The work presented in this thesis consists of two parts. The first part deals mainly with the problems associated with flow patterns, pressure drops, settling lengths, void fractions, and their prediction. The second part describes methods evolved to define flow patterns from the characteristics of the pressure and void fraction fluctuations. A test rig was designed and constructed from transparent tubing with the main test section horizontal. The working fluids were air and water, at pressures and temperatures close to atmospheric, and the test conditions covered a range of air and water superficial velocities respectively of 0--> 28 m/s and 0 --> 5.1 m/s in a 127 mm nominal bore tube. 0 --> P-8.6 m/s and 0 --> 1.7 mf s in a 216 mm nominal bore tube. The experimental observations indicated asymmetric flows in general with a stratification effect superimposed on the normal flow patterns. Comparison with existing flow pattern maps showed an effect of tube diameter. The inadequacies of flow pattern maps are discussed. The experimental data relating to pressure drops and void fractions showed a strong flow pattern dependency, and correlations are presented for three main groups of flow patterns. These groups are (i) Annular Flows - incorporating annular, annular mist, rough wavy, etc. (ii) Intermittent Flows - incorporating bubble, plug and slug, (iii) Separated Flows - incorporating stratified and smooth wavy. Transition equations, defining the changes from one flow pattern group to another, were developed to enable predictions of flow. patterns for particular sets of conditions to be made. These were essentially based on a wave stability criterion. Comparisons were made between the experimental friction pressure drop and void fraction data and several well known correlations available in the literature. These showed poor agreement, in general. Pressure and void fraction probes were developed and tested with the object of obtaining more objective flow pattern measurements. These were used in conjunction with a high speed data acquisition system with a view to relating the statistical behaviour of the pressure and void fraction fluctuations to flow patterns. The results confirm the usefulness of these probes for this purpose.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:447656 |
| Date | January 1977 |
| Creators | Al-Samarra'e, F. A. A. |
| Publisher | University of Strathclyde |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=23500 |
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