Turbidity Current in a Settling Tank

沉淀池中的浊流

• 批准号: 01550497
• 负责人: FUJISAKI Kazuhiro
• 金额: $ 1.02万
• 依托单位: Kyushu 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: 1989
• 资助国家: 日本
• 起止时间: 1989 至 1990
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-01550497/
• 关键词: Turbidity current; Settling tank; Settling of suspension; Sediment-laden flow

This paper describes the turbidity current in rectangular settling tank. When sediment-laden water flows into settling tank, it flows downstream as the water is heavier than the ambient one. When the turbidity current developed to the large extent, it resuspends or picks up settled particles from tank bottom into the bulk flow and the bead water zone may be produced at the water surface. These phenomena decreases in the efficiency of the settling tank. The objective of this work is make clear the basic properties of this kind of density current.The laboratory experiment are conducted in a model settling tank, which has 0.2m width, 5m length and 1.5m depth. Flow velocity profiles and sediment concentration distributions in a tank are measured under various flow conditions.In the theoretical analysis, the mass conservation for both fluid and sediment, and equation of motion of fluid were employed. To the treatment of the density difference, the Businesque approximation is used and the turbulent diffusivity is assumed to be constant through the tank. Under these assumptions, the turbidity current can be expressed by only two parameters, Fdc : The densimetric Froude number and K : nondimensional kinematic turbulent diffusibility.After confirming that the numerical solution of the theoretical equation can predict the experimental results, the turbidity current are discussed by using the theoretical model. The maximum velocity of turbidity current Um are given as a function of both Fdc and k, and critical values from which the dead water zone appears are presented. These results show that the turbidity current develops with decrease in the value of Fdc and K. For practical use, an approximate simple equation is given which gives the relationship between Um, Fdc and K.As an additional work on this topic, some other work, such as horizontal pipe line flow with suspended sediment and the turbidity current induced by sediment disposal are also presented.

本文描述了矩形沉淀池中的浊流。当含沙水流进入沉淀池时，由于水体比周围水体重，含沙水流向下游流动。当浊流发展到很大程度时，它会重新悬浮或将池底沉降的颗粒带入主流中，并可能在水面产生珠水区。这些现象降低了沉降槽的效率。本文在宽0.2m、长5m、深1.5m的模型沉淀池中进行了异重流的实验研究，旨在弄清异重流的基本特性。在不同的水流条件下，测量了水槽内的流速分布和含沙量分布，在理论分析中，采用了流体和泥沙的质量守恒和流体运动方程。对于密度差的处理，采用了厄格斯克近似，并假定湍流扩散系数为常数。在此假设下，浊流可以用密度弗劳德数（Fdc）和无量纲运动学湍流扩散系数（K）两个参数来表示，在证实理论方程的数值解可以预测实验结果后，利用理论模型对浊流进行了讨论。给出了浊流最大流速Um与Fdc和k的函数关系，并给出了出现死水区的临界值。结果表明，随着Fdc和K值的减小，浊流发展。为了实际应用，给出了一个近似的简单方程，它给出了Um，Fdc和K之间的关系。作为本课题的补充工作，还介绍了其他一些工作，如水平管道悬浮泥沙流和泥沙排放引起的浊流。

项目成果

Kazuhiro Fujisaki,Toshitaka Ono and Yoichi Awaya: "Studies on the turbidity current in settilng tank" Proceedings of the International Conference on Water and Wastewater,Beijing,CHINA. 51-56 (1989)

Kazuhiro Fujisaki、Toshitaka Ono 和 Yoichi Awaya：“沉淀池浊流研究”国际水与废水会议论文集，北京，中国。

藤崎 一裕,林 秀樹,吉武 範幸,粟谷 陽一: "開水路流れにおける縦分散に及ぼす密度勾配の影響" 土木学会第45回年次学術講演会講演概要集. 448-449 (1990)

Kazuhiro Fujisaki、Hideki Hayashi、Noriyuki Yoshitake、Yoichi Awaya：“密度梯度对明渠流纵向分散的影响”日本土木工程师学会第 45 届年度学术会议摘要 448-449（1990 年）。

Kazuhiro Fujisaki, Hideki Hayashi, Noriyuki Yositake and Yoichi Awaya: "Effect of density gradient on longitudinal dispersion in open-channel flow" Proc. of 45th Annual Meeting of JSCE. 448-449 (1990)

Kazuhiro Fujisaki、Hideki Hayashi、Noriyuki Yositake 和 Yoichi Awaya：“密度梯度对明渠流纵向弥散的影响”Proc。

藤崎一裕,中山竜起,河野直樹,粟谷陽一: "水面より鉛直投入した沈降性粒子の挙動" 土木学会西部支部研究発表会講演概要集. 128-129 (1990)

Kazuhiro Fujisaki、Tatsuoki Nakayama、Naoki Kono、Yoichi Awaya：“从水面垂直注入的沉降颗粒的行为”日本土木工程师学会西部分会摘要 128-129 (1990)。

藤崎 一裕,林 秀樹,栗谷 陽一: "沈降性粒子を含む開水路流れにおける移流分散" 平成2年度 土木学会西部支部研究発表会講演概要集. 234-235 (1991)

Kazuhiro Fujisaki、Hideki Hayashi、Yoichi Kuritani：“含有沉积颗粒的明渠流中的平流和分散”1990 年日本土木工程师学会西部分会研究报告摘要 234-235 (1991)。