In order to manipulate large-scale coherent structures in the wall-bounded turbulence and reduce the skin-friction, an active-control experimental investigation was performed through synchronous and asynchronous vibrations of double piezoelectric vibrators embedded spanwisely on a smooth flat plate surface. A TSI-IFA300 hot-wire anemometer and TSI-1621A-T1.5 hot-wire probe were used to measure the time series of instantaneous velocity at different locations. Influence of the vibrations on wall-bounded turbulence are compared in a multi-scale point of view. A disturbance Reynolds Number Re_d = ρd²f/μ is introduced to represent the disturbance. A probability density functions (PDFs) of the multi-scale components of the turbulence velocity and multi-scale conditional phase-averaged waveform are studied in detail using the Wavelet transform. The results show that the maximum drag reduction rate 18.54% was obtained at 100V/160Hz and Re_d = 0.54 case with an asynchronous vibration mode. The disturbances generated by the vibrators have a significant influence on the sweep events of burst. The asynchronous vibration model is more effective than synchronous vibration one. A possible physical mechanism is recognized to explain why the disturbance frequency of 160Hz leads to an optimal parameter set for drag reduction.

中文翻译：

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双压电振动器主动控制减壁湍流阻力的实验研究

为了控制壁面湍流中的大规模相干结构并减少蒙皮摩擦，通过将双压电振子沿纵横向嵌在光滑平板表面上的同步和异步振动进行主动控制实验研究。使用TSI-IFA300热线风速仪和TSI-1621A-T1.5热线探头测量不同位置的瞬时速度的时间序列。从多尺度的角度比较了振动对边界湍流的影响。甲干扰雷诺数重新_d = ρd ² F /μ引入来表示干扰。使用小波变换详细研究了湍流速度和多尺度条件相位平均波形的多尺度分量的概率密度函数（PDFs）。结果表明，在异步振动模式下，在100V / 160Hz和Re _d = 0.54的情况下，最大减阻率为18.54％。振动器产生的干扰对突发的扫描事件有重大影响。异步振动模型比同步振动模型更有效。人们认识到一种可能的物理机制来解释为什么160Hz的干扰频率会导致最佳的减阻参数集。