TY - JOUR

T1 - Axial and azimuthal development of disturbance waves in annular flow in a horizontal pipe

AU - Zdornikov, Semyon A.

AU - Isaenkov, Sergey V.

AU - Cherdantsev, Andrey V.

N1 - The work has been supported by Russian Science Foundation, project 19-79-30075. The equipment was provided by Ministry of Science and High Education of Russia (project 075-15-2022-1043).

PY - 2024/2

Y1 - 2024/2

N2 - Transformation of gas-liquid flow in a horizontal pipe is investigated during the transition from stratified to annular flow pattern. Using Brightness-Based Laser-Induced Fluorescence technique, spatiotemporal evolution of liquid film thickness is analyzed over the downstream distance range of about 900 mm (45 pipe diameters), starting from the inlet. The measurements are carried out for three values of azimuthal angle θ: 0 (pipe bottom), 90°, and 180°, to track the circumferential spreading of liquid film and disturbance waves. At large gas velocities, thin liquid film is dragged upwards before the formation of large waves. The disturbance waves are created at the pipe bottom and spread circumferentially as they propagate downstream, over the already-wetted pipe walls. At large enough liquid flow rates, the spreading disturbance waves reach the pipe ceiling and form full rings around the circumference. The frequency and velocity of the disturbance waves eventually become the same around the pipe circumference; the disturbance wave amplitude and the base film thickness decrease with θ. The base film is more uniform around the circumference compared to the wave amplitude. At lower liquid flow rates, the disturbance waves cover only a part of pipe circumference. Their edges demonstrate oscillatory circumferential spreading, which ends by deceleration and decay of the edges. The upper part of the pipe may be wetted by a thin base film layer, covered only with ripples, or remain dry. At low gas speeds and large liquid flow rates, occasional splashing of large waves over the pipe ceiling without pre-wetting by the thin film is possible; however, the remaining film drains downward and no stable annular film is maintained. Liquid droplets, entrained from the pipe bottom and depositing in the upper parts of the pipe, are gathered in trains of creeping pendant droplets at the very top part of the pipe; no continuous wetting is achieved due to droplet deposition.

AB - Transformation of gas-liquid flow in a horizontal pipe is investigated during the transition from stratified to annular flow pattern. Using Brightness-Based Laser-Induced Fluorescence technique, spatiotemporal evolution of liquid film thickness is analyzed over the downstream distance range of about 900 mm (45 pipe diameters), starting from the inlet. The measurements are carried out for three values of azimuthal angle θ: 0 (pipe bottom), 90°, and 180°, to track the circumferential spreading of liquid film and disturbance waves. At large gas velocities, thin liquid film is dragged upwards before the formation of large waves. The disturbance waves are created at the pipe bottom and spread circumferentially as they propagate downstream, over the already-wetted pipe walls. At large enough liquid flow rates, the spreading disturbance waves reach the pipe ceiling and form full rings around the circumference. The frequency and velocity of the disturbance waves eventually become the same around the pipe circumference; the disturbance wave amplitude and the base film thickness decrease with θ. The base film is more uniform around the circumference compared to the wave amplitude. At lower liquid flow rates, the disturbance waves cover only a part of pipe circumference. Their edges demonstrate oscillatory circumferential spreading, which ends by deceleration and decay of the edges. The upper part of the pipe may be wetted by a thin base film layer, covered only with ripples, or remain dry. At low gas speeds and large liquid flow rates, occasional splashing of large waves over the pipe ceiling without pre-wetting by the thin film is possible; however, the remaining film drains downward and no stable annular film is maintained. Liquid droplets, entrained from the pipe bottom and depositing in the upper parts of the pipe, are gathered in trains of creeping pendant droplets at the very top part of the pipe; no continuous wetting is achieved due to droplet deposition.

KW - Annular flow

KW - Disturbance waves

KW - Flow asymmetry

KW - Flow development

KW - Horizontal pipe

KW - Laser-induced fluorescence

UR - https://www.scopus.com/record/display.uri?eid=2-s2.0-85181072502&origin=inward&txGid=0d0fa61a3785d776381d3f32d4b12628

UR - https://www.webofscience.com/wos/woscc/full-record/WOS:001149809800001

UR - https://www.mendeley.com/catalogue/7735056f-510b-3000-a764-31e50a5c3b61/

U2 - 10.1016/j.ijmultiphaseflow.2023.104704

DO - 10.1016/j.ijmultiphaseflow.2023.104704

M3 - Article

VL - 172

JO - International Journal of Multiphase Flow

JF - International Journal of Multiphase Flow

SN - 0301-9322

M1 - 104704

ER -