Convection of multi-scale motions in turbulent boundary layer by temporal resolution particle image velocimetry
Convection of multi-scale motions in turbulent boundary layer by temporal resolution particle image velocimetry
复制标题
时间分辨率粒子图像测速研究湍流边界层多尺度运动对流
DOI：
10.1080/14685248.2022.2071429
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发表时间：
2022
影响因子：
1.9
通讯作者：
Nan Jiang
中科院分区：
文献类型：
--
作者：
Ziye Fan;Zhanqi Tang;Xingyu Ma;Nan Jiang
为了研究湍流结构的对流特性和泰勒假设的正确性，进行了湍流边界层中的粒子图像测速实验。(，边界层厚度)的视图是由四个流向排列的摄像机拍摄的。通过连续波变换研究了流向湍动能在流向尺度上的分布，发现在流向湍动能最大处存在尺度。脉动速度(时间维度上的瞬时速度减去平均速度)被分为大尺度运动(LSM)和小尺度运动(SSM)部分，以。用时空相关法确定了LSM和SSM的对流速度，它们在近壁区大于局地平均速度，但在尾流区小于局地平均速度。用自相关方法比较了泰勒假设重建的速度场与原始场的统计特性，发现重建后的速度场的模式比原始场的模式长，但其高度没有明显的差别。原始速度场与重建场的相关分析表明，对于给定阈值(相关系数C= 0.6)的区域，在流向对流分离中，最小二乘法能保持较高的速度场，而最小二乘法能较好地保持最小二乘法。
Experiments of particle image velocimetry (PIV) in the turbulent boundary layer athave been conducted to investigate the convection characteristic of turbulent structure and the validity of Taylor’s hypothesis. Views of(, the boundary layer thickness) were captured by four streamwise-arranged cameras. Distributions of streamwise turbulent kinetic energy on a streamwise scale were investigated by continuous-wave transform, and scales were found where the portion of streamwise turbulent kinetic energy approaches maximum. Fluctuating velocities (instant velocity minus average velocity on time dimension) were divided into large-scale motion (LSM) and small-scale motion (SSM) portions, bounded by. Convection velocities of LSM and SSM are determined by the spatiotemporal correlation method, and they are larger than local average velocities in near-wall regions, but smaller than local average velocities in wake regions. Statistical characteristics between velocity fields reconstructed by Taylor’s hypothesis and original fields were compared by the autocorrelation method, and the reconstructed field’s patterns are longer than original field’s patterns, while their heights do not have clear distinction. The correlation of original velocity fields and reconstructed fields shows that LSM can hold on overand SSM overin streamwise convection separation for regions of, given a threshold value (correlation coefficientC= 0.6).