Investigation on mechanical behaviour of underwater launching process of bidirectional pigging robot in the subsea oil pipeline using Coupled Eulerian-Lagrangian method

Underwater launchers are typically employed for the deployment of pigging robots in subsea pipelines for the purposes of cleaning and inspection. Throughout the launching process, challenges related to vibration, damage, and other issues must be addressed and resolved. In this study, the launching process of the pigging robot is numerically simulated using Abaqus 2020. Utilising the Coupled Eulerian-Lagrangian (CEL) method, the Fluid-Structure-Interaction (FSI) model of the launching process was constructed. And the variation of parameters such as velocity, friction force and tilt angle at different inlet flow rates were analysed. The findings indicate a positive correlation between the average velocity of the pigging robot and the inlet flow rate. The factors such as friction, tilt angle, and offset distance are related to the motion process of the pigging robot. Furthermore, during the pigging robot’s traversal through narrow pipe sections, the sealing discs undergo irregular deformation, generating a reaction force on the robot and inducing vibration. In conclusion, the analysis of the impact of inlet flow velocity on the motion behaviour of the pigging robot offers a theoretical foundation and reference for the successful launch of the robot.