Dynamic stress characteristics and fatigue life analysis of a slanted axial-flow pump

Abstract

The shaft of the slanted axial-flow pump device is inclined, so, the stress on the impeller is complex, which leads to the prominent problem of structural reliability. In order to study the mechanical characteristics and fatigue life of the slanted axial-flow pump, the stress-strain characteristics and variation law of impeller under different flow rate conditions are analyzed by fluid-structure interaction method, at the same time, the stress-strain characteristics of impellers with geometrically similar and five different structural sizes when nD value is equal are solved, finally, the fatigue analysis of blades is carried out based on Miner’s linear fatigue cumulative damage theory to predict the fatigue life of impellers. The results show that under different flow rate conditions, the maximum equivalent stress of the impeller blade is concentrated at the blade root and gradually attenuates to the blade flange. The maximum deformation of the blade is located at the blade rim and moves from the inlet side to the outlet side with the increase of flow rate. When the nD value is constant, the maximum equivalent stress and maximum deformation displacement of the blade increase with the increase of the impeller size. Under various flow rate conditions, the service life of the impeller reaches 108, and the safety factor of each part of the blade is greater than 15, when operating within the working condition range of 0.8 Qbep∼1.2 Qbep, the impeller can operate continuously for 14 years without fatigue damage.