Dispersion of gas bubbles in turbulent oil flow

UDK: 621.691.4
DOI: 10.24887/0028-2448-2017-9-128-130
Key words: oil, turbulent flow, dispersity of gas bubbles, fluctuations in moles of liquid, maximum diameter of confined bubbles, maximum bubble diameter due to crushing conditions
Authors: Yu.V. Lisin, A.A. Korshak (The Pipeline Transport Institute LLC, RF, Moscow)

The gas bubbles in the turbulent flow of the liquid are polydisperse. Their diameter, as a rule, obeys the law of the normal logarithmic distribution, which is completely determined if the maximum particle size of the dispersed phase is known. Its value, in turn, depends on the ratio of the sizes of the bubbles held by the flow due to the vibrations of the moles of the liquid and the bubbles that can exist in the flow without breaking down. The article shows that the question of these characteristic diameters of gas bubbles has not been adequately studied at present. In deriving the calculation formula for the maximum diameter of a gas bubble, which the turbulent flow can hold, the authors have taken into account that the ascent of each individual gas inclusion in the gas-liquid flow slows down as a result of interaction with neighboring bubbles. To this end, the dynamic viscosity of the dispersion medium was replaced by the effective viscosity of the gas emulsion. In addition, from the empirical formula describing the weighted flows, a correction factor was taken, taking into account the occurrence of an additional restraining force when the moles of liquid fluctuate. Considering the crushing of suspended bubbles by turbulent pulsations, the authors have shown that the existing design formulas for particles in a dispersed phase (droplets, gas bubbles) are often distinguished only by the magnitude of the proportionality coefficient. A more reliable value of this coefficient was obtained by processing experimental data on the diameter of gas bubbles in tubing using gas lift. At the same time, the coefficient of hydraulic resistance was used as a measure of the energy dissipation in the pipes. Approbation of the calculated dependencies was performed by comparing the simulation results with the diagrams of the conditions for the existence of the oil-gas flow emulsion structure in horizontal pipes constructed by professor A.I. Guzhov and his students on the basis of visual observations in the conditions of oil industry. It is shown that, in general, the proposed formulas describe the experimental points with satisfactory accuracy. The existing discrepancies may be associated with inaccurate information about the properties of phases, as well as the subjectivity of the perception of flow structures by the observer.

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