Dynamic Characteristics Analysis And Scaling Experiment Study Of Deep-sea Flexible Pipeline Laying System

As the demand for oil from the ocean continues to grow,the need for subsea pipelines is growing.How to efficiently lay a large number of submarine pipelines in the future has become the key problem to be dealt with urgently.At present,the laying efficiency and laying depth of flexible pipeline laying system are the best.As a big importer of global oil,it is necessary to make a deep study on the efficient exploitation mode of offshore oil.Based on the technical requirements of flexible pipeline laying system,this paper introduces the overall scheme of laying system.On this basis,the shape and tension of flexible pipeline are analyzed by natural catenary method.The ship carrying the laying system was selected as a pipe-laying ship of CNOOC,and the environmental load of current,wave and sea breeze suffered by the ship during pipe-laying under the fourth-level sea conditions in the South China Sea was analyzed.The hydrodynamic characteristics of the pipe-laying ship,including the additional mass of the ship,the damping coefficient and the frequency amplitude function of the ship's motion response at six degrees of freedom,are analyzed by the submodule AQWA in ANSYS.In this paper,OrcaFlex was used to analyze the dynamic characteristics of flexible pipe laying,and the shape,tension,bending moment,stress and movement of the pipe laying ship were obtained through simulation under four-level sea conditions.The influences of wave height and wave period,wave direction Angle and laying Angle,laying water depth and laying Angle,as well as different pipe parameters on the maximum effective tension at the top of pipe and the maximum equivalent stress at the bottom point are analyzed.In this paper,the scaling model of the laying system tower is designed,and the similarity between the tower prototype and the scaling model is verified by ADAMS and ANSYS from the dynamic characteristics of the scaling model and the structural strength based on finite element numerical simulation.The analysis results show that the scaling model and prototype meet the given similarity rules under the derived scaling rules.Finally,the model experiment of the tower in the dangerous area of pipeline laying is carried out through the model experiment of structure mixing.The change rule of the stress in the dangerous area of the tower with the sea state is analyzed experimentally,which verifies the safety of the laid tower.