Investigation on the Partial Coalescence and Vortex Ring Phenomena of Drop Impact onto Deep Liquid

• Main Authors: Tetuko Kurniawan, 陳炳萊
• Other Authors: An-Bang Wang
• Format: Others
• Language: en_US
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/31624738934494510419

碩士 === 國立臺灣大學 === 應用力學研究所 === 99 === An investigation on phenomena occurs when a drop impact onto deep liquid was done and two major cases were concentrated. In very small impact velocity of drop, partial coalescence phenomenon was investigated inside a controllable vacuum chamber. It was found that the reduced air pressure causes the period of coalescence cascade become shorter. It revealed that the reduced air pressure decreases the ability of drop to float and to pinch-off a secondary droplet. Another investigated case was the vortex ring produced by impacted drop. Extensive study on how to produce highly repeatable vortex ring was first conducted. It was found the hydrostatic and control of the drop nozzle is critical in producing repeatable drop-formed vortex ring. More details of experiment set up for such a system are discussed in this report such as how to reduce the meniscus and how to reduce current in the target liquid. As repeatable results have been achieved, series of experiment with various drop sizes and different liquids were conducted. It has been found that the maximum penetration depth Lmax occurs when impact drop shape near the peak of b1/R. The value of b1/R corresponds to the production of Lmax is around 0.9 peak value of b1/R. This finding was found valid for various drop sizes and various liquid conducted.