TY - JOUR

T1 - Stratified-to-annular gas-liquid flow patterns transition in a horizontal pipe

AU - Cherdantsev, Andrey V.

AU - Zdornikov, Semyon A.

AU - Cherdantsev, Mikhail V.

AU - Isaenkov, Sergey V.

AU - Markovich, Dmitry M.

N1 - Funding Information: The work was supported by grant 075-15-2019-1888 from the Government of the Russian Federation. The equipment was provided by Russian Science Foundation (project 19-79-30075). The authors thank Dr. A.V. Bobylev for manufacturing several components of the flow facility. Publisher Copyright: © 2021 Elsevier Inc.

PY - 2022/4/1

Y1 - 2022/4/1

N2 - Air-water flow in a 20 mm horizontal pipe is studied using side-view visualization with a background image and Brightness-Based Laser-Induced Fluorescence technique. The investigation is focused on the transition from stratified to annular flow patterns. Stratified flow is organized at the pipe inlet, and the dynamics of liquid lifting up the pipe walls is investigated. During the transition to annular flow, the liquid film is spread over the pipe walls in a stable and gradual manner; the spreading begins before the disturbance waves are formed. Two transition regimes are identified. At large gas and low liquid flow rates, the film is spread up the pipe walls reaching a stable height unaffected by the passing waves. At low gas and large liquid flow rates, the liquid can be lifted by the large-scale waves, but it promptly drains downwards between the waves. Secondary flow in the gas phase is considered the main mechanism of liquid lifting and the only mechanism able to create a stable annular film. The processes of formation and development of disturbance waves are qualitatively the same as previously observed in vertical pipes. Namely, the disturbance waves are formed due to the coalescence of high-frequency initial waves appearing near the inlet; the disturbance waves undergo coalescence and grow in amplitude and speed. Quantitatively, the disturbance wave formation occurs at larger distances from the inlet compared to the vertical flow, and the acceleration rate is much lower. An estimation of circumferential shear stress due to secondary flow is made based on the roughness of the liquid film surface at the bottom of the pipe. An increase in this shear stress increases the height of the liquid film on the pipe walls.

AB - Air-water flow in a 20 mm horizontal pipe is studied using side-view visualization with a background image and Brightness-Based Laser-Induced Fluorescence technique. The investigation is focused on the transition from stratified to annular flow patterns. Stratified flow is organized at the pipe inlet, and the dynamics of liquid lifting up the pipe walls is investigated. During the transition to annular flow, the liquid film is spread over the pipe walls in a stable and gradual manner; the spreading begins before the disturbance waves are formed. Two transition regimes are identified. At large gas and low liquid flow rates, the film is spread up the pipe walls reaching a stable height unaffected by the passing waves. At low gas and large liquid flow rates, the liquid can be lifted by the large-scale waves, but it promptly drains downwards between the waves. Secondary flow in the gas phase is considered the main mechanism of liquid lifting and the only mechanism able to create a stable annular film. The processes of formation and development of disturbance waves are qualitatively the same as previously observed in vertical pipes. Namely, the disturbance waves are formed due to the coalescence of high-frequency initial waves appearing near the inlet; the disturbance waves undergo coalescence and grow in amplitude and speed. Quantitatively, the disturbance wave formation occurs at larger distances from the inlet compared to the vertical flow, and the acceleration rate is much lower. An estimation of circumferential shear stress due to secondary flow is made based on the roughness of the liquid film surface at the bottom of the pipe. An increase in this shear stress increases the height of the liquid film on the pipe walls.

KW - Annular flow

KW - Disturbance waves

KW - Flow development

KW - Flow pattern transition

KW - Laser-induced fluorescence

KW - Stratified flow

UR - http://www.scopus.com/inward/record.url?scp=85119586253&partnerID=8YFLogxK

U2 - 10.1016/j.expthermflusci.2021.110552

DO - 10.1016/j.expthermflusci.2021.110552

M3 - Article

AN - SCOPUS:85119586253

VL - 132

JO - Experimental Thermal and Fluid Science

JF - Experimental Thermal and Fluid Science

SN - 0894-1777

M1 - 110552

ER -