UBC Theses and Dissertations
Liquid jet interaction with a moving surface Kumar, Purushotam
An experimental study was conducted to study the splash-deposition characteristics of a liquid jet impinging on a moving surface. The main focus of this study was to determine the effects of fluid, flow and surface properties on the outcome of the jet impingement. Several parameters such as fluid viscosity, elasticity and surface tension, jet and surface velocity, jet diameter surface wettability and surface roughness were changed and their effects on splash-deposition characteristics were analyzed during this research work. For non-Newtonian fluids increase in the yield stress and consistency constant of the fluids helps in inhibition of the splash. At high Weber number the effects of surface tension and jet impingement angle were negligible compared to effects of Reynolds and Oldroyd numbers. But at smaller Weber number effects of surface tension were comparable to that of Reynolds number. It was also observed that the both normal (jet velocity) and tangential (surface speed) speeds play roles in splash-deposition dynamics. Newtonian liquid jet with smaller diameter illustrated that effect of surface tension becomes prominent only for liquids with low viscosities and for these liquids and 200 micron nozzle jets deposit up to 40 m/s. For high viscosity liquid same trend of deposition was observed and jets deposit up to 35 m/s. It was also observed that the jets of smaller viscosities spread on the surface very easily, making few micron sized lamella. Although higher viscosities liquid jets still spread very easily on the surface, the lamella thickness was much larger than that of low viscosity liquids. It was also found that mid-range viscosities jet started to splash at much lower velocities (13 m/s). This behavior is related to balancing of inertia forces by both the surface tension and viscous forces.
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