不同排列方式下双方柱绕流的同步现象及相位特征研究

Synchronization and Phase Dynamics of Flow Around Two Square Cylinders in Various Arrangements

该文采用二维直接数值模拟方法研究了雷诺数Re=100时,双方柱系统在不同形心间距比(P~*=1.5~5,其中P~*=P/D,P为方柱形心间距,D为方柱边长)和来流攻角(α=0°~90°)条件下的流动同步特性。研究首先基于频谱分析与相位动力学分析了升力系数特征,据此划分双方柱流动的同步模态,并对其尾流场演化特征进行了探讨。随后重点研究了P~*和α参数对同步模态和相位特征的影响规律。研究发现双方柱绕流存在1/1同步、p/p同步(p为大于1的正整数)、p/q同步(q为不等于p的正整数)、准周期和非同步流动模态,其对应的相位特征分别为相位锁定、相位捕获、相位漂移、相位漂移和滑移以及其他状态。结果显示:在α≤35°的区域,流动以1/1同步为主;在α>35°的区域,P~*>2.5时,流动以准周期为主,P~*≤2.5时,流动以非同步为主。

Synchronization modes of the flow around two square cylinders with different pitch ratios(P~*=1.5~5.0, where P~*=P/D, P is the centroid spacing of the square cylinder, and D is the side length of the square cylinder) and incidence angle(α=0°~90°) are investigated using two-dimensional direct numerical simulation at Re=100. The characteristics of lift coefficients are analyzed by using spectrum analysis methods and phase dynamics theory, following by a discussion on the identification of flow synchronization and the wake evolution of the square cylinders. The effects of P~* and α on the synchronization modes, phase dynamics and transition patterns are then examined. The 1/1, p/p(p is a positive integer greater than 1) and p/q(q is a positive integer not equal to p)synchronization modes, quasiperiodic mode and desynchronization mode of flows are observed, corresponding to the phase locking,phase trapping, phase drifting, phase drifting and slipping, as well as other states, respectively. When α≤35°, the 1/1 synchronization is the dominant mode in the regime map. When α>35° and P~*>2.5, most of the cases are quasiperiodic modes, while those are mainly characterized by the desynchronization mode when α>35° and P~*≤2.5.