Active control of multiscale features in wall-bounded turbulence

• Published in: Acta mechanica Sinica Vol. 36; no. 1; pp. 12 - 21
• Main Authors: Cui, Xiaotong, Jiang, Nan, Zheng, Xiaobo, Tang, Zhanqi
• Format: Journal Article
• Language: English
• Published: Beijing The Chinese Society of Theoretical and Applied Mechanics; Institute of Mechanics, Chinese Academy of Sciences 01.02.2020; Springer Nature B.V; Department of Mechanics,Tianjin University,Tianjin 300354,China%Department of Mechanics,Tianjin University,Tianjin 300354,China; Tianjin Key Laboratory of Modern Engineering Mechanics,Tianjin 300354,China%School of Naval Architecture Ocean & Civil Engineering,Shanghai Jiao Tong University,Shanghai 200240,China
• Edition: English ed.
• Subjects: Active control; Actuators; Boundary layer flow; Buffer layers; Classical and Continuum Physics; Computational Intelligence; Discrete Wavelet Transform; Distribution functions; Engineering; Engineering Fluid Dynamics; Flatness; Flow control; Fluid dynamics; Fluid flow; Intermittency; Multiscale analysis; Perturbation; Piezoelectricity; Probability distribution functions; Research Paper; Statistical analysis; Theoretical and Applied Mechanics; Turbulence; Turbulent boundary layer; Turbulent flow; Variation; Velocity distribution; Vibration; Turbulent boundary layer; Bursting process; Piezoelectric actuator; Drag reduction; Discrete wavelet decomposition
• ISSN: 0567-7718; 1614-3116
• DOI: 10.1007/s10409-019-00907-5

This study experimentally investigates the impact of a single piezoelectric (PZT) actuator on a turbulent boundary layer from a statistical viewpoint. The working conditions of the actuator include a range of frequencies and amplitudes. The streamwise velocity signals in the turbulent boundary layer flow are measured downstream of the actuator using a hot-wire anemometer. The mean velocity profiles and other basic parameters are reported. Spectra results obtained by discrete wavelet decomposition indicate that the PZT vibration primarily influences the near-wall region. The turbulent intensities at different scales suggest that the actuator redistributes the near-wall turbulent energy. The skewness and flatness distributions show that the actuator effectively alters the sweep events and reduces intermittency at smaller scales. Moreover, under the impact of the PZT actuator, the symmetry of vibration scales’ velocity signals is promoted and the structural composition appears in an orderly manner. Probability distribution function results indicate that perturbation causes the fluctuations in vibration scales and smaller scales with high intensity and low intermittency. Based on the flatness factor, the bursting process is also detected. The vibrations reduce the relative intensities of the burst events, indicating that the streamwise vortices in the buffer layer experience direct interference due to the PZT control.