Abstract
The perforation process of a radial liquid sheet is clarified. The radial liquid sheet is generated by a water discharge through a small gap formed between the end of a nozzle and the flat surface of a disk. The liquid film flow spreads radially outward on the disk, flowing from the edge of the disk into the air as a liquid sheet. Sudden laminar-turbulent transition occurs in the liquid sheet. The transition leads to perforation of the liquid sheet. The authors observed the perforation process with a CCD camera providing high temporal and special resolution images. The observation reveals that three dimensional development of disturbance waves appearing on the liquid sheet produces very thin liquid sheets of 1-4μm thickness partly and turbulence at the edge of the thin liquid sheet triggers the perforation.
