Submerged gas jet in liquid cross flow: Modeling and flow structures analysis

The influence of the liquid cross flow is important to the flow structure of submerged natural gas jet release from underwater pipelines. In the present study, the development of a submerged gas jet subjected to liquid cross flow is experimentally and numerically investigated to evaluate the effects of the cross flow on the underwater gas jet evolution. Experimentally, a full-scale experimental setup is designed and developed for submerged gas jet release and dispersion in the liquid flow with different cross velocities. The interaction between the gas jet and liquid cross flow and the jet morphology are captured by shadow photography combined with a high speed video camera, and the images are processed to extract the jet parameters and perform Proper Orthogonal Decomposition (POD) analysis to reveal the characteristics of different modes which refer to different flow structures. Numerically, a computation fluid dynamics model tested and verified by the experimental results is used to analyze the submerged gas jet in more detail. A modified integral model considering the jet entrainment and the effects from the liquid cross flow is proposed to predict the jet evolution. It turns out that the modified integral model is able to predict the jet development accurately, including trajectory, jet inclination angles and penetration length, which will provide convincing assessment and opportunity to take prompt response to control potential accidents caused by the submerged natural gas jet release in liquid cross flow.