竖直槽道中泡状湍流的数值模拟研究

Numerical study of turbulent bubbly flows in a vertical channel

利用直接数值模拟技术计算研究了泡状槽道湍流问题,着重研究了当重力方向和流动方向反向(逆流方向)和同向(顺流方向)时气泡运动和湍流脉动的相互作用.比较了泡状槽道湍流和纯剪切槽道湍流的流场统计特性,分析了气泡在流场中的分布规律,讨论了气泡在湍流流场中的脉动运动特性及其对湍流近壁结构的影响.计算结果表明,逆流泡状槽道湍流中,气泡增强流体运动,湍流的统计特性增强;而在顺流情况下,气泡对流体运动的作用相反.

Direct numerical simulations have been used to study turbulent bubbly flows in a vertical channel.The effect of bubble motions on the turbulent fluctuations was examined for the turbulent bubbly flows when the direction of gravity is aligned with/against the mean flow.Turbulence statistics for the turbulent bubbly channel flows were given and compared with those of pure-shear channel flow.Some typical results,such as the concentration and velocity fluctuations of bubble phase,and the near-wall coherent structures,were exhibited and analyzed.It is found that when the direction of gravity is against the mean flow,the turbulence statistics are enhanced by the bubble motion.The effect of bubble motion is to suppress the turbulent fluctuation when the direction of gravity is aligned with the mean flow.