气液两相环状流中夹带液滴特性研究 下载本文

(2)液滴直径和气相速度成反比,而对于液相表观速度,一些情况下使液滴直径增大,另一些情况下使液滴直径减小。但对于水平流动和垂直流动,液滴直径正比于液相表观速度,因为气相和液相之间的相对速度决定了液滴直径,液滴直径随着相对速度的减小而增大,即较大的液相速度能产生较大的液滴。同时液滴直径随着管径的增大有增大的趋势。

(3)液滴速度分布的研究表明液滴速度为气相速度的80%时,液滴平均速度随着气相速度的增大而增大。实验观察到液滴速度随着气相和液相速度的增大有很小的上升趋势,直到液滴速度达到气相速度的80%。同时液滴速度分布的散布随着气相速度的增大而增大,气相速度越大,产生的液滴越小,而这些较小的液滴以更大范围的速度运动,这是因为较小的液滴容易受气相湍流的强烈影响,引起横向加速和减速,使液滴速度发生变化,而较大的液滴,不易受湍流的影响,表现出较窄的速度范围。

(4)夹带过程是由高速气相引起的,高速气相会剪切由于液相和气相之间的速度差而在气液界面上产生扰动波的波峰。夹带分数是用于估计液相以液滴形式进入气流时的数量。研究表明夹带分数随着液相和气相流率的增大而增大,但是主要受气相表观速度的影响。

参考文献:

[1] David F. Tatterson,John C. Dallman,Thomas J. Hanratty. Drop sizes in annular gas-liquid flows[J]. American

Institute Of Chemical Engineers,1977,23(1):68-76.

[2] L.E. Patrunoa,P.A. Marchioro Ystadb,C.B. Jenssenc,et al. Liquid entrainment-droplet size distribution for a

low surface tension mixture[J]. Chemical Engineering Science,2010,,65(18):5272-5284.

[3] Fore. L.B,Ibrahim. B.B,Beus. S.G. Visual measurements of droplets size in gas-liquid annular flow[J].

International Journal of Multiphase Flow,2002,28(12):1895-1910.

[4] Kocamustafaogullari. G,Smits. S.R.,Razi. J. Maximum and mean droplet sizes in annular two-phase flow[J].

International Journal of Heat and Mass Transfer,1994,37(6):955-965.

[5] Azzopardi. B.J. Drops in annular two-phase flow[J]. Experiments in Fluids 1985,3(1):53-59. [6] Fore. L.B,Dukler. A.E. The distribution of drop size and velocity in gas-liquid annular flow[J].. International Journal of Multiphase Flow,1995,21(2):137-149.

[7] Pan Lei,Hanratty. Thomas J. Correlation of entrainment for annular flow in horizontal pipes[J]. International

Journal of Multiphase Flow,2002,28(3):385-408.

[8] 雷雨.湿天然气管道低含液率气液两相流液滴夹带机理研究[D]. 西安:西安石油大学,2015.

[9] Pravin Sawanta,Mamoru Ishiia,Michitsugu Morib. Droplet entrainment correlation in vertical upward

co-current annular two-phase flow[J]. Nuclear Engineering and Desig,2008,238(6):1342-1352.

[10] M. A. Lopez de Bertodano,A. Assad,S. G. Beus. Experiments for entrainment rate of droplets in the annular

regime[J]. International Journal of Multiphase Flow,2001,27(4):685-699.

收稿日期:2015-11-24

作者简介:樊文娟,女,西安石油大学石油工程学院在读硕士研究生,研究方向为油气储运工程专业。

The characteristics of the entrained droplets in the gas-liquid two-phase annular flow

Abstract:The liquid film flows along the pipe wall and the larger speed gas nucleusflows in the center of the pipe flow in the gas-liquid two-phase annular flow,

usually the high speed gas nucleus entrained part of droplets. The droplet entrainment is derived from a balance between the rate of atomization of the liquid layer flowing along the pipe wall and the rate of deposition of drops. When gas flow rate is low, gravity sedimentation controls the deposition rate, and when the gas phase at high flow velocity, droplet turbulent controls the deposition rate. At present most of the annular two-phase flow research focuses on the analysis of the main entrainment phenomenon. This article mainly discusses the entrained droplets from the gas liquid interface, because the entrained droplets plays an important role in a lot of flow parameters. Therefore, this article mainly from the droplet diameter and droplet entrainment velocity distribution and entrainment fraction three aspects to carry on the droplet entrainment characteristics research. Key words:gas-liquid two-phase flow;annular flow;entrained droplets;entrainment fraction