Experimental Study of Turbulence Structure in Pulsatile Pipe Flow

脉动管流湍流结构的实验研究

基本信息

批准号：
62550131
负责人：
IGUCHI Manabu
金额：
$ 1.22万
依托单位：
Osaka 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：
1987
资助国家：
日本
起止时间：
1987 至 1988
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-62550131/
关键词：
Unsteady Flow Pulsatile Pipe Flow Propagation of Turbulence Ordered Motions Reynolds Shear Stress Relaminarization Transient Flow 乱流スラグうず動粘性係数バースト周波数

项目摘要

1. A couditional sampling technic based on four quadrant classification was used to clarify the turbulence structure in pulsatile pipe flows. The pulsation frequency was chosen to be about one tenth of mean burst frequency. Turbulence was generated near the wall by the same ordered motions as in a steady turbulent pipe flow. It propagated monotonically in the radial direction while decaying, but the decay rate was not affected by pulsation.2. A time lag t exists between the fundamental components of the cross-sectional mean velocity um and the root mean square value u'rms of the axial velocity component u'. The smallest value of t was designated by tg, and tnd the radial position at which t = tg was defined as the generation position of turbulence yg. yg was well approximated by yg 20.3. The radial propagation time of turbulence ( t- tg) was not affected by pulsation. Meanwhile, tg depended on pulsation and increased with increasing pulsation frequency. Both ( t- tg) and tg were dependent on the time-averaged Reynolds number Re ta. They decreased with increasing Re ta.4. Near the generation position ( t- tg) is well correlated by inner variables, u^^-_*,ta and .5. The measured values of ( t- tg) near the pipe center were well correlated by u^^-_*,ta and pipe radius R.6. Two empirical equations for ( t- tg) were proposed.7. Models for the Reynolds shear stress and eddy visocosity in pulsatile pipe flow were proposed.8. Standing wave appeared when f was increased up to about 20 Hz, and relaminarization of flow occured under temporal as well as spatial accelerations. Turbulence structure in the relaminarizing process was investigated.9. The behavior of turbulent slugs in transient pipe flow was clarified.

1.采用基于四象限分类的循环采样技术来阐明脉动管流的湍流结构。脉动频率选择为平均突发频率的大约十分之一。通过与稳定湍流管流中相同的有序运动在壁附近产生湍流。衰减时沿径向单调传播，但衰减速率不受脉动影响。2．横截面平均速度um的基本分量和轴向速度分量u'的均方根值u'rms之间存在时间滞后t。将t的最小值设为tg，将t＝tg时的径向位置tnd定义为湍流yg的产生位置。 yg 与 yg 20.3 非常接近。湍流的径向传播时间（t-tg）不受脉动的影响。同时，tg 取决于脉动，并且随着脉动频率的增加而增加。 (t-tg) 和 tg 均取决于时间平均雷诺数 Re ta。它们随着 Re ta.4 的增加而减少。靠近生成位置 (t- tg) 与内部变量 u^^-_*,ta 和 .5 密切相关。管道中心附近的(t-tg)测量值与u^^-_*,ta和管道半径R.6有很好的相关性。提出了(t-tg)的两个经验方程。7．提出了脉动管流雷诺剪应力和涡粘性模型。 8．当 f 增加到约 20 Hz 时，出现驻波，并且在时间和空间加速度下发生流动的再层化。研究了再层化过程中的湍流结构。 9．澄清了瞬态管流中湍流段塞的行为。