The Experimental Study On The Downstream Local Scour And Hydraulic Characteristics Of Gate Dam Hydropower Station

The downstream local scour of the discharge sluice structure of low head, large flow hydropower station, is an important factor of the safety of hydropower station. With the continuous growth of the gate dam construction, the study of the local scour of downstream rule becomes more and more urgent. Predict of the downstream local scour of the gate dam after completion. In order to accurately predict the shape and depth of the local scour, lay a foundation for the study on the scour problem and practical engineering applications.In order to accurately evaluate the downstream local scour of the discharge sluice structure of low head hydropower station, the scouring model test of four kinds of particle size and various flows was conducted, according to the sectional model of Juting hydropower station which was made based on considering the discharge sluice structure, flow characteristics, and river bed geological conditions downstream of hydropower station. Downstream movable bed test was done, and the flow velocity of the scour was collected used vectrino. Analysis of my results points to the conclusions:(1) Made the sectional model of Juting hydropower station, the scouring model test of four kinds of particle size and various flows was conducted, observation of the erosion process under different conditions, measure the velocity, depth, the distance form the deepest point to the end of sluice base under various conditions.(2) On the basis of the experimental results, the main factors affecting the local scour of gate dam hydropower station was analyzed, including unit discharge, water level difference between upstream and downstream of dam, river bed material size, and the depth formula of local scour and the distance formula form the deepest point to the end of sluice base were fitted out. In order to verify the applicability of the formula, the scour data of other 4 engineering was collected, and the results showed that the calculated results agreed well with the test results.(3) Based on the bed test, use vectrino to collect the velocity of 3 shapes of scour and 3 different flows, each condition collect 5sections. Calculate the mean velocity, turbulence intensity, shear stress, the turbulence kinetic energy of each condition, and analysis of the distribution of these hydraulic characteristics of various shapes of the scour.(4) The hydraulic characteristics show that, vertical mean velocity on the flow distribution of the scour pit is similar, the transverse and vertical with little change, longitudinal along the depth to increase gradually, reached the maximum value at the bottom. Each section of the turbulence intensity in the transverse has little change, the longitudinal and vertical along the water depth increases first and then decreases, when near bottom reaches maximum and then decreases rapidly. The turbulence intensity decreases gradually from the start along the floor of the gate of the end. The longitudinal Reynolds shear stress along the depth is increased first and then decreased, decreased gradually along the distribution. The overall trend of turbulent kinetic energy along the depth distribution is firstly increased and then decreased.