| Summary: | 碩士 === 國立成功大學 === 機械工程學系 === 102 === The interaction of two drops in the direction of the stream is studied experimentally using a free-falling drop apparatus which provides different gaseous flows, cold flow (vg = 0 - 0.5 m/s) and a hot flow (vg = 2.5 m/s). Both water and dodecane were used in the experiments, and thus there are two main parts to discuss.
Two aligned water drops moved downward in the same direction of cold and hot flow. It was found that the travelling velocity of the trailing drop was higher than that of the leading drop due to the wake effect. The merging collision process was found to the same for three different flows. However, the position of the merging collision of the drops shifted downstream of the flow with a greater initial drop spacing and higher initial gas velocity, and this weakened the wake effect. It was found that the initial drop spacing was more dominated than the initial gas velocity in this experiment.
Two aligned dodecane drops moved downward only in hot flow. The two dodecane drops were affected by the interactions among the thermal expansion, convective effect caused by the different flame structures in the combustion chamber, and exhibited four main flame transition modes. It was found that the interaction of two drops was dominated by the initial drop spacing (Si), with the initial drop diameter (di) also having an effect. The different flame structure and Reynolds number would affect the vaporization rate (k) of a leading drop or a trailing drop.
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