Study On Stiffness Characteristic Of Diaphragm Of 600MW Steam Turbines

As a significant component of a steam turbine to ensure the safety and economic efficiency, a diaphragm works mainly in two aspects:first, it could fix stationary blades; second, it is used to preventing the leakage of steam. Besides, the steam turbine is divided into several parts by diaphragms to make the enthalpy of each part be rational. The temperature and pressure of steam vapor become lower while steam vapor going through the stationary blades because of part of internal energy of vapor transferring into kinetic energy, and making the rotors rotating. With the tendency of larger capacity and higher parameters of steam turbine using in electric power industry, more and more attention was paid to the research about the characterize of diaphragm.In this paper, the stiffness characteristic of diaphragms was studied mainly using the ANSYS software. Basing on a real diaphragm designed by a certain steam turbine manufacture, several diaphragm models was built, and the distribution of pressure is discussed using Fluid-Solid-Interaction (FSI) method. The results indicate that the pressure on the surface of inlet and outlet is a nearly equal division. It is acceptable that the uniform force takes the place of CFD. The relationship between stress and the thickness of diaphragm is also concerned, and it is non-linear. The stress and deformation decrease slowly when it is thicker than a certain measure while the stress of blades may become larger because of the neutral axis change.The rationality of FEM in solving diaphragms’stress and stiffness is need to be demonstrated by diaphragm experiments. It is hardly executable to reappearing the real diaphragm work circumstance, point force has to be accepted to replace the distributed load. The work of the number of load points was also studied in this paper. The result demonstrates that at least six load points should be applied in diaphragm experiments. By simulating the stress and stiffness of diaphragms whose stationary blades has different height, a reasonable blade height should be chosen to make the measure more convenient.