淹没水射流关键参数对天然气水合物沉积物冲蚀体积的影响规律研究

Influence of key parameters of submerged water jets on the erosion volume of natural gas hydrate sediments

高压水射流技术具有工作介质来源广泛与环保等优点,能够用于海底天然气水合物储层破碎。本文运用LSDYNA有限元程序对淹没状态下高压水射流对海洋天然气水合物沉积物破碎过程进行数值模拟,研究了射流速度、喷嘴直径、靶距、入射角度4项关键参数对含水合物沉积物冲蚀体积的影响,得出以下主要结论:含水合物沉积物破碎需要满足射流速度大于临界流速;随着射流速度的增加冲蚀体积逐渐增大;喷嘴直径的增加会导致沉积物径向冲蚀体积的增大,从而使总体冲蚀体积增大;靶距的增加会使水射流在水域运动过程中能量损失增大,导致冲蚀体积的减小;在喷嘴入射角度增大过程中冲蚀体积先增大后减小最后趋于稳定,当入射角度为10°时冲蚀体积能够达到最大值。

The high-pressure water jet technology provides many advantages such as a wide range of working mediums, environmental-soundness, and can be used to break the submarine gas hydrate formations. In this paper, the LS-DYNA finite element program is used to simulate the fragmentation process of submarine gas hydrate formations with high-pressure water jets under the submerged condition. The effects of four key parameters(jet velocity, nozzle diameter, target distance and incident angle) on the erosion volume of hydrate formations are studied. The following conclusions are drawn: the requirement that jet velocity is higher than the critical velocity needs to be met for fragmentation of hydrate sediments;the erosion volume gradually increases with the increase of jet velocity;the increase of nozzle diameter will lead to the increase of the radial erosion volume of formations, hence the overall erosion volume;the increase of target distance will increase the energy loss of water jets in the process of water movement, leading to the decrease of the erosion volume;the erosion volume will increase first and then decrease with the increase of nozzle incidence angle, eventually becoming stable. When the incident angle is 10°, the erosion volume can reach the maximum value.