人工合成微射流周期吹吸扰动控制壁湍流相干结构的实验研究
Experimental investigation on active control of coherent structure in wall-bounded turbulence with periodic blow-suck disturbance by submerged micro-synthetic jet flow
Received:February 02, 2023  Revised:April 03, 2023
DOI:10.7520/1001-4888-23-022
中文关键词:  湍流边界层  合成微射流  条件相位平均  VITA法  子波分析
英文关键词:turbulent boundary layer  micro-synthetic jet flow  conditional sampling phase-lock average  VITA method  wavelet analysis
基金项目:国家自然科学基金项目(11972251, 12172242, 12202309, 12202310);中德合作研究小组基金项目(GZ1575);中国博士后基金项目(2022M712357)
Author NameAffiliation
GAO Saipeng Department of Mechanics, School of Mechanical Engineering, Tianjin University, Tianjin 300354, China 
BAI Jianxia Mathematics Teaching Department of Tianjin Ren'ai University, Tianjin 301636, China 
CHENG Xiaoqi Department of Mechanics, School of Mechanical Engineering, Tianjin University, Tianjin 300354, China 
TIAN Haiping Department of Mechanics, Taiyuan University of Technology, Taiyuan 030024, Shanxi, China 
JIANG Nan* Department of Mechanics, School of Mechanical Engineering, Tianjin University, Tianjin 300354, China 
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中文摘要:
      湍流的壁面摩擦阻力与壁湍流相干结构的猝发过程有重要关系。减少壁面摩擦阻力的方法之一,就是通过对壁湍流的相干结构进行控制实现的。为探究人工合成微射流的减阻效果,通过控制镶嵌在壁面空腔上的压电振子进行周期振荡,在壁面产生人工合成微射流,实现壁湍流结构猝发主动控制。利用单丝边界层热线探针,对施加人工合成微射流扰动前后平板湍流边界层的流向速度信号进行测量;利用子波变换和能量最大尺度准则提取出最大含能尺度脉动速度信号的骨架后,通过自相关法确定VITA法的平均周期T和门限值K;利用VITA法对湍流脉动速度信号进行检测,得到相干结构猝发的条件相位平均波形。研究结果表明,施加一定频率和振幅的人工合成微扰动以后,湍流边界层平均速度剖面的黏性底层增厚,对数律层上移。人工合成微射流能够抑制近壁相干结构的猝发,使近壁相干结构的振幅明显降低,从而产生减阻效果。同时,人工合成微射流只能控制近壁区域相干结构猝发,在远离壁面区域无法产生控制效果。
英文摘要:
      By controlling the periodic oscillation of piezoelectric vibrators embedded in the wall cavity, an artificial synthetic microjet is generated on the surface of the wall, and the open-loop active control of coherent structure bursts in the turbulent boundary layer on a flat plate is realized. The instantaneous velocity signals at different wall-normal positions of the turbulent boundary layer are measured with a mini hot-wire boundary probe of anemometer before and after the micro-jet disturbance superposed. The wavelet transform and the maximum energy criterion are employed to extract the skeleton of the fluctuating velocity signals at the most energetic scale. The short average period T and the threshold level K of VITA method is determined by the maximum energy criterion and the autocorrelation function of the wavelet coefficients at the most energetic scale. Finally, the burst events of coherent structures are detected from the time series signals of fluctuating velocity by VITA scheme and the eigen-waveform of coherent structure bursts is obtained by phase-locked average of the detected segments of fluctuating velocity signals. The results demonstrate that the active control strategy of the artificial synthetic microjet can make the buffer sublayer thicker and lift the logarithmic law sublayer of the mean velocity profile up with drag reduction effect. By comparing the eigen-waveform of the coherent structure burst before and after the active control strategy of the artificial synthetic microjet performing, it is confirmed that the amplitude of the eigen-waveform of the coherent structure in the near-wall region is significantly depressed, which indicating that the active control strategy can suppress the burst of the coherent structure in the near-wall region while it is invalid in the outer region of the turbulent layer.
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