低浓度固液两相流相间阻力修正模型研究

Modified Interphase Drag Model for Diluted Solid-Liquid Two-phase Flow

低浓度固液两相流的相间阻力是影响固相浓度分布计算结果的重要因素。常用于固液两相流数值计算的Wen-Yu模型中,阻力系数是通过标准阻力系数曲线中添加浓度的影响得到的,并没有考虑湍流对阻力系数的影响。由于这一影响是惯性效应和湍动效应的综合体现,针对低浓度含沙水流,研究通过引入惯性因子和湍动因子来分别表达惯性项、湍流强度对阻力系数的影响。根据试验和理论研究,提出了湍流修正函数与惯性因子、湍动因子的表达式形式;利用试验数据并结合最小二乘法,确定了表达式系数,得到了湍流修正函数与颗粒雷诺数、湍流强度的关系式。通过对圆管内低浓度含沙水流的计算表明,运用湍流修正函数修正后的Wen-Yu模型,在不同的进口水流速度下,计算得到的固相浓度分布更接近试验结果。

The interphase drag for diluted solid - liquid two-phase flow is important for solid volume concentration calculation. The Wen- Yu drag model is widely used in solid- liquid two-phase flow numerical simulation. However, the drag coefficient in Wen - Yu drag model was obtained by adding concentration variable to standard drag coefficient curve, and the influence of fluid turbulence on drag coefficient was ignored. Thus, the influence of fluid turbulence on drag coefficient was considered. The inertia factor and turbulence factor were introduced to describe influence of inertia term and turbulence intensity on drag coefficient respectively for diluted solid- liquid two-phase flow, since the influence was caused by inertia effect and turbulence effect. According to experimental and theoretical investigations, a formula form between turbulence modified function and the two factors was proposed. The constant coefficients in the correlation were determined by the least square method using experimental data, then the relation between turbulence modified function and particle Reynolds number, turbulence intensity was obtained. The turbulence modified function was then used to modify Wen- Yu model. A two-phase flow simulation was conducted in a circular tube with modified Wen - Yu model. By comparison with Wen - Yu model, the results showed that the computed solid concentration distributions of modified Wen - Yu model were agreed well with experimental data at different inlet fluid velocities.