| There are abundant water resources in china.The present and future development of hydropower projects will be mianly concentrated in the southwest,where the topography of high mountains and canyons means that spillway tunnel is applied in many projects.Spillway tunnel could be constructed as the permanent building,or be transformed from the temporary engineering diversion tunnel.One tunnel could be used as two purposes,which is an economic approach and being appiied to many projects.These flood discharge tunnel have some common hydraulic characteristics: high water head,free surface,ogee section,ski-jump energy dissipation etc.in-deepth research in these questions is very necessary in engineering.Based on the previous research,the main contents of this paper are as follows:(1)Through consulting documents,the article summarizes the research status of high water head discharge tunnel with free surface,the main problems are energy dissipation,aeration and flow optimization.Energy dissipation of ski-jump type is the most commonly used type,now there are many kinds of flip bucket types for engineering to choose.aeration is the main measures to reduce cavitation in the project,researchers have proposed various aeration facilities.In order to optimize the spillway flow,the shape of discharge tunnel is always designed to be streamline.The three-dimensional numerical simulation method of the spillwaytunnel is becoming more and more commom.(2)Some basic theory of numerical simulation for discharge flow is mentioned in this paper.Including the basic control equation of N-S equation,turbulence model especially two equation turbulence model being commonly applied to high reynolds number flow,multiphase flow model especially VOF model being used to capture the free surface and some methods to discrete control equation.(3)Based on a actual high water head spillway tunnel,its hydraulic characteristics are studied through model test.Flow rate,deepth of water,velocity,pressure and the Scour topography are measured under various working conditions.And the effects of different aeration facilities are researched according to the test results,the discharge tunnel is also optimized.After optimization,the hydraulic characteristics are good.(4)Hydraulic characteristics of the tunnel are studied through numerical simulation.Meshing in ICEM software,computing in FLUENT software;using the RNG K-e turbulence model to simulate turbulence,using VOF method to track the free surface,the optimized model by model test is calculated.results are given such as discharge,water level,velocity and pressure.This paper analyzes the pressure characteristics of the bottom and side of the ogee segment and aeration segment,which is more concerned in the project.By comparing the numerical results with the experimental results,the conclusions of the two are consistent.Through studying the hydraulic characteristics of the discharge tunnel,the future similar projects get a reference;Comparison between the results of numerical simulation and model test results indicates that the numerical model is correct,which also provides a reference for future numerical simulation work. |
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