| Summary: | 博士 === 國立中央大學 === 機械工程研究所 === 98 === This thesis investigates the outcomes of drop impacting onto the moving dry surface. In the early stage of impacting, the bottom of the liquid drop adheres to the surface and is dragged by the moving surface simultaneously. The remainder of the drop governed by the force of inertia will remain and expand above the impacting point. Water drops with the characteristics of high surface tension and a smooth surface of rotating wafer are adopted in the experiment. Two major different outcomes are significantly appeared between the stationary and moving surfaces after impacting. Firstly, the deposited film is elongated by a moving surface to form an asymmetrical geometry, and the area of deposited film enlarges when the surface velocity increases. Secondly, either detachment or splashing which is impossible to be occurred in a smooth and stationary surface appears in high surface velocity. When the surface velocity or impingement angle reaches critical value, the upper portion of the droplet can be overcome the surface tension to result in droplet floating on the air, and then the detachment or splashing is formed. The faster surface velocity can reach the larger amount of detaching liquid is obtained.
The ethanol drops have the advantage of low surface tension. The impact outcome of an ethanol drop on a moving inclined surface is also investigated in the experiment. The outcome transformations can be observed by varying the surface inclined angles and the moving velocities. The gravity not only can promote the instability of the expanding film at downward flow also can stabilize the film at upward flow during the drop impact onto a stationary inclined surface. Considering the horizontal moving surface, the surface velocity excites the occurrence of splashing that is toward the opposite direction of surface movement, whereas it suppresses the splashing in the same direction of surface movement. When the inclined surface moves downward at a proper surface velocity, the impact outcomes can be changed from downward splashing to deposition. In other words, the regime of deposition is enlarged by an appropriate surface velocity, and this tendency is more obvious with a larger inclined angle.
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