双流体颗粒-壁面碰撞模型在突扩两相湍流模拟中的应用

Application of the Two-Fluid Particle-Wall Collision Model for Simulating the Sudden Expansion Two-Phase Turbulence

由于壁面粗糙度的双流体颗粒 壁面碰撞模型中,没有考虑颗粒 壁面碰撞前后颗粒速度相对于平均速度的差别,因此,修正了由此引起的颗粒雷诺应力的变化,并应用其对轴对称突扩流动进行了数值模拟,着重探讨了不同颗粒相边界条件的影响.结果表明,由于考虑了各方向雷诺应力之间的相互转化、雷诺应力从平均运动中得到能量以及壁面对颗粒运动的衰减作用等因素,包括摩擦系数、恢复系数和壁面粗糙度等影响因素的颗粒 壁面碰撞模型和由此得到的简化模型,给出的结果与实验值符合较好,而通常使用的零梯度颗粒壁面边界条件则给出失真的模拟结果.

The two-fluid particle-wall collision model accounting for wall roughness was modified by taking into account the change of particle Reynolds stresses due to the difference between the velocities before and after collision and their mean value, and axisymmetric sudden expansion flows were simulated. The result shows that the collision model, accounting for the friction coefficient, restitution coefficient and wall roughness, reflects the redistribution of Reynolds stress in different directions on the wall, the absorption of turbulent energy from the mean flows and attenuation of particle motion by the wall, it gives better results than the over-simplified zero-gradient boundary conditions. In addition, for sudden expansion flows the simplified condition from the collision model can also give reasonable result than that given by the oversimplified zero-gradient boundary conditions.