Article

Effect and mechanism of disaster reduction of pipelines with double-elliptic streamline contour against impact of submarine landslides

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Abstract

With the rapid development of marine energy extraction, the demand for submarine pipelines has been increasing in recent years. The stability of pipelines during their service period directly affects the safety of the oil and gas exploitation, the workers' life and the marine ecological environment. In view of the fact that submarine pipelines are vulnerable to the damage from landslides, a novel type of submarine pipeline with a double-elliptic contour is developed. Then, the effect and mechanism of disaster reduction of the pipeline under the impact of landslides are analyzed based on the computational fluid dynamics (CFD) method. The results show that the developed pipeline, no matter in a suspended or laid-on-seafloor status, can delay the separation of velocity boundary layer near the pipeline surface to reduce the influence of Karman Vortex Street. Thus, the drag force and lift force of pipelines imposed by submarine landslides are effectively reduced,with a maximum lessening percentage of 71.01% for drag force coefficients and 32.14% for lift force coefficients. Moreover, the equations for estimating the drag force and lift force coefficients of double-elliptic contour pipeline are recommended, which provides a new reference for the disaster fortification and mitigation engineering on submarine pipelines.

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