Research on mechanical behaviors of submarine pipeline inspection gauges in the elbow: FSI simulation and mathematic modeling

Pigs applied for submarine pipeline inspection and cleaning operations frequently suffer from blockage risk when passing through the elbow. It is meaningful to understand the frictional contact characteristics of the pig when it runs through the elbow, which helps improve the traveling ability of the pig. In this paper, a basic assumption that the trajectory of the mandrel geometric center coincides with the pipeline central axis is put forward according to the 3D Fluid-Structure Interaction (FSI) simulation results, and then a dynamic analytical model that predicts the driving force and describes the mechanical behaviors of cup pig in the straight pipeline and the elbow is respectively derived using a novel algorithm combined with the modified Burgers-Frenkel (MB-F) model. The established analytical model was calculated by means of MATLAB programming. Take a specific working condition as an example, and a quantitative assessment method was proposed. Based on the calculation results of the analytical model, the frictional contact characteristic of the pig in the elbow was studied, and the traveling performance and security of the pigging operation were further evaluated.