乱流遷移による放射状自由液膜流のせん孔現象 : 流体工学 , 流体機械

The perforation mechanism of a radial liquid sheet, which depends on the Reynolds number, is clarified. The radial liquid film flow 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 when the Reynolds number exceeds a critical value. The transition begins to result in perforation. In this study, the authors formulate a stochastic relation between a void fraction at a reference point and a rate of perforation generated upstream of the point. The radial distribution of the peforation rate is calculated from the void fraction which is measured with a perforation sensor at each radial position. The calculated perforation rate revealed that while the perforation occurs at far downstream of the transition point at relatively low Reynolds number, it does immediately after the transition at extremely high Reynolds number.