【摘 要】
：
In this study, the collision of three water drops aligned in the vertical direction was examined experimentally using a free-falling drop apparatus under three conditions, namely no flow (quiescent ai
【机 构】
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Department of Mechanical Engineering, National Cheng Kung University, Tainan, Taiwan
【出 处】
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13th International Conference on Liquid Atomization and Spra
论文部分内容阅读
In this study, the collision of three water drops aligned in the vertical direction was examined experimentally using a free-falling drop apparatus under three conditions, namely no flow (quiescent air, vg = 0 m/s), convective air flow (vg = 0.3 - 1 m/s), and hot flow (vg = 2.5 m/s). Three initial drop diameters (di ≈ 500, 700, and 900 μm) and three initial dimensionless drop spacings (Si ≈ 2.5, 5 and 10) were considered in the experiment. In the downward movement of three aligned drops with given values of di and Si, the first two drops first merge into a large drop, which then merges with the remaining drop. The results show that for all cases, the leading merged position increases linearly with the initial gas velocity because of a rear-ending process along the same axis, except for Si ≈10 with di ≈ 900 μm. For these values, the leading merged position increased exponentially with the initial gas velocity. Further, the final merged position increased exponentially with the initial gas velocity for Si ≈ 2.5 and 5 with di ≈ 500, 700, and 900 μm. The final merged occurred in hot flow for Si ≈ 2.5 with di ≈ 500 and 700 μm and for Si ≈ 5 with di ≈ 500 μm. It was found that the position of the merging drop collisions which resulted in merged shifted downstream with larger initial drop diameter, larger initial drop spacing, and higher initial gas velocity due to the weakened wake effect. The leading merged collision included along the same axis condition and under the off-center condition, but the final merged collision occurred only under the off-center condition. The oscillation period of the leading merged increased with increasing initial drop diameter, but the final merged did not exhibit a oscillate cycle.
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