Experimental Study And Numerical Simulation On Energy Dissipation And Erosion Control Of Lianhuatai Hydropower Station

Energy dissipation and erosion control is one of the key technical problems of the water conservancy and hydropower project field. Along with a lot of hydropower projects has been completed in succession, the rest projects whether high dam or low one, most of them have the characteristic of large discharge, large unit width discharge, shallow downstream water cushion and poor geological conditions of riverbed, so the energy dissipation and erosion control problem is very prominent. The Dan river Lianhuatai Hydropower Station is one of typical Riverbed-hydroelectric Stations with middle head. This station has the peculiarities so you say, its river regime is bending in dam site and the hydropower station tailrace is close to the discharge structure, so solving those problems and getting better water flow regime will be very important for hydro-junction layout, project scale, safe operation, exerting the benefit and so on. The research work is carried out in this background and the concrete study object is energy dissipation and erosion control problem of Lianhuatai power station. The main contents of the studies and achievements are as followed:(1) Building the unitary normal model which the scale is 1:80.A systematic energy dissipation and erosion control research of the sluice dissipator was been made. Then the main problems of preliminary design such as the sluice layout, discharge capacity, water flow regime and riverbed scouring were given. Through several tests and shape optimization, the recommended scheme(Y-shape flaring gate pier and bucket typed stilling pool combined energy dissipator) was presented. The schemes successfully solved those problems in the preliminary design. The last gate operation way was improved.(2) By k-εdouble equations turbulence model and VOF(Volume Of Fluid)method,it was successful to carry out three-dimensional numerical simulation on the field of turbulent flow of preliminary design and recommended scheme, and then the flow field, water surface profile, pressure and velocity distribution, and other related hydraulic parameters were gotten. By comparison, the simulated results were in good agreement with test data.(3) Simulating the flow field of the normal tailless pier energy dissipater, and then comparative analysis is carried out on pressure distribution of recommended scheme simulated results and test data. The results show that the pressure of all WES model overflow dam of combined energy dissipator is positive pressure and its force reduction pool bottom pressure distribution is higher than the normal one. Those are help for dam surface safety and force reduction pool bottom stability.(4)Discussing the topic negative pressure question founded in numerical simulation and analyzing the reason of bringing negative pressure condition. Using Theoretical Mechanics theories, the negative pressure condition generation mechanisms on ogee section were analyzed. Then flow cavitation number of overflow dam was calculated.(5) From the view of the hydraulic characteristics, the hydraulic calculation of deflecting flow was carried out. And by the viewpoint of local energy loss, the ratio of energy dissipation of flaring gate pier combined energy dissipator was analyzed. The notes of hydraulic calculation, Model test and numerical simulation for deflecting flow were pointed out. The Causes of the good and stable effect of energy dissipation were analyzed; also the calculation and analysis of hydraulic jump characteristics were carried out. The results show that the flaring gate pier and bucket typed stilling pool combined energy dissipator has obvious advantages for solving Energy dissipation and erosion control problems with large unit width discharge and low Fr current.The research in this thesis successfully resolved the energy dissipation and erosion control practical problem of Lianhuatai Hydropower Station,and thoroughly studied the hydraulic characteristics of flaring gate pier and bucket typed stilling pool combined energy dissipator. The accomplishment of this study will be of theoretical and practical significance for similar project.