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崔光耀, 潘翀, 高琪, 李鹿辉, 王晋军. 沟槽方向对湍流边界层流动结构影响的实验研究[J]. 力学学报, 2017, 49(6): 1201-1212. DOI: 10.6052/0459-1879-17-252
引用本文: 崔光耀, 潘翀, 高琪, 李鹿辉, 王晋军. 沟槽方向对湍流边界层流动结构影响的实验研究[J]. 力学学报, 2017, 49(6): 1201-1212. DOI: 10.6052/0459-1879-17-252
Cui Guangyao, Pan Chong, Gao Qi, Akira Rinoshika, Wang Jinjun. FLOW STRUCTURE IN THE TURBULENT BOUNDARY LAYER OVER DIRECTIONAL RIBLETS SURFACES[J]. Chinese Journal of Theoretical and Applied Mechanics, 2017, 49(6): 1201-1212. DOI: 10.6052/0459-1879-17-252
Citation: Cui Guangyao, Pan Chong, Gao Qi, Akira Rinoshika, Wang Jinjun. FLOW STRUCTURE IN THE TURBULENT BOUNDARY LAYER OVER DIRECTIONAL RIBLETS SURFACES[J]. Chinese Journal of Theoretical and Applied Mechanics, 2017, 49(6): 1201-1212. DOI: 10.6052/0459-1879-17-252

沟槽方向对湍流边界层流动结构影响的实验研究

FLOW STRUCTURE IN THE TURBULENT BOUNDARY LAYER OVER DIRECTIONAL RIBLETS SURFACES

  • 摘要: 本文采用时间解析的二维粒子图像测速技术,对零压力梯度光滑以及汇聚和发散沟槽表面平板湍流边界层统计特性和流动结构进行了研究.结果表明在垂直于汇聚和发散沟槽表面的对称平面内,相对于光滑壁面,发散沟槽壁面使当地边界层厚度、壁面摩擦阻力、湍流脉动、雷诺应力等明显减小;而汇聚沟槽壁面对湍流边界层特性和流动结构的影响正好相反,汇聚沟槽使壁面流体有远离壁面向上运动的趋势,因而导致边界层厚度增加了约43%;同时,在汇聚沟槽表面情况下流向大尺度相干结构更容易形成,这对减阻是不利的.此外,顺向涡数量在湍流边界层的对数区均存在一个极大值,发散沟槽表面所对应的极大值位置更靠近沟槽壁面,而在汇聚沟槽表面则有远离壁面的趋势,由顺向涡诱导产生的较强的喷射和扫掠运动会在湍流边界层中产生较强的剪切作用,顺向涡数量的减少是发散沟槽壁面当地摩擦阻力降低的主要原因.

     

    Abstract: The statistical characteristics and flow structures for turbulent flow over smooth, convergent and divergent riblets flat plate with zero pressure gradient are investigated with two-dimensional time-resolved particle image velocimetry (TRPIV). It is shown in the wall-normal planes of the convergent and divergent riblets flat plate that, compared to the smooth flat plate, the local boundary layer thickness, wall friction velocity, turbulent fluctuation and Reynolds stress are evidently reduced over the divergent surface. Furthermore, the effect of convergent riblets flat plate on turbulent boundary layer flow is different from the divergent one, which causes the near wall fluid move away and results in an increment of about 43% for turbulent boundary layer thickness. Meanwhile, the large scale coherent structures are more likely to be formed for flow over convergent riblets surface, this is not benefit for drag reduction. Besides, the population of the prograde vortices reaches a maximum value in the log region of turbulent boundary layer, and which appears much closer to the divergent riblets surface than the convergent one. The ejection and sweep induced by the prograde vortices make a great contribution to the mean shear in turbulent boundary layer, and it is the decrease of the prograde vortices which results in the reduction of the wall friction for the diverqent riblets surface.

     

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