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Effects of Coriolis force on coherent structure of wall turbulence

科里奥利力对壁面湍流相干结构的影响

基本信息

批准号：
02650132
负责人：
KITOH Osami
金额：
$ 1.02万
依托单位：
Nagoya Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1990
资助国家：
日本
起止时间：
1990 至 1991
项目状态：
已结题

项目摘要

Mean velocity profiles in a rotating channel are governed by three parameters ; Re^*=u^*D/nu , OMEGAnu/u^<*2> and OMEGAD/u^* where u^*, D and OMEGA are friction velocity, channel half height and angular velocity respectively. A flow regime space suggested in this research is shown to be very convenient to understand the over all effects of Coriolis force and the Reynolds numbers. The wall law is affected by the Coriolis force effect. The effects are expressed as the Van-Driest, Karmann and integral constants being functions of OMEGAnu/u^<*2> instead of being universal constants. The Coriolis region where flows are affected only by the Coriolis force is shown to exist and the velocity law is developed.The Reynolds stress uv at a pressure side increases as a result of increase of contribution from ejection process. At a suction side, the situations are reversed. The contributions to us from sweep and interaction processes do not show much change in a rotating channel. However, when relaminarisation occur at suction side, both sweep and ejection processes weaken and uv<similar or equal>0. The correlation coefficient between u and v increases/decreases at pressure/suction side which shows the turbulent structure change to occur in a rotating channel. The power spectrum of v velocity component reduces appreciably in a low wave number range in a suction side. There appears a knee point at wave number=0.3 in a spectrum distribution of v measured at y+=80 when the rotation Reynolds number (2D)^2OMEGA/nu =<plus-minus>140. This discontinuity is caused by the turbulent motion having the time scle of pi/OMEGA ; half time period of channel rotation. The VITA technique to detect the burst can not well be applied to this flow.

旋转通道中的平均速度分布由三个参数决定：Re^*=u^*D/nu、Ω Anu/u^<*2>和Ω GAD/u^*，其中u^*、D和Ω分别是摩擦速度、通道半高和角速度。本文所提出的流型空间，对于全面了解哥氏力及雷诺数的影响，是非常方便的。壁面定律受科里奥利力效应的影响。这些效应表示为范-德里斯特、卡门和积分常数，它们是Ω Anu/u^<*2>的函数，而不是普适常数。结果表明，存在只受科里奥利力影响的科里奥利区，并给出了速度定律，压力侧雷诺应力uv由于喷射过程的贡献增大而增大。在吸入侧，情况相反。在旋转通道中，扫描和相互作用过程对我们的贡献并没有太大的变化。然而，当再层化发生在吸力面，扫描和喷射过程减弱和uv <similar or equal>0。u与v的相关系数在压力/吸力侧增大/减小，表明旋转通道中湍流结构发生了变化。吸力面速度分量的功率谱在低波数范围内明显减小。当旋转雷诺数（2D）^2 Ω/nu = 140时，在y+=80处测得的v的谱分布中，在波数=0.3处出现拐点<plus-minus>。这种不连续性是由具有π/Ω时间尺度的湍流运动引起的;通道旋转的半时间周期。VITA法检测突发流不能很好地应用于这类流。