Study on the Relaminarization of Transitional and Turbulent Boundary Layers

过渡边界层和湍流边界层的再层化研究

• 批准号: 13650963
• 负责人: ASAI Masahito
• 金额: $ 2.3万
• 依托单位: Tokyo Metropolitan Institute of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2003
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13650963/
• 关键词: Boundary Layer; Laminar-Turbulent Transition; Flow Instability; Vortices; Low-Speed Streaks; Suction; 境界層吸い込み

First examined are disturbance developments in the relaminarization and retransition process of boundary layer. Boundary layer suction is locally applied through a short perforated wall strip to a turbulent boundary layer to examine the development of near-wall low-speed streaks in the retransition region downstream of the suction strip. Low-frequency velocity fluctuations, which are markedly suppressed near the wall by the suction, start to grow algebraically downstream of the suction strip, leading to the retransition to wall turbulence. The algebraic growth of near-wall low-frequency fluctuations corresponds to the development of low-speed streaks and is caused by survived but decaying turbulent vortices through lift-up mechanism due to the associated streamwise vorticity component. The spanwise spacing of the newly developed low-speed streaks is fund to be almost the same as that in the turbulent boundary layer in the absence of suction even in the early stage of the streak develop … More ment. Immediately after the saturation of streak development, the secondary instability and eventual breakdown of low-speed streaks occurs being accompanied by wall burst. As the streak breakdown proceeds, the log-law region starts to appear in the mean velocity profile.Second the streak instability is examined experimentally by artificially generating spanwise-periodic low-speed streaks in a laminar boundary layer on a flat plate. Fundamental and subharmonic modes are excited for each of the sinuous and varicose instabilities. The development of subharmonic sinuous mode does not strongly depend on the streak spacing and it grows with almost the same growth rate as that for the single streak. By contrast, the development of fundamental sinuous mode is very sensitive to the streak spacing and is completely suppressed when the streak spacing is smaller than a critical value, about 2.5 times the streak width for the low-speed streaks examined. On the varicose instability, the fundamental mode is less amplified than the subharmonic mode, but the growth of both modes is weak compared with the case of the single streak Less

首先考察了边界层再区域化和再转折过程中的扰动发展。边界层吸力通过一个短的穿孔壁条局部作用于湍流边界层，以研究在吸力带下游的再转换区中近壁低速条纹的发展。在壁面附近被吸力显著抑制的低频速度脉动开始在吸力带下游代数地增长，导致重新转变为壁面湍流。近壁低频脉动的代数增长对应于低速条纹的发展，是由于相关的流向涡量分量的抬升机制而造成的幸存但衰减的湍流涡旋。即使在条纹发展的早期阶段，新发展的低速条纹的展向间距也与湍流边界层中的间距几乎相同，即使在条纹发展的早期阶段…也是如此更多的痛苦。在条纹发展饱和后，低速条纹立即发生二次失稳并最终破裂，并伴随着壁面破裂。其次，通过在平板层流边界层中人为地产生跨周期低速条纹，对条纹不稳定性进行了实验研究。对于每一种弯曲不稳定性和曲张不稳定性，都会激发基模和亚谐模式。亚谐正弦模式的发展不强烈地依赖于条纹间距，它的生长速度与单条的生长速度几乎相同。相比之下，基本正弦模式的发展对条纹间距非常敏感，当条纹间距小于临界值时，基本正弦模式的发展被完全抑制，临界值约为所考察的低速条纹条纹宽度的2.5倍。在曲张不稳定性方面，基模的放大比亚谐模式小，但两个模的增长都弱于单条纹少的情况

项目成果

日野幹雄: "スペクトル解析ハンドブック"朝倉書店. 723 (2004)

日野干雄：《频谱分析手册》朝仓书店 723 (2004)。

Konishi, Y., Asai, M.: "Experimental investigation of the instability of spanwise-periodic low-speed streaks"Fluid Dynamics Research. (in press). (2004)

小西，Y.，浅井，M.：“翼展周期低速条纹不稳定性的实验研究”流体动力学研究。

Asai, M., Tabei, K., Konishi, Y.: "Development of the streaky structure in a boundary layer disturbed by turbulent fluctuations"Proc.Int.Symposium on Dynamics and Statistics of Coherent Structures in Turbulence : Roles of Elementary Vortices. 25-36 (2002)

Asai, M.、Tabei, K.、Konishi, Y.：“受湍流涨落干扰的边界层中条纹结构的发展”Proc.Int.湍流相干结构动力学和统计研讨会：基本涡旋的作用。

Masahito Asai: Proceedings of International Symposium on Dynamics and Statistics of Coherent Structures in Turbulence : Roles of Elementary Vortices. 25-36 (2002)

Masahito Asai：湍流相干结构动力学和统计国际研讨会论文集：基本涡旋的作用。

浅井 雅人: "乱流変動を伴う境界層における壁近傍ストリーク構造の発生と成長"航空宇宙技術研究所特別資料. (印刷中). (2002)

浅井正人：“湍流波动边界层中近壁条纹结构的生成和生长”航空航天技术研究所的特殊材料（2002 年）。