Design and hydrodynamic analysis of an automated polymer composite mattress deployment system for offshore oil and gas pipeline protection

The protection of offshore oil and gas pipelines has become increasingly important due to its application in maritime transportation. Currently there are few deployment devices for pipelines and their operation was complicated. Therefore, a novel automatic polymer composite mattress deployment system is designed in this study, and its hydrodynamic performance is analyzed based on computational fluid dynamics (CFD). Firstly, the conceptual design of the system is introduced. Then, modeling and simulation are carried out on the system, including its forward movement, lateral movement, and heave movement at various speeds. Significant surface pressure was brought to the system during forward and lateral movement by the open frame design, with the maximum pressure during lateral movement reaching 719.46 Pa. During the heave movement, the mattress blocks the water flow, causing negative pressure on the surface of the system. The huge flow separation generated significant drag, with a maximum value of 12620.3 N. However, the mattress avoids the impact of water flow on the system. The longitudinal length of the mattress means the Reynolds number is greater than the other movements. The proportion of pressure drag further increases, reaching a maximum of 98.7%. This research provides new perspectives and solutions for the protection technology of pipelines.