Key Lab of Micro/Nano Systems for Aerospace, Ministry of Education, Northwestern Polytechnical University, Xi'an710072, P. R. China.
Shaanxi Key Lab of MEMS/NEMS, Northwestern Polytechnical University, Xi'an710072, P. R. China.
Langmuir. 2022 Dec 20;38(50):15570-15578. doi: 10.1021/acs.langmuir.2c02222. Epub 2022 Dec 8.
Biomimetic riblet surfaces, such as blade, wavy, sinusoidal, and herringbone riblet surfaces, have widespread applications for drag reduction in the energy, transportation, and biomedicine industries. The drag reduction ability of a blade riblet surface is sensitive to the yaw angle, which is the angle between the design direction of the riblet surface and the average flow direction. In practical applications, the average flow direction is often misaligned with the design direction of riblet surfaces with different morphologies and arrangements. However, previous studies have not reported on the drag reduction characteristics and regularities related to the yaw angle for surfaces with complex riblet microstructures. For the first time, we systematically investigated the aerodynamic drag reduction characteristics of blade, wavy, sinusoidal, and herringbone riblet surfaces affected by different yaw angles. A precisely adjustable yaw angle measurement method was proposed based on a closed air channel. Our results revealed the aerodynamic behavior regularities of various riblet surfaces as affected by yaw angles and Reynolds numbers. Riblet surfaces with optimal air drag reduction were obtained in yaw angles ranging from 0 to 60° and Reynolds numbers ranging from 4000 to 7000. To evaluate the effects of the yaw angle, we proposed a criterion based on the actual spanwise spacing () of microstructure surfaces with the same phase in a near-wall airflow field. Finally, we established conceptual models of aerodynamic behaviors for different riblet surfaces in response to changes in the airflow direction. Our research lays a foundation for practical various riblet surface applications influenced by yaw angles to reduce air drag.
仿生肋纹表面，如叶片型、波浪型、正弦型和人字形肋纹表面，在能源、交通和生物医学等行业的减阻方面有着广泛的应用。叶片肋纹表面的减阻能力对迎角（肋纹表面设计方向与平均流动方向之间的夹角）很敏感。在实际应用中，平均流动方向经常与具有不同形态和排列的肋纹表面的设计方向不重合。然而，以前的研究尚未报道过与具有复杂肋纹微观结构的表面的迎角相关的减阻特性和规律。我们首次系统地研究了不同迎角对叶片型、波浪型、正弦型和人字形肋纹表面的空气动力减阻特性的影响。基于封闭空气通道，提出了一种精确可调迎角测量方法。我们的结果揭示了各种肋纹表面在迎角和雷诺数影响下的空气动力行为规律。在迎角为 0 至 60°、雷诺数为 4000 至 7000 的范围内，获得了具有最佳空气减阻效果的肋纹表面。为了评估迎角的影响，我们提出了一个基于近壁流场中具有相同相位的微观结构表面实际展向间距 () 的准则。最后，我们建立了不同肋纹表面在气流方向变化时的空气动力行为概念模型。我们的研究为受迎角影响的各种实际肋纹表面应用奠定了基础，以减少空气阻力。
