| The distribution of water resource on spatial and temporal is seriously uneven in our country.With the rapid development of our country's economy and the rapid advancement of urbanization,the demand for fresh water in the different field is increasing,the problem of water shortage has become increasingly serious in the northwestern region,which has become a constraint to local economic and social development.In order to solve the problem of uneven water distribution in these regions,a large number of water delivery tunnels need to be built.The flow of the non-pressure branch tunnel is mainly affected by the upstream and downstream water level conditions and the gate opening degree,etc.The water level fluctuation during the water flow transition process is small,at the same time,it is convenient to the management and operation control,and the unfavorable hydraulic phenomenon has small appearance frequency,therefore,the non-pressure branch tunnel is widely used in the hydraulic tunnel.In the process of water filling,the flow state in the branch tunnel is a gas-liquid two-phase flow,and the hydraulic characteristics of the water flow in the branch tunnel varies with the shape of branch tunnel and the combination of different gate opening degrees.As a common water-dividing structure in branch tunnel,the diversion angles and shape have a great influence on the branch tunnel flow.The flow of the branch tunnel changes with the opening degree of the branch gate,and the gate opening is small,which may lead to unfavorable hydraulic phenomena such as alternating phenomenon of free flow and patially filled flow condition in the front of gate,affecting flow capability and safe operation of branch tunnel.Adjusting ability will decrease,if the gate opening is too large.In this paper,based on the central Shanxi Province long distance tunnel engineering,hydraulic phenomenon on intersection of the main tunnel,east branch tunnel and west branch tunnel,as the research object,by hydraulic model test and simulation calculation method,it is studied,which is flow regime,water line and aeration.Based on Fluent software,the water flow pattern in the branch tunnel in the water filling process is simulated,the standard turbulence model is adopted for numerical calculation,and the water and gas interface processing adopts the VOF method.In addition,some working conditions in the numerical calculation were verified by hydraulic model test,and the flow patterns and various hydraulic phenomena in the process of water filling in branch tunnel were observed by model test,and the monitoring section water depth and branch tunnel diversion ratio obtained by the two research methods were compared.The results show the discharge ratio of the branch tunnel under different diversion angles,the flow velocity and pressure on the outside of the inlet section of the side branch.The combination of gate opening degree under the design discharge ratio is given in the actual project water filling stage,and provides theoretical basis for engineering practice. |
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