Abstract:

The motion and deformation characteristics of discrete oil droplets in a pipe with variable cross-section was one of the core problems in revealing the mechanism of two-phase flow. The discrete oil droplets inside the sudden contraction and sudden expansion round pipe were taken as the research object, and numerical simulation and high-speed camera experiment were combined to study the motion and deformation characteristics of oil droplets inside the sudden contraction and sudden expansion round pipe under different inlet Reynolds numbers. The results showed that in the sudden contraction and sudden expansion round pipe, at conditions of the same Reynolds number, as the particle size of the discrete oil droplet increased, the pressure at the inlet end of the pipe and in the sudden construction zone increased, the pressure rose faster in the area of sudden expansion, and the largest deformation of oil droplets was in the thin pipe section. Simultaneously, when the particle size of oil droplets unchanged, the deformation of discrete oil droplets in the pipe increased with the increase of inlet Reynolds number, and the initial broken position of the oil droplets in the pipe was closer to the shoulder of the protruding axis and the degree of brokenness was more intense. What's more, when Re=6.3×10³, the deformation of oil droplets reached the maximum value of 0.84 and the initial crushing position was 33.2mm away from the shoulders of sudden expansion. In addition, the motion, deformation and fragmentation laws of discrete oil droplets in the sudden contraction and sudden expansion round pipe under different inlet Reynolds numbers and oil droplet sizes were obtained. Thus, this paper provided theoretical reference for strengthening oil-water two-phase flow mixed transport in surface crude oil gathering and transportation network.

Key words: numerical simulation, oil droplet, two-phase flow, flow, motor behavior, deformation properties

摘要：

离散油滴在变截面管道内的运动及变形特性是揭示两相流动机理的核心问题之一。以突缩突扩圆管内的离散油滴为研究对象，采用数值模拟与高速摄像实验相结合的方法，针对不同入口雷诺数条件下突缩突扩圆管内的油滴运动行为及变形特性开展研究。结果表明：在突缩突扩圆管内，当入口雷诺数相同时，随着离散油滴粒径的增大，管内入口端及突缩区压力增大，突扩区压力回升加快，且油滴最大变形量在细管段。当油滴粒径不变时，随着入口雷诺数的增大，管内离散油滴变形量越大，油滴在管道内初始破碎位置越靠近突扩双肩且破碎程度越剧烈。当Re=6.3×10³时，油滴的变形量达到最大值0.84，初始破碎位置在距离突扩双肩33.2mm处。得到了不同入口雷诺数及油滴粒径条件下突缩突扩圆管内离散油滴的运动、变形及破碎规律，为地面原油集输管网中油水两相流混输强化提供了理论参考。

关键词: 数值模拟, 油滴, 两相流, 流动, 运动行为, 变形特性