Some Mixing Flows of Industrial Relevance
In this thesis, theoretical and experimental investigation is undertaken into the steady mixing flows generated by rotating cylindrical and disc stirrers in Newtonian and non-Newtonian fluids. No mixing study is carried out. In Chapter 1, we briefly discuss the importance of the low speed mixing of fluids together with the processes involved and the different types of agitators and fluids found in common industrial applications. The literature reviewed in Chapter 2 covers previous work in flow visualisation techniques, power consumption of stirrers, fluid particle velocities and theoretical studies of flows. The chapter ends with an outline of the advantages and disadvantages of the techniques used by other investigators and the reasons for developing new methods for the purpose of this research. In Chapter 3, a description is given of the experimental arrangement and the flow visualisation technique used for this study. The procedure adopted along with the choice of the particular rotors and fluids studied are outlined. Also described are the methods used for characterisation of the test fluids and the mode in which various parameters were calculated. The theoretical and numerical methods which are employed in this work to simulate the experimental flows are detailed in Chapter 4. Numerical results obtained from these methods are compared with those of other workers for similar arrangements in Chapter 5. Experimental and theoretical results obtained for primary fIows are presented and compared i n Chapter 6 w i th the corresponding results for secondary flows discussed in Chapter 7. Couple values, Power numbers and discharge efficiencies obtained numerically are given in Chapter 8, together with a comparison of the theoretical and experimental couple values for the geometries investigated. All diagrams showing the results for Chapters 5, 6, 7 and 8 are given at the end of each chapter, while others are shown in the text. Finally, Chapter 9 outlines the conclusions reached from the work carried out and presents suggestions for possible future improvements and developments of the computer and experimental methods. Listings of some of the computer programs used for experimental and theoretical work and a copy of a published paper containing results of our preliminary investigations are given in the appendices.
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