Flow visualization in centrifugal pumps: A review of methods and experimental studies

by Rodolfo Marcilli Perissinotto, William Monte Verde, Jorge Luiz Biazussi, Natan Augusto Vieira Bulgarelli, William Denner Pires Fonseca, Marcelo Souza de Castro, Erick de Moraes Franklin, Antonio Carlos Bannwart, published at Journal of Petroleum Science and Engineering Volume 203, August 2021, 108582


Methods for flow visualization have been decisive for the historical development of fluid mechanics. In recent years, technological advances in cameras, lasers, and other devices improved the accuracy and reliability of methods such as High-Speed Imaging (HSI) and Particle Image Velocimetry (PIV), which have become more efficient in visualizing complex transient flows. Thus, the study of centrifugal pumps now relies on experimental techniques that enable a quantitative characterization of single- and two-phase flows within impellers and diffusers. This is particularly important for oil production, which massively employs the so-called Electrical Submersible Pump (ESP), whose performance depends on the behavior of bubbles and drops inside its impellers. Visualization methods are frequently used to study gas-liquid flows in pumps; however, the visualization of liquid-liquid dispersions is complex and less common, with few publications available. Methods to characterize the motion of gas bubbles are often unsuitable for liquid drops, especially when these drops are arranged as emulsions. In this context, there is room to expand the use of visualization techniques to study liquid-liquid mixtures in pumps, in order to improve the comprehension of phenomena such as effective viscosity and phase inversion with focus on the proposition of mathematical models, for example. This is a main motivation for this paper, which presents a review of researches available in the literature on flow visualization in centrifugal pumps. A broad set of studies are reported to provide the reader with a complete summary of the main practices adopted and results achieved by scientists worldwide. The paper compares the methods, investigates their advantages and limitations, and suggests future studies that may complement the knowledge and fill the current gaps on the visualization of single-phase flows, gas-liquid, and liquid-liquid mixtures.

DOI: 10.1016/j.petrol.2021.108582

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Experimental analysis on the behavior of water drops dispersed in oil within a centrifugal pump impeller

by Rodolfo Marcilli Perissinotto, William Monte Verde, Carlos Eduardo Perles, Jorge Luiz Biazussi, Marcelo Souza de Castro, Antonio Carlos Bannwart, published at Experimental Thermal and Fluid Science, Volume 112, 1 April 2020, 109969.


This paper aims to investigate the behavior of water drops in an oil continuous medium inside a centrifugal pump impeller working at eight operational conditions (up to 1200 rpm and 2.8 m³/h) with two-phase liquid-liquid flows. Water-in-oil dispersions were produced with low water fractions around 1% in volume, thus the dispersed phase became arranged as water drops. Experiments for pump performance and flow visualization were conducted using a high-speed camera and a pump prototype with a transparent shell. Flow images revealed that the large water drops usually deform, elongate, and break up into smaller ones, especially at high pump rotations and oil flow rates, while small water drops tend to keep their spherical geometry without deformations and fragmentations. A sample of drops were tracked and their equivalent diameters, residence times, and velocities were calculated. The tracking indicated that the water drops travel random trajectories in the channels, generally undergoing a deceleration along their pathway. Furthermore, the residence times and the average velocities of water drops strongly depend on the flow conditions. For the conditions tested, the water drops presented equivalent diameters between 0.1 and 6.0 mm, average velocities from 0.4 to 1.7 m/s, and residence times between 30 and 152 ms. For a more complete analysis, the results achieved in this study are constantly compared with results available in literature regarding oil drops in oil-in-water dispersions.

DOI: 10.1016/j.expthermflusci.2019.109969

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