竖直管中流体差异引起的混合特性研究

Research on the Mixing Characteristic of Fluids with Property Difference in Vertical Tube

为了研究竖直管中2种不同流体在重力作用下的混合特性,基于Mixture多相流模型和PISO算法对混合过程进行计算流体动力学数值模拟,分析了混合流动特性。结合交联液成胶的浓度要求,确定了交联液和压井液两端的混合速度,进一步研究了密度差及黏度差对混合速度的影响规律。研究结果表明,密度较大的压井液沿管壁呈环状流混入交联液内部,而密度较小的交联液沿着中心轴线连续流入压井液内部不断混合,使得交联液的浓度及有效长度显著下降;当交联液密度由1 020 kg/m3增大到1 130 kg/m3、黏度从0.05 Pa·s提高到0.11 Pa·s时,在交联液端和压井液端分别具有较大的混合速度下降比例,分别为53.8%和31.2%。该项研究结果为调整交联液配方的基本性能提供了参考,有助于胶体抗压强度的提高。

To study the mixing characteristic of two types of fluid in vertical tube under the effect of gravity, a CFD numerical simulation of the mixing process was conducted on the basis of the Mixture muhiphase flow model and the PISO algorithm. The mixing flow characteristic was analyzed. In combination with the concentration require- ment of crosslinked fluid gelatinization, the mixing velocity on both ends of crosslinked fluid and kill fluid was （le- termined. A further study of the influence law of density difference and viscosity difference on mixing veloeity was carried out. The research findings show that kill fluid with considerable density mixes into crosslinked fluid in tile form of annular flow along pipe wall. The crosslinked fluid with small density flows into kill fluid continuously and mixes with it constantly ahmg the central axis, making the concentration and effective length of crosslinked fluid de- crease remarkably. When the density of crosslinked fluid increases from 1 020 to 1 130 kg/m3 , and its viscosity in- creases from O. 05 to 0. 11 Pa · s, the decreasing proportions of mixing velocity are remarkable on the ends of crosslinked fluid and kill fluid respectively, which are 53.8% and 31.2%. The research achievement can provide a reference to adjustment of the basic property of crosslinked fluid formula. It is helpful to the improvement of gel＇ s compression strength.