Studies on By-Pass Transition of Boundary Layr

边界层旁路转变研究

• 批准号: 08651090
• 负责人: ASAI Masahito
• 金额: $ 1.41万
• 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: 1996
• 资助国家: 日本
• 起止时间: 1996 至 1997
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08651090/
• 关键词: Fluid Mechanics; Boundary Layr; Laminar-Turbulent Transition; Turbulent Contamination; Hairpin Eddies; Critical Reynolds Number; 乱流; 境界層

In the present study, the so-called by-pass boundary-layr transition caused by high-intensity disturbances is examined experimentally. Our knowledge of the boundary-layr response to such high-intensity disturbances is crucial, for instance, for understanding the attachment-line contamination on a swept wing. In addition, it is expected that the results give much information on the mechanism of wall turbulence generation and the related critical flow condition.The whole experiment is carried out in a wind tunnel with open jet type. A boundary-layr plate is set in the open test section. Well-controlled hairpin eddies is introduced in Blasius boundary layr at subcritical Reynolds numbers (for linear instability) through a small wall orifice. The results obtained are summarized below.Local turbulent patch created by the orifice-generated hairpin vortices can develop only at Reynolds numbers above R_<rheta>=130 (based on the momentum thickness). In such low-Reynolds number transition, the l … More ateral growth of turbulent patch is very weak, i.e., the lateral spreading angle is less than 2 deg. With increasing the Reynolds number, the lateral spreading angle is rapidly increased towards the typical value (10 deg) at high Reynolds numbers. The dependency of the lateral spreading angle of turbulent patch on R_<rheta> is clearly demonstrated in the present experiment. It is also worth noting that the growth of turbulent patch is highly dependent on the intensity of initial hairpin vortices in this subcritical boundary-layr transition.A key event observed is found to be successive growth of wall shear layrs (lifted up on low-speed streaks) with streamwise vortices into hairpin vortices, which is almost the same as the near-wall phenomena observed in the late stage of the ribbon-induced transition in plane Poiseille flow. Below the critical station (R_<rheta>=130), even if highly disturbed and once the wall streaks with streamwise vortices are created, they eventually decay downstream. Less

在本研究中，通过实验检查了由高强度疾病引起的所谓旁路边界 - 落地跃迁。例如，我们对这种高强度疾病的边界 - 莱尔响应的了解至关重要，例如，对于理解扫荡机翼上的依恋线污染。此外，预计结果可以提供有关壁湍流产生机理和相关临界流条件的大量信息。整个实验是在具有开放式射流类型的风洞中进行的。在开放测试部分中设置了边界 - 莱尔板。在Blasius Boundary Layr中引入了良好控制的发夹涡流，该层在亚临界雷诺数（对于线性不稳定性）中，通过小壁孔。在下面总结了所获得的结果。孔口生成的发夹涡流创建的局部湍流贴片只能在r_ <hreTa> = 130的雷诺数上发展（基于动量厚度）。在这样的低雷诺数过渡中，l…湍流斑块的更偏见的生长非常弱，即横向扩散角度小于2度。随着雷诺数的增加，在较高的雷诺数下，横向扩散角迅速增加朝着典型值（10 deg）。在本实验中清楚地证明了湍流贴片对R_ <hreta>的横向扩散角的依赖性。还值得注意的是，湍流斑块的生长高度取决于在此亚临界边界 - 边界 - 荷兰过渡中的初始发夹涡流的强度。发现观察到的关键事件是墙面剪切层的成功增长（在低速条纹上升起），随着近乎相同的旋转，在近期旋转中，在接近旋转中的旋转 - 在现象中的阶段 - 在现象中的阶段，是在现象中的阶段 - 流动。即使在高度干扰的情况下，一旦创建了流向涡流的壁条，它们最终在下游衰减。较少的

项目成果

Masahito Asai: "Three-dimensional growth of Tollmien-Schlichting waves excited at two frequencies." Fluid Dynamics Research. 22-4. 215-230 (1998)

Masahito Asai：“在两个频率下激发的 Tollmien-Schlichting 波的三维增长。”

M.Asai: "Development of Wall Turbulence Structure in Transitional Flows" Theoretical and Applied Mechanics 1996,Elsevier. 121-138 (1997)

M.Asai：“过渡流中壁湍流结构的发展”理论与应用力学1996，爱思唯尔。

Masahito Asai: "Lateral Turbulent Contamination in Subcritical Boundary-Layer Transition" Memoirs of Tokyo Metropolitan Institute of Technology. 10. 109-115 (1996)

Masahito Asai：《亚临界边界层转变中的横向湍流污染》东京都工业大学回忆录。

M.Asai: "Development of Wall Turbulence Structure in Transitional Flows" ICTAM Kyoto 1996, Elsevier. (1997)

M.Asai：“过渡流中壁湍流结构的发展”ICTAM 京都 1996 年，爱思唯尔。

Masahito Asai: "Development of wall turbulence structure in transitional flows." Theoretical and Applied Mechanics (eds.T.Tatsumi, E.Watanabe & T.Kambe), Elsevier. 121-138 (1997)

Masahito Asai：“过渡流中壁面湍流结构的发展。”