摘要
纵向沟槽壁面的湍流边界层,当沟槽的脊-脊内尺度无量纲展向间距s^+在一定范围内,与光滑壁面湍流边界层相比,具有减阻效应;并在s^+约为17个黏性长度单位时减阻效果达到最优,之后其减阻趋弱,直至增阻;其原因可能是沟槽壁面湍流边界层由于"开尔文-亥姆霍兹"不稳定性而产生的一种"类开尔文-亥姆霍兹"展向涡结构.实验采用烟雾流动显示技术,首次在风洞中显示了这种"类开尔文-亥姆霍兹"展向涡结构,确认了其存在性,并在概念上简单勾勒了其结构模型.
Riblets perform a drag-reducing effect on the turbulent boundary layers(TBLs) in a certain range of their peak-to-peak spacings,s^+.However,the drag reduction produced by the riblets breaks down after s^+ increasing beyond its optimum value,and eventually the drag reduction becomes an increase case.Garcia-Mayoral and Jimenez(2011) believed that the breakdown is due to the onset of a Kelvin-Helmholtz instability in the TBL over riblets,which introduces a kind of Kelvin-Helmholtz-like roller structures.In the present study,these spanwise rollers,for the first time in experiments,were clearly observed by the smoke flow visualization technique.And their conceptual model was outlined lastly as well.
出处
《力学学报》
EI
CSCD
北大核心
2015年第3期529-533,共5页
Chinese Journal of Theoretical and Applied Mechanics
基金
国家自然科学基金(11272233
11332006
11411130150)
国家留学基金(201306250092)
天津大学优秀博士学位论文基金资助项目~~
