Curved liquid jets: effect of scale, rheology and forced disturbances

Hawkins, Victoria (2011). Curved liquid jets: effect of scale, rheology and forced disturbances. University of Birmingham. Ph.D.

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Abstract

The creation of drops from the growth of surface tension instabilities on the surface of liquid jets has been exploited in many industrial applications. Curved jets are relevant to prilling, which creates small spherical pellets from molten material. There is a need to optimise the process to produce pellets of uniform size.

The dynamics of the break-up of curved jets is examined, with experiments investigating the effect of scale, rheology and surface tension, with particular focus on pseudoplastic liquids, using laboratory and pilot-scale facilities. The experiments were compared to previous work on Newtonian fluids, and existing numerical simulations, which use the method of finite differences to solve non-linear evolution equations for jet radius and axial velocity.

The effect of non-Newtonian rheology on the trajectory of the jet and linear instability are determined using computational and asymptotic methods. The droplet sizes produced by this instability are determined by considering the most unstable wave mode. This enables quantitative comparison with the experiments.

The influence of multiple disturbance frequencies (imparted by mechanical vibrations) on the break-up of curved Newtonian jets is investigated. Experimental data was compared with existing numerical models, to see if it is possible to predict where satellite droplets are eradicated.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

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