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Study on Goertler and T-S Type Instability of Boundary Layr Flow on Rotating Curved Wall

旋转曲壁边界层流Goertler和T-S型不稳定性研究

基本信息

批准号：
09450075
负责人：
HASEGAWA Yutaka
金额：
$ 9.41万
依托单位：
Nagoya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

项目摘要

Stability of laminar boundary layer having a mean velocity of Blasius type was studied by solving numerically the perturbation equations when the boundary layer is subject to the centrifugal force due to the streamline curvature and the Coriolis force due to the system rotation and the following results have obtained theoretically.(1) When the Coriolis force acts toward the concave surface, the boundary layer is more unstable and vortices are generated at a lower value of wall curvature. With larger Coriolis force, Goetler vortices would appear even on a convex surface.(2) In a lamianr boundary layer with an adverse pressure gradient occurrence of the Goertler vortices are promoted by the Coriolis force acting toward the wall surface.In order to verify the calculation results, a curved channel whose radius of curvature and aspect ratio of the channel section are equal to 1000mm and 8, respectively, was made and mounted on a rotating table of 3000mm diameter. Air was introduced through an two-dimensional nozzle and exhaused azially theou the axis. The natue of the boundary layer on a convex and concave surfaces were ezmained on a thin durved plate inserted along the centerline of the channel using a hot wire probe.Experiments were carried out in a stationary state of the channel at the Reynolds numbers of Re = 40,000 and 80,000. The following results were obtained.The centrifugal force causes a large effect on the development of the boundary layer and accelerate the transition to the turbuent state in the concave side but the force suppresses the turbulent motion in the boundary layer on the convex side and deleys the transition to the turbulent state.

本文通过数值求解扰动方程，研究了具有Blasius型平均速度的层流边界层在流线曲率离心力和系统旋转科里奥利力作用下的稳定性，并从理论上得到了下列结果。(1)当科里奥利力作用于凹面时，边界层更不稳定，在较低的壁面曲率值处产生旋涡。当哥氏力较大时，即使在凸表面上也会出现Goetler涡。(2)在有逆压梯度的层流边界层中，哥氏涡的产生是由于哥氏力作用于壁面而引起的.为了验证计算结果，在直径为3000mm的旋转工作台上制作了曲率半径为1000mm，通道截面长宽比为8的弯曲通道.空气通过二维喷嘴引入，并沿轴向流动。在雷诺数Re = 40，000和80，000的定常状态下，用热线探针在沿通道中心线沿着插入的薄平板上测量了凸、凹表面上的边界层性质。结果表明：离心力对凹侧边界层的发展有较大影响，加速了凹侧边界层向湍流状态的转变，而对凸侧边界层的湍流运动有抑制作用，延缓了凸侧边界层向湍流状态的转变。