圆盘近尾迹中低频不稳定特性研究

摘要

Based on data of LES (large eddy simulation) and hot wire anemometry ,the low frequency instability in the near wake of a circular disk at Re=104 was studied by wavelet analysis and FFT method . It is found that ,besides Kelvin‐Helmholtz frequency StKH ≈1.6 and vortex shedding frequency StV ≈0.14 , there are two low frequencies ,namely StL1 ≈ 0.02 and StL2 ≈ 0.03 .Further study shows that the two frequencies are correlated with the azimuthal motion of the vortex shedding location and the pumping motion of the recirculation region , respectively . The study presents a reasonable explanation of the scattering in the value of the low frequency in the near wake of the bluff body .%利用大涡模拟（LES）和热线实验测量手段，采用小波分析及FFT 方法对 Re＝104的圆盘近尾迹中的特征频率进行了捕捉，着重对低频不稳定性进行了研究．L ES和热线实验结果表明，圆盘近尾迹中除对应于剪切层Kelvin‐Helmholtz不稳定的高频率 StKH ≈1.6和大尺度涡旋脱落频率S tV ≈0.14外，还存在两个低频率：S tL1≈0.02和 S tL2≈0.03．进一步对导致低频不稳定性的物理机制进行了分析，发现低频率 S tL1≈0.02与涡旋脱落周向旋转有关，而低频率 S tL2≈0.03与回流区的伸缩运动有关．本研究合理解释了目前钝体绕流低频数值分散的原因．