Vibration Effects on Bubbly Flow Structure in an Annulus

Abstract

In order to investigate the seismic vibration effect on two-phase flow structure, experiments were performed for upwards bubbly flow in an annulus channel with and without externally-induced vibration. The inner and outer diameters of the annulus are 19.1 mm and 38.1 mm respectively, and the total height of the test section is 2.32 m. To simulate seismic vibrations, the test section is attached to an eccentric cam vibration module with an eccentricity of 9.5 mm. The eccentric cam rotation speed can reach up to 210 rpm. Local two-phase flow parameters were measured along radial direction within the annulus gap using miniaturized four-sensor conductivity probe at axial location of z/Dh = 77. The semi-instantaneous local parameters at different vibration angles were analyzed by tracing the quasi-sinusoidal acceleration signal under vibration conditions. The results showed that the seismic vibration can significantly affect the local parameters in bubbly flow regime. Void fraction can increase by 10% compared with non-vibration condition. During the vibration cycle, the void fraction also changed greatly, especially in the near wall region. The interfacial area concentration (IAC) and Sauter mean diameter displayed the same behavior as the respective void fraction profiles.