Merging collision of a drops stream

C. W. Lee, C. K. Chen, L. T. Huang, P. K. Hsu, T. H. Lin

Research output: Contribution to conferencePaperpeer-review


In this study, a collision of stream water drops aligned in a vertical direction was examined experimentally using a freefalling drop apparatus that provided two gaseous conditions, namely no flow (quiescent air, vg = 0 m/s) and convective air flow (vg = 0.3 and 0.5 m/s).The initial drop diameter (di) was kept at 900 μm. Drops generated for examination were considered to be two drops, three drops and a drop stream. Two initial dimensionless drop spacings, Si = 5 and 10, were selected in the experiment. The Reynolds number of drops depended on the drop velocity, drop diameter and vg in the free-falling drop process. The drop wake effect was affected by the initial drop spacing (Si), Reynolds number (Re), and number of drops in the free-falling drop process. The effect of Si was more dominant than that of the Re and the number of drops. In the downward movement process of drops with a given Si, the first merging of the first two drops was observed at first and then resulted in a large drop; thereafter this large drop was caught by the last drop showing the second merging. The first merged collision occurred either along the same axis or in an off-center situation, but the second merged collision occurred only in the off-center situation. The results showed that the merged drop position shifted to the downstream region with increases in vg or Si and that variations in the merged position shifted from linear to exponential with increases in the number of drops under the same di and vg conditions.

Original languageEnglish
Publication statusPublished - 2015
Event13th International Conference on Liquid Atomization and Spray Systems, ICLASS 2015 - Tainan, Taiwan
Duration: 2015 Aug 232015 Aug 27


Conference13th International Conference on Liquid Atomization and Spray Systems, ICLASS 2015

All Science Journal Classification (ASJC) codes

  • Surfaces, Coatings and Films


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