Research on Induced Vibration of Leakage Flow in Blade Tip Clearance of Steam Turbine

In order to reveal the law of the leakage flow of blade tip clearance inducing steamexcited vibration and further improve the safety of steam turbine operation, the numerical modeling method was used to analyze the mesoscopic characteristics of the flow field in the tip seal cavity, and the boundary vorticity flux was introduced into the flow field of tip seal to explore the relationship between the leakage vortices inside the uneven flow field and the steam-excited vibration force. The results showed that when the rotor ran eccentrically, the influence range of the vorticity in the seal cavity differed from vorticity intensity, leading to the distribution changes of boundary vorticity flux on the shroud surface, which further altered the tangential force on the shroud surface and induced the alternation of horizontal steam-induced excitation force. While the uneven flow field in the tip clearance changed the circumferential pressure difference on the shroud surface, which changed the radial steam-induced excitation force. When the rotors shared the same eccentricity, the different flow fields of the tip clearance maximized the horizontal steam-induced excitation force in the form of a flat-teeth seal, as well as the radial steam-induced excitation force in the form of a side-teeth seal. Installing the flat-teeth seal at the rotor tip is easier to increase rotor instability while installing the side-teeth seal can correct the eccentricity of the rotor to a certain extent. © 2022, Science Press. All right reserved.