Simulation Of Solid Particle Erosion Of Nuclear Power Steam Turbine

When the steam turbine is running,blades,valves and other equipment are often impacted by solid particles.Particles carried by air flow hit turbine blades after reaching a certain speed,resulting in the loss of blade surface materials.Particle erosion in most steam turbines occurs in the first few stages of high-parameter steam turbines,but engineering practice shows that similar problems exist in low-parameter steam turbines such as nuclear power plants.The inlet steam parameters of nuclear power steam turbine are saturated or slightly overheated.After doing work,the pressure and temperature parameters are further reduced to form wet steam,and condensed droplets adhere to the blade wall to form a liquid film.There are still many unknown problems about the impact of liquid film on the erosion of solid particles.In this paper,the erosion of solid particles in the condition of liquid film attached to the blades of low-parameter nuclear power steam turbine is studied:Firstly,from the erosion phenomenon of solid particles on steam turbine blades,the basic problem of impact of single particles on metal plane attached with liquid film under different conditions is extracted.By studying this problem,we can understand and master the numerical simulation method of solid particle erosion,and the quantitative influence of the existence and thickness of liquid film on particle impact energy,impact strength,damage caused by impact,impact rebound angle,etc.The quantitative relationship between tangential and normal rebound velocity,rebound angle of particles and stress and strain of metal plane under a certain liquid film thickness is obtained from the study of basic problems.When coupling turbine blades,it is found that the existence of wall liquid film can obviously change the motion state of particles,which will make the impact position of solid particles relatively concentrated,resulting in more serious erosion than that of dry wall.The maximum erosion amount of blade is 3.7E-10 kg/m~2when the blade wall is attached with 20 um liquid film,which is 58.6%different from that without liquid film,and the maximum erosion amount of static blade pressure surface with 25 um liquid film is 15.9%different from that without liquid film.Secondly,taking a five-stage nuclear power steam turbine as the research object,the steam flow in its cylinder was numerically simulated.On this basis,the quantitative relationship obtained by studying the metal plane attached with liquid film under different angles of single particle was introduced,and the erosion of solid particles in multi-stage steam turbine was analyzed and simulated.The results show that the particles are obviously affected by centrifugal force during the movement,and the erosion of the blade group is the most serious in the area near the shroud.The erosion area of solid particles is dominated by the former three stages of moving and static blades,and the erosion degree of each stage of static blades is more serious than that of moving blades,with the erosion amount reaching 3.44E-10 kg/m~2in the most serious case,in which the erosion of the trailing edge on the back of static blades is mainly caused by the rebound of particles on the back of lower moving blades.