Research on the blade tip vibration characteristics of boiler circulating pump induced by tip leakage vortex

Abstract

Boiler circulation pumps serve as the critical component in the water circulation systems of power plant boilers. Owing to elevated temperature and high-flow-rate operating conditions, the internal flow is typically axial in configuration. Under such conditions, tip leakage flow becomes inevitable, often leading to adverse effects including pump vibration and blade fatigue. This study employs Delayed Detached Eddy Simulation (DDES) turbulence model combined with bidirectional fluid-structure interaction (FSI) approach to numerically investigate the flow within the tip clearance region. The results indicate that the evolution of the tip leakage vortex can be categorized into four distinct evolutionary phases: initiation, shedding, dissipation, and subsequent reformation. Among these, the dissipation and reformation stages are identified as the primary contributors to stress concentration and vibratory excitation along the mid-chord region of the blade. Furthermore, the frequency of the tip leakage vortex intensity fluctuations correlates closely with the vibrational frequency measured at monitored points on the blade. The influence of the tip leakage vortex is most pronounced near the blade’s leading edge and mid-chord area. Under design conditions, the localized peak fluid force induced by the interaction between the tip leakage vortex and the blade surface can reach magnitudes as high as 255 MPa.