Local dynamic perturbation effects on the scale interactions in wall turbulence
Local dynamic perturbation effects on the scale interactions in wall turbulence
复制标题
局部动态扰动对壁湍流尺度相互作用的影响
DOI：
10.1080/14685248.2020.1864388
复制
发表时间：
2020
影响因子：
1.9
通讯作者：
Xiaobo Zheng
中科院分区：
文献类型：
--
作者：
Zhanqi Tang;Xingyu Ma;Nan Jiang;Xiaotong Cui;Xiaobo Zheng
本文介绍了在确定性强迫输入下近壁尺度相互作用的实验研究。外部强迫输入由壁装压电（PZT）致动器产生，它直接将动态扰动引入湍流边界层流动的近壁循环。速度波动的频谱表明，在所有的扰动情况下，可以观察到的基本强迫模式和高阶谐波的发生是依赖于PZT扰动振幅。在强强迫输入下，大尺度结构通过高度振幅调制（AM）效应影响基本强迫模态。更重要的是，发现了高次谐波和小尺度湍流的相位切换过程，它们在y+ λ x<10时与强迫模式同相，在20 λ x<y+ λ x<50时切换为异相。结果表明，强迫模式重新安排的谐波和小尺度湍流在近壁区，证明了AM效应和相位关系。此外，偏度跨项分布证实了近壁尺度重排。
An experimental investigation of near-wall scale interactions in the presence of a deterministic forcing input is presented in this work. The external forcing input was generated by a wall-mounted piezoelectric (PZT) actuator, which directly introduces a dynamic perturbation into the near-wall cycle of turbulent boundary layer flow. The spectra of velocity fluctuations indicated that the fundamental forcing mode can be observed in all the perturbed cases and that the occurrence of high-order harmonics is dependent on the PZT perturbation amplitude. Under the strong forcing input, the fundamental forcing mode is influenced by large-scale structures through a high-degree amplitude modulation (AM) effect. More importantly, the phase-switching process was found for the high-order harmonics and small-scale turbulence, both of which are in phase with the forcing mode in y+∼x<10 and are switched to be out of phase in 20∼x<y+∼x<50. It was demonstrated that the forcing mode rearranges both the harmonics and small-scale turbulence in the near-wall region, as evidenced by the AM effect and phase relationship. In addition, the near-wall scale rearrangements were confirmed by the skewness cross-term distribution.