切角率对方柱绕流特性的影响规律及其机理

Effects of Chamfer Ratio on Flow Around a Square Cylinder and Their Mechanism

摘要:

采用大涡模拟方法，在雷诺数2.2×10⁴、均匀来流和全风向角下，研究了方柱气动性能和绕流形态随切角率（0、1/14、1/7、2/7）的变化规律。与标准方柱相似，随着风向角的增大，切角方柱周围流场依次呈现“前角分离流态”、“分离泡流态”和“附着流流态”等三种流态。随着切角率的增大，切角方柱整体上呈现平均阻力系数减小、斯托罗哈数增大的趋势。小风向角下（α < 10°），切角方柱的平均升力系数和脉动升力系数随切角率显著减小；大风向角下（α > 25°），大切角率（2/7）方柱的升力系数大于标准方柱。在前角分离流态和分离泡流态之间的临界风向角附近，切角方柱的平均阻力系数和脉动升力系数均达到极小值，平均升力系数和斯托罗哈数达到极大值。随着切角率的增大，不同风向角下的切角方柱尾流宽度有变窄的趋势，但方柱尾流涡脱强度的变化较为复杂。

Abstract:

This study investigates the aerodynamic performances and flow patterns of square cylinders with various chamfer ratios （0， 1/14， 1/7， and 2/7） using the large-eddy simulation （LES） method.The analysis is conducted at Reynolds number of 2.2 ×10⁴， with a uniform inflow condition and different incidence angles. Similar to the flow past a standard square cylinder， the chamfered square cylinders exhibit three distinct flow patterns as the incidence angle increases： the “leading-edge separation mode”， the “separation bubble mode”， and the “attached flow mode”. As the chamfer ratio increases， the square cylinders exhibit a general trend of decreasing mean drag coefficient and an increasing Strouhal number. At small incidence angles （α < 10°）， square cylinders with higher chamfer ratios experience significant reductions in both the mean land fluctuating lift coefficients. However， at large incidence angles （α > 25°）， the square cylinder with a larger chamfer ratio （2/7） has a higher lift coefficient compared to the standard square cylinder. The mean drag coefficient and fluctuating lift coefficient of the square cylinder reach their minimum values near the critical incidence angle between the leading-edge separation and separation bubble modes， while the mean lift coefficient and the Strouhal number reach their maximum values. As the chamfer ratio increases， the wake width of the square cylinders in different incidence angles generally narrows. However， the variation in the strength of the wake vortices is more complex.