【作者】 高琪；

【导师】 刘秋生；

【作者基本信息】 清华大学 ， 力学， 2005， 硕士

【摘要】 油水混合液的快速、高效分离是海洋油气开采和输送中亟待解决的技术问题。设计小型、快速、高效的复合式油水分离器是目前油水分离技术研究的一个方向。螺旋管油水分离器是一种体积小、效率高的分离设备,管内两相流动和分离过程的研究对于分离器的设计有重要意义。本文利用 FLUENT 软件,采用不可压湍流 Navier-Stokes 方程和两相流动的 Euler 模型,对螺旋管内油水两相流动和分离过程进行了数值研究。计算考虑了小孔出流的工况,得到了油水两相流动特性和分离特性,数值计算结果和实验数据吻合较好。结合实验数据进行了分离机理的分析,并对实验研究的油水分离螺旋管结构提出了改进建议。液液两相流动中,分层流动是一种常见的流态。石油工业中,油水分层混输是一种重要的输送技术。对于两相分层流动的研究往往通过对相间和壁面上剪应力的研究,从宏观上来把握两相流动的特性,从而确定体积流量、体积组分和沿程压降之间的关系。两相分层流动的界面通常为平的,但是在某些特定的情况下,由于表面张力的作用不能被忽略,使得相间界面呈曲线形状,例如,微重力下,毛细系统中,两相密度相差很小时。本文利用 FLUENT 软件中的 VOF方法,以及利用 Level-Set 方法编写程序对考虑表面张力和接触角的两相分层流动进行了数值研究,并比较了两种方法。同时,本文还修正并推导了考虑表面张力和接触角效应的界面形线解析解,并将解析解结果用于改进二流模型(Two-Fluid Model,TFM)。TFM 是针对两相分层流动提出的数学模型,用以描述两相分层流动的特性。本文利用界面形线解析解,并结合对摩阻系数、特征速度、水力半径的修正,将适用于气液两相分层流动的 TFM 推广到适用于考虑表面张力和接触角的液液两相分层流动。改进的二流模型和小管径油水分层流动的实验结果吻合的很好,不但能很好的预测三相点位置和流动压降,而且能捕捉两相流动特征速度的转捩区域。修正的二流模型对指导油水混输具有一定的应用价值。更多还原

【Abstract】 It is a strong desire to develop a high-efficiency oil-water separationtechnology for the offshore oil-gas exploitation and transportation. To designa compact, high-efficiency compound oil-water separator is a main goal of theresearch in this field. The helically coiled tube separator is one of theseefficient equipments. The investigation of the separation of oil-watertwo-phase flow in a helically coiled tube is important for the designing.Therefore, in this paper, the software, FLUENT, is applied for numericalsimulation, in which the Euler-Euler method and Euler model are adopted.The experimental condition with holes on the out side of the helical tube isconsidered in the simulation. The characteristics of the flow and themechanism of separation are studied and the numerical results agree well withthe experimental data. Some suggestions for improving experimental researchare made.Stratified flow is considered a basic flow in two-phase system. Themixed transferring of stratified flows is an important technology in petroleumengineering. Research in two-phase stratified flow, which aims to know thecharacteristics of the flow integrally and the relationship between the volumeflow ratio, the hold-up and the pressure drop, normally focuses on the shearstress between the wall and the phases or between the phases. Generally, theinterface between two phases is plane, except in some special conditions, suchas in reduced gravity systems, capillary systems, in the case of low densitydifferential or small ID pipe flows. In these cases, the surface forces becomeimportant compared with the gravity and thus the interface between twophases is curved. We did some numerical experiments by the VOF method inFLUENT and the Level-Set method. Both the advantage and the disadvantageof these two methods are given in the paper. A corrected exact analyticalsolution for the interface shape of two-phase stratified flow, which considersthe effects of the surface tension of the two fluids and the contact angle, isgiven. The analytical solution has been used to improve the Two-Fluid Model(TFM).TFM is a model for two-phase stratified flow. It can describe theattribute of the flow. We improve the old TFM by redefining the frictionfactors, characteristic velocities, hydraulic radius. The Advanced Two-FluidModel (ATFM) is developed to fit the liquid-liquid two-phase stratified flowwith the curved interface and the results fit well with the experiment results ofthe oil-water stratified flow in small ID tubes. The ATFM can not only predictthe position of three-phase point and the pressure drop, but also obtain thetransition range for the characteristic velocities of the two phases. It is ofpractical value for the oil-water mixed transferring.更多还原