【作者】 余宇轩； 麻伟巍； 谢锡麟；

【Author】 YU Yu-xuan 1,MA Wei-wei 2,XIE Xi-lin 1 1 Department of Mechanics & Engineering Science,Fudan University,Shanghai 200433 2 College of Science,Donghua University,Shanghai 200051

【机构】 复旦大学力学与工程科学系； 东华大学理学院；

【摘要】 本实验研究低Reynolds数情形正交圆柱尾迹的空间动力学行为。涉及不同来流速度,不同圆柱间距工况下,几何中心层和剪切层上旋涡的空间演化特性。空间动力学行为分析,主要基于自谱、互谱的空间演化,并涉及空间相位分析。主要发现:正交圆柱尾迹,法向方向和展向方向的自谱演化不具有对称特性,分别表现为类单圆柱性和二次流现象;在正交圆柱中心附近,通过自谱图发现尾迹处存在旋涡的三次归并现象以及亚谐波的嵌入现象;通过互谱和空间相位分析,发现波数匹配现象对于正交圆柱来说只出现在平行涡和倾斜涡工况,并且其频带的中心恰为正交圆柱脱落主导频率。特别在平行涡工况下脱落主导频率和一阶亚谐波存在波数匹配现象。更多还原

【Abstract】 This experimental study was put emphasis on the spatial dynamical behaviors of two circular-cylinders forming a cross at low Reynolds number.It is involved in the vortices space evolution characteristics of the middle layer and the shear layor by the different flow speed and the different cylinder spacing conditions.The Spatial Dynamical Behavior analysis is mainly based on self-spectrum and cross spectrum,involving spatial phase analysis.The results are obtained by the self-spectrum that the normal direction and the spanwise direction do not have the symmetry of the direction in the wake of two circular cylinders arranged perpendicular to each other taht one is the wake of the vortex is similar to the single-cylinder and another is the secondary flow phenomenon. Near the center of structure the third mergence and embedding was found in the wake of the two circular cylinders by the self-spectrum picture,on the other hand,by the way of cross spectrum and the spatial phase analysis,the wave-number-matching phenomenon is only found in the laminar vortex shedding regime and Mode A.And the wave-number-matching phenomenon only exists around the shedding-frequency.In the laminar vortex shedding regime,it is found that the shedding-frequency and the first sub-harmonic wave have the same wave-number.更多还原