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高紫涵, 程肖岐, 范子椰, 姜楠. 基于变间隔空间平均的等动量区分布研究. 力学学报, 待出版. DOI: 10.6052/0459-1879-24-098
引用本文: 高紫涵, 程肖岐, 范子椰, 姜楠. 基于变间隔空间平均的等动量区分布研究. 力学学报, 待出版. DOI: 10.6052/0459-1879-24-098
Gao Zihan, Cheng Xiaoqi, Fan Ziye, Jiang Nan. Investigation on the distribution of uniform momentum zones with variable-interval spatial average detection. Chinese Journal of Theoretical and Applied Mechanics, in press. DOI: 10.6052/0459-1879-24-098
Citation: Gao Zihan, Cheng Xiaoqi, Fan Ziye, Jiang Nan. Investigation on the distribution of uniform momentum zones with variable-interval spatial average detection. Chinese Journal of Theoretical and Applied Mechanics, in press. DOI: 10.6052/0459-1879-24-098

基于变间隔空间平均的等动量区分布研究

INVESTIGATION ON THE DISTRIBUTION OF UNIFORM MOMENTUM ZONES WITH VARIABLE-INTERVAL SPATIAL AVERAGE DETECTION

  • 摘要: 湍流边界层(TBL)中的相干结构是导致雷诺应力和湍动能产生的关键因素, 深入研究和理解其发展演化特性是有效控制湍流边界层的基础. 等动量区(UMZs)是湍流边界层中的典型大尺度相干结构, 其空间分布特性与湍流边界层中的其他相干结构之间的联系尚缺少有效认识和实验依据. 本文根据水洞实验中平板湍流边界层流法向平面中的大视场粒子图像测速仪(PIV)数据, 使用正负流向速度梯度下的变间隔空间平均(VISA)方法检测大尺度相干结构, 并研究其对等动量区空间分布的影响. 研究结果表明, 两种判定依据下的VISA检测所得流场中发卡涡头强度增大导致周围等动量区数量的增加, 且基于正流向速度梯度的VISA检测结果中等动量区数量显著大于基于负流向速度梯度的检测结果. 此外, VISA检测得到的低速结构附近等动量区的数量始终大于高速流体附近的等动量区数量, 且该规律与VISA检测过程中的流向速度梯度无关.

     

    Abstract: The coherent structures in the turbulent boundary layer (TBL) are of great importance for the generation of Reynolds stress and turbulent kinetic energy (TKE). It is essential for the effective control of the TBL to investigate the evolution of the coherent structures. Uniform momentum zones (UMZs) are typical large-scale coherent structures in the TBL, and the relationship between their spatial distribution and other coherent structures is still lack of comprehensive understanding and experimental evidence. In this work, the large-scale structures are detected through variable-interval spatial average (VISA) based on both positive and passive streamwise velocity gradients with particle image velocimetry (PIV) results, which have a large field of view and are achieved in the streamwise-wall-normal plane of a flat-plate TBL in the water tunnel. Subsequently, the influence of the structures on the spatial distribution of UMZs is studied. It is observed that the number of UMZs increases near the large-scale structures detected by VISA with both positive and passive streamwise velocity gradients due to the strengthened hairpin heads, while the number is always larger for the detection with positive streamwise velocity gradient. Furthermore, the UMZ number near the VISA-detected low-speed coherent structures is always larger than that around the high-speed region, which is independent on the streamwise velocity gradient during the VISA detection.

     

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