Study On Axial Non-uniform Optimization Design Of Multi-blade Centrifugal Fan Impeller

Multi-blade centrifugal fan has the advantages of high pressure coefficient,large flow coefficient,small size and little noise.It is widely used in national production and life.The internal flow of multi-blade centrifugal fan is very complex and the impeller inlet airflow along the axial distribution is not uniform because the diameter ratio and relative width of impeller are larger.Aiming at the characteristics of the non-uniform flow,the purpose of this paper is to design and study on the axial non-uniform impeller of which the inner radius is conventionally axial uniform by means of CFD,so as to perfect the separated flow around the impeller top plate part and make full use of the impeller middle and bottom part to greatly enhance the performance of the impeller.The main research works and conclusions are as follows:(1)Based on the bevel cutting design of the impeller,the design and research of the impeller of a prototype fan are studied to explore the influence of the beveling impeller on the aerodynamic performance and flow field distribution of the fan.It is found that the bevel cutting design of the original fan impeller can perfect the flow states of the impeller top plate part but can not make full use of the impeller middle and bottom part,so as to can not improve the aerodynamic performance of the fan.When the impeller bevel cutting designed,the inner diameter of the impeller top plate has a great influence on the aerodynamic performance of the fan.The unreasonable diameter of the impeller top plate can lead to the decrease of the aerodynamic performance of the fan.(2)The axial non-uniform design of the impeller is proposed,and the axial linear nonuniformity of the impeller is designed and studied.It is found that the impeller diameter determines the aerodynamic performance improvement potential of the beveling impeller,and the inner diameter of the impeller top plate has a great influence on the air flux of the beveling impeller.In the top and middle part of the impeller,the beveling impeller perfects the separation vortex in the blade passage and the eddy and back flow in the outlet of the impeller near the fan exit,so as to improve the air flow of the impeller top and middle part.(3)Based on the axial linear nonuniform impeller,the nonlinear design and research of the axial multi-section linear and axial spline curves of the prototype fan are carried out for the more full use of the impeller bottom part.It is found that the bevel design of the impeller bottom part can perfect the flow state in the blade passage and improve the air flux,but the effect is not obvious due to the influence of the built-in motor.The axial spline curve impeller model compared with the axial multi-section linear impeller model,the aerodynamic performance of the fan is not improved obviously.