绝热层流泡状流运动的双流体模型

绝热层流泡状流是泡状流研究中的一个基础范例 .目前描述绝热层流泡状流常采用的双流体模型由于相间作用考虑欠缺而适用性差 .本文结合理论和实验研究结果导出了描述壁面“排斥”作用的表达式 ,并建立了一个封闭的双流体模型 .模型预测值和实验值的比较表明 ,由于相间作用的合理考虑 ,扩大了该模型的适用范围

TWO-FLUID MODEL FOR ADIABATIC LAMINAR BUBBLY FLOW

Adiabatic laminar bubbly flow is a basic problem in the research on bubbly flow. Published two-fluid models previously used to describe the flow are restricted to the flows within a limited bubble size range because these models do not reasonably take the interaction between the two phases into consideration. The universal basic averaged equations for bubbly flow were developed by applying the time averaging operator to the local instantaneous flow equations. According to analysis of the motion of bubbles in the flow field, the constitutive relations for interfacial momentum exchanges caused by interface-averaged stress,and interfacial momentum exchanges caused by asymmetric stress distributions on interfaces which include drag, virtual mass force, lift and wall-force were determined. A new formulation was proposed for wall force,which was derived from theoretic research and corrected by experimental data. Influence of bubble deformation on the flow was also considered as a correcting coefficient C w in the formulation of wall-force.The analysis of the stress in the phases indicated that the stress in gas phase is negligible in comparison with interactions between the phases. The shear stress in liquid phase was derived as an averaged liquid viscous stress term and the relation for the fluctuating stress in laminar bubbly flow was given.A closed two-fluid model was established to describe the flow.Comparison of the experimental data published in literature with the present model prediction showed that the present model can be applied to flows in a wider bubble size range due to the reasonable consideration of the near-wall effect.