内外流激励下深海水合物双层管柱非线性振动特性试验OA

An experimental simulation platform for the vibration of double-layer mining riser in deep-sea hydrate wells under internal and external flow excitation was developed in this study based on the principle of similarity to effectively explore its vibration mechanism.The influences of solid particle size,phase ratio,three-phase flow velocity,and external flow velocity on the vibration response characteristics and nonlinear behavior of internal continuous tubing were investigated.It is found that,the strong vibration positions of the vertical and horizontal sections of the mining string are different.In the vertical sec-tion,it is mostly located below the middle section(e.g.1 880 mm from the bottom),while in the horizontal section,it is mostly located 500 mm from the bend position.The vertical section of the mining riser can exhibit a motion trajectory of ob-lique straight line,wide oblique straight line,or approximately wide oblique straight line,while the horizontal section is mostly of a chaotic trajectory or an"8"-shaped chaotic trajectory.The decrease in particle mesh size and the increase in solid phase proportion can be reflected in the difficulty and accumulation of particle transport,leading to a decrease in vibra-tion displacement amplitude and vibration energy(such as the root mean square displacement reduced from 280 mm to 120 mm).The increase of the proportion of gas phase can lead to changes in the flow state of multiphase flow inside the pipe,re-sulting in more obvious internal multiphase flow disturbances.The vibration displacement of the mining riser shows an in-creasing trend.The increase in three-phase flow velocity can further induce vibration of the mining string,and there is a cer-tain flow velocity that will resonate with the string system(such as 1.75 m/s for vertical section and 2.00 m/s for horizontal section),resulting in a sudden increase in the amplitude of vibration displacement.