Study on deformations of the two-stage impellers of contra-rotating fan driven by pole-changing motors

To meet the demand of different air distance, the pole-changing motors are used to drive the contra-rotating fan to realize speed matching. With the purpose of analyzing exactly the air pressure on the blades and deformations of the two-stage impellers when the contra-rotating fan runs at different speed ratios, a contra-rotating fan as FBD5.0/2 × 7.5 for coal mining is studied in this paper. A 3D physical model for the fan´s flow passage is established. In order to get a more accurate 3D model for the two-stage impellers, the point clouds of the two-stage impellers are obtained using a 3D infrared scanner. The boundary conditions and assumed conditions for solving the air pressure on the blade surfaces are given. Based on the 3D physical mode and the boundary conditions, the air pressure distribution on blades surface when the two-stage impellers run at four different speed ratios is calculated. Based on the air pressure on blades, the deformations of the two-stage impellers are calculated and analyzed. The relationship between impellers deformation and rotating speed are gotten. Moreover, the maximum deformation quantities of the impellers are obtained as well. The results provide a necessary basis for the safe operation of the contra-rotating fan.