### 微吹气对湍流平板边界层流动特性的影响及其减阻机理

1. 浙江大学 航空航天学院, 杭州 310027
• 收稿日期:2020-01-09 修回日期:2020-03-02 发布日期:2020-02-27
• 通讯作者: 张阳 E-mail:yangzhang@zju.edu.cn
• 基金资助:
中华人民共和国工业和信息化部-欧盟委员会航空科技合作项目（690623）

### Micro-blowing: Effect on flow characteristics in turbulent flat plate boundary layer and drag reduction mechanism

FAN Yuntao, ZHANG Yang, YE Zhixian, ZOU Jianfeng, ZHENG Yao

1. School of Aeronautics and Astronautics, Zhejiang University, Hangzhou 310027, China
• Received:2020-01-09 Revised:2020-03-02 Published:2020-02-27
• Supported by:
DRAGY (690623)

Abstract: Micro-blowing technology can change the turbulent structure in a flat plate flow and reduce the wall friction drag. In this paper, two cases of inflow through a smooth plate and a NASA-PN2 porous plate at Mach number 0.7 are respectively resolved by direct numerical simulation. Comparison of the flow characteristics in the two cases proves the effectiveness of micro-blowing technology on drag reduction, with the maximum rate reaching 45%. Furthermore, because of the "memory" function controlled by micro-blowing, the effect will last for a certain distance in the downstream, thus expanding the area of drag reduction. The explanation for the drag reduction in a wall turbulent boundary layer is the production of a low-speed "turbulence spot" in the near-wall region, which increases the thickness of viscous sub-layer and uplifts the average velocity profile. However, the turbulent velocity fluctuations in the boundary layer are strengthened simultaneously. Further analysis of the evolution of stream-wise vortex fluctuations reveals that micro-blowing plays multiple roles. It not only enhances the intensity of stream-wise vortex fluctuations, but also uplifts the stream-wise vortex clusters away from the wall, hence directly reducing the interaction between the stream-wise vortex and the wall surface. In addition, the impact caused by micro-blowing will leave dents on the vortex surface, leading to more dispersed and finely broken vortex clusters.