| During the operation of the turbine,the surface of the flow-passing component is often collided and hit by the sediment particles in the water flow,causing depressions and potholes on the surface of the guide vane and the runner,and even breaking in severe cases.Under the wear and tear of the hydraulic turbine,the damage of the surface of the overcurrent components becomes more and more serious.This can result in reduced unit efficiency and reduced operational safety and stability.The maintenance cycle was also affected,resulting in significant economic losses.At present,the design of the turbine is based on clear water,and its internal flow field characteristics are quite different from those under sand water conditions.For runners and moving guide vanes where the turbine’s sediment wear is particularly severe,small differences will result in very large differences in surface velocity of the components.As a result,the problem of sediment wear becomes more serious and difficult to predict.The Kizilsu River Basin in Xinjiang has been known for its many years of mud,and its sand has sharp edges and corners and a high hardness.The turbines built in it have been subjected to sediment erosion,especially the Xiate Hydropower Station with a rated head of up to 250 m,and the problem of sediment wear will be extremely serious.Therefore,it is very necessary to test the sediment wear of the power station.The main research results are as follows:1.According to the hydrological condition of Xiaite Hydropower Station,the true concentration of sediment,the particle size and working conditions,combined with the mechanism of hydraulic machinery sedimentation,the sediment abrasion test system of the turbine is proposed.2.Based on the simulation flow calculation results of the sand water flow field inside the full runner of the Schatt Power Station,the test plan for the sediment wear of the turbine guide vane is proposed.The flow line around the sand-water velocity field of the water-conducting mechanism is extracted as the flow boundary of the guide vane test,and the over-flow channel of the test section is designed accordingly.The motion-like similarity of the turbine guide vane flow test piece is used to make the test flow field of the guide vane closer to the real situation.3.Based on the simulation flow calculation results of the sand water flow field inside the full runner of the Schatt Power Station,the test plan for the sediment wear of the turbine runner blades is proposed.According to the calculation results,the estimated area where the turbine runner of the Xiate Power Station is the most abrasive.Convert the actual three-dimensional flow surface of this area into a two-dimensional flow surface.The single flow channel on the flow surface is used as a test flow channel to make the turbine runner blades close to the true flow distribution.The flow conditions are designed according to theguide vane opening and flow rate of the real machine working conditions to form a flow field similar to that in the real power turbine runner.4.The surface morphology of the runner blade and the guide vane before and after the test was tested by the 3D shaper.The depth curves of the runner blade and the vane surface before and after the wear were obtained,and the wear depth of each test point was obtained.The wear depth of the position measured by the runner and the guide vane is nonlinearly correlated with the sediment velocity at the corresponding position in the numerical simulation of the test section,and the wear distribution,wear rate and flow velocity and sediment of the runner and vane are obtained.The relationship between the concentrations.The fitting formula for the wear rate is obtained by fitting.The turbine runners and guide vanes to be selected for the Xiaite Hydropower Station in Xinjiang are estimated to be worn,and their wear and tear are obtained for many years.Provide reference for turbine design,runner and vane material selection and maintenance protection. |
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