Study on Hydraulic Characteristic of Submerged Jet with Depression Angle Dived into Plunge Pool from the Underwater Surface

Chuncai Zhang,Lijie Wang,Xiaobing Dai,D Zhang,B Zi,H Ding,G Cui

doi:10.1051/matecconf/20167706001

Abstract

Experiment research on submerged jet with depression angle dived into plunge pool from near-surface was carried out. The results showed that this type of energy dissipation type has good effect in improving the energy dissipation rate, reducing the surface fluctuation and reducing near-bed velocity and so on. Calculation formulas of conjugate depth and energy dissipation were obtained through theory analysis of submerged hydraulic jump in water cushion. Formula analysis showed that for high Froude number flow at a certain downstream depth, to obtain stable submerge hydraulic jump through adjusting size of jet exit, by decreasing its width is better way than by increasing height. When flow Froude number is larger sudden expansion ratio is more sensitive to energy dissipation, therefor to improving effect of energy dissipation by decreasing jet exit’s width or increasing plunge pool’s width can be used.

Highlights

In the last thirty years of reform and opening up, the country’s hydropower has made great achievements attracting worldwide attention
Traditional underflow energy dissipation cannot meet requirements of spillway with large unit power, near-bed flow velocity is high and bottom stability is poor in plunge pool [1, 2]; ski-jump energy dissipation of flood discharge has good effect, but atomization is difficult to avoid the impact on the environment [3,4,5,6]
Mid-South Design and Research Institute in conjunction Tuoba dam energy dissipation proposed submerged jet with depression angle dived into plunge pool from the underwater surface and conduct experimental studies [13], but this is a new type of energy dissipation type, water structure is complex and engineering practical experience is lack, so it is necessary to carry out in-depth research

Summary

Introduction

In the last thirty years of reform and opening up, the country’s hydropower has made great achievements attracting worldwide attention. Traditional underflow energy dissipation cannot meet requirements of spillway with large unit power, near-bed flow velocity is high and bottom stability is poor in plunge pool [1, 2]; ski-jump energy dissipation of flood discharge has good effect, but atomization is difficult to avoid the impact on the environment [3,4,5,6] For this reason, Sichuan University and Mid-South Design and Research Institute proposed horizontal submerged jets energy dissipation in setting the vertical drop and sudden enlargement of stilling pool and applied in Xiangjiaba hydropower project, and good results were achieved [7,8,9,10,11,12]. Findings enriched the study results of high-dam spillway energy dissipation and provided theoretical supports for engineering applications

Flow pattern of submerged jet with depression angle

Conjugate water depth

Energy dissipation ratio

Findings

Formulas analysis