脉动流条件下圆柱绕流特性研究

该文数值研究了脉动流条件下圆柱绕流场特性，对涡量分布、升阻力系数、升力系数频谱特性等进行了分析。结果表明，脉动流作用会使圆柱尾涡剪切层变薄，提高脉动频率使尾涡长度变短、脱离加快，提高无量纲脉动振幅使主导涡的脱落速度降低，使旋涡生成区域更靠近圆柱表面；脉动频率与无量纲脉动振幅的增大使升、阻力系数的振幅均增大，而且与升力系数相比，阻力系数的振幅更大，变化更快；升力系数频谱图存在多个主频，包括旋涡脱落频率和相位叠加频率，其中旋涡脱落频率的振幅随着脉动频率的增加而减小，随着无量纲脉动振幅的增加而增加。

Investigation on Flow Characteristic of Flowing around a Circular Cylinder under the Pulsating Flow Condition

A numerical simulation for the flow characteristics of flowing around a circular cylinder under the pulsating flow condition was carried out. The study focuses on vorticity distribution, lift coefficient, resistance coefficient and frequency spectrum of lift coefficient. Results indicate that the shear layer of wake vortex is thinner when the pulsating flow goes around a circular cylinder. The length of wake vortex shortens and the detachment of vortex accelerates as the pulsation frequency of the pulsating flow increases. The amplitude of lift coefficient and resistance coefficient both increase with the rising of the pulsation frequency and the dimensionless pulsation amplitude. The latter is larger and varies more quickly than the former. There exist several basic frequencies in frequency spectrogram of lift coefficient, including the vortex shedding frequency and the frequencies obtained by phase superposition. The amplitude of the vortex shedding frequency decreases with the pulsation frequency increase, whereas increases with the dimensionless pulsation amplitude increase.