Effect of blade tip pattern on blade load and vibration characteristics of a twin-stage axial flow fan

Focusing on a twin-stage axial fan, this paper investigates the effect of blade tip pattern on blade load and vibration characteristics. Steady simulations are first conducted to quantify the aerodynamic performance of various blade tip patterns. The finite element modeling analysis is performed to capture blade load and vibration characteristics, and Campbell diagram is introduced to evaluate resonance margin of different blade tip patterns. Results show that for all selected patterns, the first three mode shapes are mainly the bending of blade tip, which results in stress concentration at the blade root, while the last three are the waving in small range. The proposed blade tip patterns not only increase maximum stress and average deformation, but also significantly increase resonance margin near the rated speed. In addition, based on the harmonic response analysis, we find that the stress and amplitude frequency response will be notably altered by blade tip patterns.