308 放射状自由液膜流の乱流遷移による液膜穿孔過程の微視的観察(S42-1 流れの可視化実験解析(1),S42 流れの可視化実験解析)  [in Japanese] 308 Observation of perforation process of a radial liquid sheet induced by laminar-turbulent transition  [in Japanese]

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 1-4□m thickness partly and turbulence at the edge of the thin liquid sheet triggers the perforation.