@article{XIE2022, 
author = {Lan XIE and Binghua LI and Yang ZHANG and Yao ZHENG and Jianfeng ZOU},
title = {Effects of temperature on drag reduction in a subsonic turbulent boundary layer via micro-blowing array},
year = {2022},
journal = {Chinese Journal of Aeronautics},
volume = {35},
number = {9},
pages = {174-193},
keywords = {Drag reduction, Dynamic mode decomposition, Micro-blowing, Turbulent boundary layer, Vortex},
url = {https://www.sciopen.com/article/10.1016/j.cja.2022.01.003},
doi = {10.1016/j.cja.2022.01.003},
abstract = {A comparative study of two micro-blowing temperature cases has been performed to investigate the characteristics of drag reduction in a subsonic flat-plate flow (where the freestream Mach number is 0.7) by means of Direct Numerical Simulation (DNS). With minute amount of blowing gas injected from a 32 × 32 array of micro-holes arranged in a staggered pattern, the porosity of micro-holes is 23% and the blowing coefficient is 0.125%. The simulation results show that a drag reduction is achieved by micro-blowing, and a lower wall-friction drag can be obtained at a higher blowing temperature. The role of micro-blowing is to redistribute the total kinetic energy in the boundary layer, and the proportion of stream-wise kinetic energy decreases, resulting in the thickened boundary layer. Increasing micro-blowing temperature can accelerate this process and obtain an enhanced drag reduction. Moreover, an explanation of drag reduction by micro-blowing related to the micro-jet vortex clusters is proposed that these micro-jet vortex clusters firmly attached to the wall constitute a stable barrier, which is to prevent the direct contact between the stream-wise vortex and the wall. By Dynamic Mode Decomposition (DMD) from temporal/spatial aspects, it is revealed that small structures in the near-wall region play vital role in the change of turbulent scales. The high-frequency patterns are clearly strengthened, and the low-frequency patterns just maintain but are lifted up.}
}