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ENCIT 2022
19th Brazilian Congress of Thermal Sciences and Engineering
Experimental investigation of bubble turbulent fragmentation in a centrifugal pump
Submission Author:
Luiz Carneiro , RJ , Brazil
Co-Authors:
Geniffer Stefany de Oliveira Martins, Cristian Mauricio Potosi Rosero, Luiz Carneiro, Juliana Loureiro, Atila Pantaleão Silva Freire
Presenter: Geniffer Stefany de Oliveira Martins
doi://10.26678/ABCM.ENCIT2022.CIT22-0538
Abstract
The present work studies the dynamics of bubble coalescence and breakup in centrifugal pumps. This is a problem of special interest for the design of phase separators. The performance of centrifugal pumps under the action of gas-liquid mixtures has been vastly discussed in the literature. Those papers are prodigal in assessing the impact of the gas fraction on several pump characteristics. One aspect that is not often dressed is the impact of these equipment on bubble fragmentation. The high levels of turbulent kinetic energy in a centrifugal pump have a direct influence in the stability and uniformity of the flow field, promoting changes in the flow patterns that may be difficult to predict. Bubble breakup may contribute to unexpected changes in phase configurations and diameter distributions and can have serious effects on the performance of phase separators. The experimental facilities consist of a volumetric pump acting as a booster, a compressor, a commercially available centrifugal pump to be studied, a intermediate separator reservoir, two flow observation apparatus. Flow rate sensors for the liquid and gas phases were used in conjunction with temperature and pressure sensors for the appropriate measurement of fluids properties. The flow loop was constructed in transparent piping allowing for the employment of Shadow Sizing technique to measure the disperse phase under high speed stroboscopic image acquisition. Care was taken to allow a flow development length on the inlet of the studied pump and the positioning of pressure sensors along the bench to allow the correction of gas volumetric flow rate. The work, in particular, discusses the use of a simple phenomenological theory based on dimensional analysis for the development of a simple expression capable of expressing the mean output diameter of bubbles in terms of the turbulent dissipation rate, the rotation and the diameter of the impeller. The arguments are similar to those of the early literature and are validated through experimental data obtained through the Shadow Sizing technique. The flow conditions consider the four expected flow patterns inside a two-phase gas-liquid pump. The volumetric gas-fraction is varied up to 12%
Keywords
centrifugal pump, multiphase flow, Turbulent kinetic energy, Artificial lift, gas bubbles
