为了掌握水平弯管内水合物浆的流动特性,采用基于颗粒动力学理论的欧拉双流体模型进行建模研究,其中RNG k-ε 模型用于模拟湍流运动,液固两相间的曳力体现相间耦合作用。结果表明,弯头处出现了明显的二次流现象,且速度最大值分布在偏向内侧横截面上;颗粒增大了管内水合物浆湍动能,并使弯曲段的浆液湍动能分布更均匀,弯管和水合物的存在对压能损失产生影响。在相同的水合物体积分数下,浆液压力梯度随平均流速的增加而增大;在相同的流速下,浆液压力梯度随水合物体积分数的增加出现了缓慢增长区、过渡区和快速增长区。为了对堵塞风险进行有效预警,除了考虑平均流速等因素,还需要从水合物生长过程中微观特性变化的角度对压降分区和流变多样性进行探索。
In order to study the flow characteristics of hydrate slurry, two-fluid Euler models based on the kinetic theory of the granular flow are established, in which the RNG k-ε model is used to simulate the turbulence movement and the drag force is used to express the interaction between the liquid phase and the solid phase. It is shown that secondary flows can clearly seen to arise in the elbow, and the maximum velocity occurs close to the inner side of the cross section; the hydrate slurry's turbulence kinetic energy in the 90° elbow is enhanced and the kinetic energy distribution is homogenized because of the hydrate particles; the presence of the elbow pipe and hydrates has a remarkable effect on the pressure energy losses. It is also shown that the pressure gradient of the hydrate slurry increases with its average velocity rising at the same hydrate's volume fraction, and that the pressure gradient of the hydrate slurry sees a slowly-growing zone, a transient zone and a rapidly-growing zone in turns with hydrate's volume fraction rising at the same velocity. The pressure gradient zoning and rheology diversity as well as the hydrate volume fraction have to be investigated from the point of microcosmic characteristics changes in hydrate's growth to early predict the pipeline plug risk.
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