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.

在已有的对轴对称体周围分离现象的研究中，以下几点似乎很少被重视。一些结果表明，二维型分离似乎远离了三维开放式分离的开始。首先，油流型分离线与测量压力分布的平台边缘有较小的偏差。其次，迎风侧摩擦线与主离散线S_1.2不是相切而是垂直相交。测量结果表明，当Re=27000，α=40ﾟ时，峰值频率为19赫兹。这种频率可以归因于二维模式的旋涡脱落，例如圆柱体的理论脱落频率为15赫兹。尾部Reta=135时扰动的速度和频率较大，正流或倒流交替出现。横涡的摆动在阿尔法30ﾟ处约为1赫兹，而固定在模型表面上的阿尔法30ﾟ处，Re=8000.4。在一次和二次分离线之间的狭窄区域出现了较强的轴向反转，这与S_1和S_2之间拉长的时钟方向涡型的上部一致。

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。