Author(s): Leila Dhar; Gregoire Recchia; Florentin Anne; Cedric Beguin; Stephane Etienne; Laurent Bornard; Philippe Cote
Linked Author(s): Michel Sabourin
Keywords: Two-phase flow; Air injection; Gas jet; Liquid cross flow; Bubble trajectory
Abstract: Bubble plumes in crossflow are commonly encountered in various practical applications such as artificial aeration in rivers and in hydroelectric facilities. The injection of air through turbine runners can increase dissolved oxygen levels in downstream rivers and optimize turbine efficiency. However, despite its importance, the interaction between gas jets and liquid crossflows is not well understood due to the challenges involved in experimental research. To address this issue, a new experimental method was developed in this study, which utilized a high-speed camera to capture the evolution of the gas sheet injected through rectangular slots in liquid crossflow up to 4 m/s. The study provides a thorough description of the air layer morphology and its evolution in the test section, highlighting two main regions: the parabolic trajectory near the injection and the linear trajectory after detachment from the lower wall. The effects of the momentum flux ratio, cross-flow velocity, and buoyancy on the penetration height and detachment length of the gas cavity are explained. Moreover, our work emphasize the influence of slot geometry on the gas layer trajectory. Finally, correlations were developed to predict the centerline trajectory and characteristics of the submerged gas layer in cross-flow.