of visualization experiments of the jet formation through a dynamic model of the human vocal folds. The model consists of two counter-rotating, 3D-shaped driven cams covered with a stretched silicone membrane. The 3D contours of the cams are a result of an optimized mapping of observed characteristic clinical vocal fold motions. The experiments are performed by using cams which produce the convex, triangular, rectangular, and concave or sand-glass regular glottis closure types. Two irregular cases are investigated: one of the convex cams is statically closed or opened. These cases cause an oscillating jet which attaches to the ventricular folds and appears to change the part of the aero-acoustic sound spectrum induced by vortices.

No abstract

The free falling liquid steel jet behavior is numerically investigated using implicit large eddy simulations (ILES) and the volume of fluid (VOF) approach. The research is focused on primary breakup phenomena near the nozzle using the standard open-source computational fluid dynamics library OpenFOAM. To quantify the influence of process and constructional parameters exclusively for the structure of a free falling liquid steel jet, several central conditions are explored. The calculations concentrate on disturbances at the nozzle inlet due to adverse inflow conditions. The jet behavior is caused by an asymmetrical lift of the stopper rod and a liquid steel rotation in the tundish based on the magnetic heating process, which is transported into the nozzle due to the conservation of angular momentum. The calculations with adjusted rotation show distinct influences with developing structures like helix or hollow-cone-shaped jets. Differences are observed based on the nozzle type. In particular, a tube nozzle (constant diameter) and an industrial nozzle setup (divergent-convergent shape) are investigated. The inflow conditions have a large influence on the tube nozzle, where the outflow is delayed and the jet disintegrates. However, the industrial nozzle type shows less impact, but the jet surface is in general more corrugated and disturbed.