阻流比对平行壁面间圆柱绕流尾迹演化的影响

Effect of blockage ratio on circular cylinder wake evolution between parallel walls

为了揭示阻流比对圆柱绕流尾迹演化特性的影响,采用多块O型网格,对低雷诺数下较宽阻流比范围的平行壁面间圆柱绕流进行数值模拟研究,讨论不同阻流比下壁面对圆柱绕流尾迹形态和尾迹转捩的影响,得到尾迹转捩临界雷诺数、双子涡和旋涡脱落的特征参数。研究结果表明:圆柱绕流尾迹转捩和尾迹形态受阻流比影响显著,尾迹转捩的第一、第二临界雷诺数随阻流比而增加,当阻流比超过临界值后,尾迹中出现2个附着于壁面的回流区;斯特劳哈尔数和阻力系数均值随阻流比而增加,而升力系数均方根在不同阻流比范围内则呈现出不同的变化规律。

To identify the effect of blockage ratio on the evolution of circular cylinder wake, numerical simulation of the flow over a circular cylinder between parallel walls was conducted using a multi-block O-type grid at low Reynolds numbers and a wide range of blockage ratios. The effect of different blockage ratios on the evolution of circular cylinder wake between parallel walls was analyzed and discussed. Critical Reynolds numbers for flow transition, twin vortex properties and vortex shedding features were obtained for different blockage ratios. The results show that the transitions and characteristics of the wake are markedly affected by the blockage ratio. The 1st and 2nd critical Reynolds numbers for flow transition increase with blockage ratio. When the blockage ratio surpasses a critical value, two circulation regions can be observed on the walls on either side of the wake. The Strouhal numbers and average drag coefficients both increase with blockage ratio. However, the root mean squares of lift coefficients vary with different blockage ratios.