Effects of temperature on drag reduction in a subsonic turbulent boundary layer via micro-blowing array  

作　　者：Lan XIE Binghua LI Yang ZHANG Yao ZHENG Jianfeng ZOU 

机构地区：[1]Center for Engineering and Scientific Computation,and School of Aeronautics and Astronautics,Zhejiang University,Hangzhou 310027,China

出　　处：《Chinese Journal of Aeronautics》2022年第9期174-193,共20页中国航空学报（英文版）

基　　金：supported by the European-China Joint Projects‘Drag Reduction via Turbulent Boundary Layer Flow Control(DRAGY)’(No.690623);The National Supercomputing Center in Guangzhou provides the computing resources for the simulations in this paper。

摘　　要：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 microblowing 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 lowfrequency patterns just maintain but are lifted up.

关 键 词：Drag reduction Dynamic mode decomposition Micro-blowing Turbulent boundary layer Vortex 

分 类 号：V211[航空宇航科学与技术—航空宇航推进理论与工程]