Study On Diaphragm’s Stiffness Characteristic Of Large Capacity Steam Turbines

The steam turbine diaphragm is one of the critical components to ensure the safety and economical efficiency of turbines. It plays an role in fixing stationary blades and preventing the leakage of steam. And it separates the total enthalpy drop of the turbine into several sections. In this way, internal energy of the high-temperature and high-pressure vapor can be transformed into kinetic energy, which is converted further into mechanical energy by rotating the impeller. With the tendency of developing the advanced parameter and large capacity turbogenerator unit in the electric power industry, research in the stiffness characteristic has been paid more and more attention.In this paper, research in the stiffness characteristic of diaphragms is carried on mainly through numerical simulation methods. One real diaphragm model from a certain turbine manufacturer is chosen as the research object. Its boundary conditions are analyzed in detail. The contact FEM is used to deal with diaphragm’s supporting problems in the software of ANSYS. Compared with regarding the supporting boundary as perfectly rigidity, the results indicate that the contact FEM is more precise and more reliable. And this method is not so difficult for engineers to apply in ANSYS.In order to demonstrate the reasonableness of contact FEM in dealing with diaphragm’s supporting problems, it’s necessary to carry out experiments in the future. Therefore, influence of different number of loading points on the diaphragm’s deflection is discussed in this paper, and the simulated results indicates it is obvious. With the increase of loading points, the situation is closer to the case of uniformly distributed load. Considering present experimental conditions in the laboratory, the experiment will be carried out in the manner of a single loading point. Of course, its result can’t reflect the real deformation of the diaphragm. However, the level of closeness between simulated results under different boundary conditions and the experimental result can be obtained. It can be used to estimate the reasonableness of different boundary conditions. This will provide some certain guidance for the experiment in the future.