Finite Element Structure Analysis And Optimization Design For 9-19-10D Centrifugal Fan Impeller

The centrifugal fan is a widely used general machinery in many industries such as chemical engineering and mining.With the rapid development of the economy and the popularity of modern equipment, the long-time safe operation of the fans becomes an important subject. At the moment, the fan industry is developing in the direction of high speed, large size, high power and low noise. All the changes above would create problems in the design, manufacturing and the use of the fans, including the higher difficulty in strength checking.. As a part with the most serious load-carrying condition in the fan, impeller’s safe operation is the assurance of reliability of the fan machine. So it is very necessary to check the strength and do modal analysis for the impeller.Firstly, traditional strength calculation theory was used to check the strength.After the calculation, it is got that the highest stress is 108 MPa and the position is the entrance of the vane.The material to make the impeller is Q235 and its allowable stress is 175 MPa. So the highest stresses are meet the strength requirements.Then the FEM software ANSYS was used to check the strength of the impeller. A 3D model based on the design paper was built. The model was made of areas. Shell elements were used to build a FEM model and then the contiguous nodes of the vanes and the discs were coupled. It can be resulted from the displacement nephograms and stress nephograms that the displacements are small enough and can meet the requirements while the highest stress,105.9MPa in the exit of the vane, is slightly high. The highest stress in the entrance of the vane is about 70 MPa. And stress concentration exists in the junction of the vanes and discs.The vane root should be strengthened. So two projects were got to strength the vane root. From the results, it can be got that all the two projects can reduce the stress concentration and increase the strength. However, the second subject’s highest stress is 33% lower and the highest stress in the entrance of the vane is 40 MPa lower than the un-optimized one. And it has a structure with higher strength and lighter weight than the first one. So the second subject is more excellent. The FEM’s advantages are obvious that it can find the stress concentration positions, and its results are more visual and more accurate than the traditional theory method.Based on the structure optimization, modal analysis was taken on the impeller. And the first six natural frequencies and modes of vibration were got.Then the natural modes of vibration were translated to corresponding rotate speeds. After contrasting them with the working rotate speed of the impeller, it can be found that the impeller will not resonate.This paper checked the strength of the impeller using traditional theory method and ANSYS software. Then its structure was optimized and modal analysis was done. These can improve the reliability of the fan and have significance to other impellers in strength checking and structure design.