权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Studies on the Characteristics of the Flow at Abrupt Change of Bed Roughness

床面粗糙度突变时的流动特性研究

基本信息

批准号：
02660230
负责人：
KAWAGOSHI Nobukiyo
金额：
$ 1.28万
依托单位：
Hirosaki 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：
1990
资助国家：
日本
起止时间：
1990 至 1991
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-02660230/
关键词：
Flow with abrupt change of bed roughness Hydraulic jump Wave Large scale roughness Roughness bed Velocity profiles Internal boundary layer Aspect ratio 境界層の発達乱れ強度跳水現象護床工波状流

项目摘要

In this study, we investigate experimentally about three subjects, I. hydraulic jump and wave flow on large scale roughness(strip roughness and block roughness), 2. the growth of the internal boundary layer in the flow at abrupt change of bed roughness, 3. the effect of the channel width on the classical hydraulic jump.On 1. subject, the follows were obtained.(1)For a jump formed on large scale roughness, sequent depth, and the length of the surface roller of the jump is clearly reduced. The reduction in the relative length of the surface roller(Lr/h1)ranges from 30% to 40%. (2)The occurrence conditions and the characteristics of surface profiles for the wave flow on large scale-roughness agree almost with the wave flow at abrupt drops. (3)The decay of maximum velocity is more rapid, the growth of the boundary layer thickness is faster when compared with the corresponding smooth bed jump.On 2. subject, (1)the velocity and turbulent intensity profiles of flow downstren of abrupt change from smooth bed to rough beds which are composed of glass beds were discussed. (2)The internal boundary layer thickness can be derived from the turbulent intensity profiles. (3)The development of the internal boundary layer(delta)may be given as delta = a・X^b, (b<similar or equal>0.7).On 3. subject, the influence of scale effect and aspect ratio for hydraulic jump is discussed from sequent depth, water surface fluctuations, energy loss in the jump, and velocity distributions at the end of the jump.

本文主要研究了大尺度粗糙度（条状粗糙度和块状粗糙度）下的水跃和波浪流；在床层粗糙度突变时流动中内边界层的生长；水道宽度对经典水跃的影响。在1。结果如下：(1)对于大尺度上形成的跳变粗糙度、顺序深度，以及跳变辊表面的长度都明显减小。表面辊的相对长度（Lr/h1）的减小幅度在30% ~ 40%之间。(2)大尺度粗糙波流的发生条件和表面剖面特征与陡坡波流基本一致。(3)与相应的平滑层跃相比，最大速度衰减更快，边界层厚度增长更快。在2。主题：(1)讨论了由光滑床层到粗糙床层的玻璃床层突变的下游流速和湍流强度分布。(2)内边界层厚度可由湍流强度曲线推导。(3)内边界层（三角洲）的发育可表示为delta = a·X^b, （b<相似或等于>0.7）。在3。本文主要从连续深度、水面波动、跳跃过程中的能量损失以及跳跃结束时的速度分布等方面讨论了尺度效应和纵横比对水力跳跃的影响。