Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.638431
Title: Oscillations in jet agitated systems
Author: Paulussen, R.
Awarding Body: University College of Swansea
Current Institution: Swansea University
Date of Award: 1980
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Abstract:
This thesis is about standing waves on the surface of liquids. These waves have no purpose, but are the result of the action of a liquid or gas jet. Most of the work has been done on oscillations of one particular kind, i.e. asymmetrical and of mode one. An effort is made to predict amplitudes by equating energy input to energy dissipation. This leads only to a qualitative understanding of the nature of these oscillations. This is due to the fact that the energy dissipation in the waves is very small compared with viscous friction in the rest of the column. The jet plays an important role in inducing the waves. For that reason the characteristics of jet flow are investigated. 'his involves determining axial velocities and velocity profiles. The rest Its compare favourably with predictions made in the literature. Amplitudes of oscillations induced by an air jet are determined. This was done as a function of column height, diameter, density, viscosity and flowrate. It appears that it is the entrained liquid in the jet that causes the oscillations. They are therefore essentially the same waves as the ones induced by a liquid jet, plus quite often a jet is used for mixing. It was thought useful to determine how a deflector plate and a draught tube - both can be used to suppress oscillations - affect the mixing performance in a cylindrical vessel. This was achieved by changing the salinity of the jet in a stepwise fashion and measuring the response with a conductivity cell. It appears that the mixing is kept nearly ideal for a column equipped witha plate or a tube. Without these appliances - when waves are induced - the,ratio of residence times Treal/T ideal falls to 0.6.Finally a system of multiple jets was investigated. Various kinds of waves can be induced, depending on the liquid depth. The jets combine to a smaller snumber of jets to support the oscillations. Viscosity, density and flowrate have no effect on this. They do have an influence on the amplitudes.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.638431  DOI: Not available
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