Fluctuation Distribution and Vortex Structure of in Three Dimensional Separated Flow

三维分离流脉动分布及涡结构

• 批准号: 03650049
• 负责人: NISHIKAWA Nobuhide
• 金额: $ 1.34万
• 依托单位: CHIBA-UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1991
• 资助国家: 日本
• 起止时间: 1991 至 1992
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-03650049/
• 关键词: Three Dimensional Separation; Boundary Layer; Lateral Vortex; Visualization; Turbulent Unsteady Flow; Visualization; 剥離流; 数値流体力学; 画像計測; 楕円柱; 可視化

The followings seem to be rarely emphasized in the existing studies for the separation phenomena around axisymmetric body.1. Some results clarify that the two-dimensional type separation appears away from the start of 3-D open separation. Firstly, the separation lines by oil flow pattern show small deviation from the edges of the plateau of measured pressure distribution. Secondly ,the skin friction lines at windward side intersect not tangentially but normally to the primary separation line S_1.2. The power spectra of the velocity as C.T.A measurement data show the peak frequency of 19 Hz for Re=27000,alpha=40ﾟ. The frequency can be attributable to vortex shedding in two- dimensional mode such as 15 Hz of theoretical shedding frequency for circular cylinder.3. The velocity and frequency of disturbance is large at rheta =135ﾟ at aft body where the positive flow or reversal alternatively appears. The swing of the lateral vortex exhbits the mode of 1 Hz or so at alpha>30ﾟ,while it is fixed on the model surface at alpha<30ﾟ,Re=8000.4. In the narrow region between the primary and secondary separation line the strong axial flow reversal appears,which consist with the upper part of the elongated and clock wise vortical pattern between S_1 and S_2.

现有的关于轴对称体分离现象的研究似乎很少强调以下几点： 1．一些结果表明，二维型分离是在远离三维开放分离开始的地方出现的。流型显示与测量压力分布的平台边缘有较小的偏差其次，迎风面的表面摩擦线与主分离线S_1.2不相切而是垂直相交。 C.T.A测量数据表明，Re=27000，α=40°时，峰值频率为19 Hz，该频率可归因于二维模式下的涡旋脱落，例如圆柱体的理论脱落频率为15 Hz。 3．尾部扰动频率较大，rheta=135ﾟ，正向流动或反向流动交替出现。在α>30ﾟ时表现出1 Hz左右的模态，而在α<30ﾟ时固定在模型表面上，Re=8000.4，在初级和次级分离线之间的狭窄区域出现强烈的轴流反转，它由 S_1 和 S_2 之间细长的顺时针旋涡图案的上部组成。

项目成果

Nishikawa,N, Ishide,T, and Kida,S.: "Surface Flow Patterns on Blunt Bodies" Proc.IUTAM Sympo.on Fluid Dynamics of High Angle of Attack(Springer Ver..as in Preprint. 32-33 (1992)

Nishikawa,N、Ishide,T 和 Kida,S.：“钝体上的表面流动模式”Proc.IUTAM Sympo.on Fluid Dynamics of High Angle of Attack（Springer Ver..as 预印本。32-33 (1992)）

A.Shaffi Nabil.,&N.Nishikawa: "Numerical analysis of Flows over walls with Protuberanse" J. of Wind Engineearing. 52. 418-423 (1992)

A.沙菲·纳比勒，

Nabil.A.Shafi,& N.Nishikawa, and H.Sudou: "Numerical Analysis of Laminar Flows over walls with Protuberance" Theoretical and Applied Mechanics. Vol.41. 213-222 (1992)

纳比尔·A·沙菲，

Nabil.A.Shafi,& N.Nishikawa: "Numerical analysis of Flows over walls with Protuberance" J. of Wind Engineering. No 52. 418-423 (1992)

纳比尔·A·沙菲，

N.NISHIKAWA and Toshio ABE: "Simulation and Graphics of Water-Enry Cavity in Cartesian Mesh" Theoretical and Applid Mechanics. 40. 279-286 (1991)

N.NISHIKAWA 和 Toshio ABE：“笛卡尔网格中吸水腔的模拟和图形”理论和应用力学。