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Title: Phase distribution and flow characteristics of isothermal co-current two-phase flow in horizontal pipes
Author: Harkly, Shawky Assaad
Awarding Body: University of Glasgow
Current Institution: University of Glasgow
Date of Award: 1956
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A review of the work already done on Co-current gas-liquid two-phase flow in horizontal pipes indicated that many of the conclusions reached and empirical formulae presented were based more on visual observations than on actual experimental measurements. The present research was initiated in an attempt to get by experimentation a clearer picture of the fundamental characteristics of this complex type of flow. The special apparatus and technique developed for measuring velocity, density and phase distribution over the pipe cross-section and the pressure drop along the pipe are described and the procedure outlined. The results are presented mainly in graphical form. From the results it has been possible to follow the changing pattern from the stratified form to the fully dispersed annular flow, through a series of modes which have hitherto been ill-defined as annular flow. The distribution of water entrained in the air stream is given in the form of concentration curves, a form which has not previously been used in gas-liquid flow. According to the rates of flow covered these curves have two quite distinct forms, the first, for low and moderate flow rates is exponential, and the second, for high rates, is tending progressively towards a symmetrical form. Correlations between the experimental results and a semi-empirical form gives agreement within +/-25% which at this stage, considering the complexity of the problem, is considered satisfactory. Velocity measurement by Pitot tube method has been used conservatively and its limitations discussed. The graphs presented show a similarity between entrained liquid particles in a gas stream and suspended solid particles in a liquid stream. The correlation of results is given and discussed in the light of turbulence concepts. Explanation of experimental findings are given. A study of the different ways of correlating pressure drops is made and although it yields promising results, yet it also indicates that the application of the fundamentals of turbulent flow is over simplified and fails to give reasonable prediction of pressure drops. A treatment of pressure drop using Fanning formula and applying the mean density of the core proves to be adequate within the range of experiments and it is suggested that such method may be used successfully if the mean density of the dispersed gas stream is predicted according to the semi-empirical formula given. A correlation analogous to those proposed for gas-solid flow is presented and show satisfactory results within +/-10%.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available