<p>Many industrial processes, such as oil and gas transport, involve complex multiphase separation of liquids and gases. Design of effective phase separator is therefore crucial and first separators were utilized to break up the liquid-gas mixture in large tanks using gravity and density difference. Due to economic reasons, separation processes require smaller and more efficient equipment. Hydro-cyclones represent the valuable alternative to separate gas from liquid using a combination of centrifugal and gravity forces. When the centrifugal force is larger than the gravity, the liquid phase is pushed near the wall of the pipe while gas phase is concentrated at the center of the swirl. Nowadays in-line separators provide even smaller and more efficient alternative, where a centrifugal force produces a swirl flow and the bluff body, acting as a barrier, stabilize the two-phase flow. Previous studies focus on the performance of these two-phase flow separators, however the physical mechanism of swirl flow interacting with bluff bodies is still missing in the literature review. Studying this interaction can help engineers to improve the design of in-line separators in term of efficiency.</p><p>This study uses experimental approach to investigate the interaction between swirling flows and bluff bodies, using state-of-the-art flow visualization technique. The experimental set-up consists of a horizontal and transparent flow loop having both water and air injection system and a high-speed camera to visualize and record two-phase flow phenomena. The length of the test section is 1.22 m, with the inner pipe diameter equal to 41 mm. A circular obstacle is placed horizontally inside the test section and the high-speed camera records the interaction of bluff body with the swirl flow. To quantitatively characterize the observed two-phase swirl flow, an image-processing program, using MATLAB software, is developed. It is observed that the behavior of core region, the dynamic of air-water interface and the characteristics of turbulent region near the circular obstacle depend on both liquid and gas flowrates. A flow pattern map of swirl flow interacting with a circular obstacle is established. Several flow regimes are identified and, in particular, the results show the presence of a spiral axial flow for low values of gas–liquid ratio (GLR). Characteristics of capillary waves, observed along the air-water interface, are investigated. Both amplitude and wavelength of surface waves are measured and the influence of gas–liquid ratio, on mentioned surface waves, is reported. Obtained experimental results provide useful information on the behavior of swirl flow with a bluff body and are in particular helpful in developing and validating numerical models.</p>

Experimental Characterization of Two-Phase Swirl Flow Interacting With a Circular Bluff Body

Paper Proceedings: https://asmedigitalcollection.asme.org/FEDSM/FEDSM2021/volume/85284

ASME 2021 Fluids Engineering Division Summer Meeting (FEDSM2021)

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