重力场对竖直管段两种油品紊流传质特性影响的分析

Effect Analysis of Gravity on Mass Transfer with Two Petroleum Products in Erect Pipeline

在考虑重力影响的情况下,从动量-质量传递耦合着手,采用κ-ε紊流模式理论,建立起顺序输送管内非稳态油品传质数学模型,并对该模型进行数值求解,计算结果清晰地反映出管内两种油品交界面处的对流扩散传质现象。同时模拟结果表明,竖直管段中密度差对混油的影响在层流底层表现比较明显,对混油尾影响较大;密度较大的油品在管段上方时,重力场的作用使得紊流核心区的混油界面向前推移,但层流底层形成的混油尾长度明显拉长,当油品速度增加时,紊流脉动强度增加,混油尾长度将减小;通过竖直下坡管道分析,发现竖直管道中密度差对混油的影响大于粘度差对混油的影响,竖直管段密度差对混油的影响不可忽略。

Under the situation of considering gravity effect, the unsteady mass transfer mathematic model within batch pipeline is set up based on momentum transfer and mass transfer equations and K - ε turbulent pattern theory. Numerical simulation for this model has been investigated. Simulation result can reflect the phenomenon of mass transfer in two kinds of oil interface. At the same time, it indicates that the effect of density to laminar bottom and contamination tail in erect pipeline is distinct. When bigger density oil is on the top of pipeline, contamination interface in core area of turbulent flow develops forward due to the effect of the gravity field and the elongated length of contamination tail. While oil product speed is increased, turbulent intensity is increased and the length of contamination tail is reduced. The conclusion is that the effect of density to laminar bottom layer in vertical pipeline is bigger than that of viscosity obtained through analyzing erect downgrade pipeline. Thus, it can not be ignored.