| Summary: | 碩士 === 國立臺灣大學 === 機械工程學研究所 === 103 === The viscous and nanoparticle effect on droplet-droplet collision behavior at ambient conditions were studied experimentally. Glycerol solutions and silica nanofluids were used as working liquid providing viscosities in the range from 0.93 to 15.94 mPa‧s. The droplet image and collision history were recorded on a video recorder by using a strobe light synchronized with the droplet generator with various phase differences.
The collision outcomes in terms of Weber number and the impact parameter could be categorized into six distinct regimes: (I) coalescence after minor deformation, (II) bouncing, (III) coalescence after substantial deformation, (IV) reflexive separation, (V) stretching separation and, (VI) rotational separation. It is shown that, by varying the viscosity of the glycerol solution through its concentration, the border between bouncing and coalescence were shifted toward lower impact parameter until bouncing appears on head-on with increasing viscosity and verified empirical correlation for the onset of reflexive separation for high viscosity fluids. Furthermore, it was found the collision behavior of 1% weight percentage concentration nanofluids was the same with water and separation occurred at higher Webber number with increasing concentration.
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