| Due to its high output pressure, the forward curved centrifugal fan is widely used in the field of high-pressure forced ventilation and material transportation. However the existing forward curved centrifugal fans still have the defects of low efficiency, high noise and narrow operating conditions, hence it is difficult to meet the requirements of modern environmental protection and energy saving. In this paper, the numerical simulation method is studied to simulate the centrifugal fan in order to improve the aerodynamic performance.In this paper,the 9-26-4A centrifugal fan is chosen as the research object, based on the results of CFD numerical simulation calculation, multi-objective optimization design method is used to modify the structure of impeller on multi-points, to improve the efficiency of centrifugal fan under different condition and broaden the operating ranges of the high efficiency area; After the completion of the impeller structure optimization,aiming at volute tongue structure which has great influence on the noise of centrifugal fan,using inclined volute tongue to analyze the flow characteristic in the tongue area and the noise of centrifugal fan.Based on the numerical simulation method, the aerodynamic performance of the centrifugal fan is predicted in whole flow range. And the numerical calculation method,grid number and the boundary condition are tested and verified, which shows that the numerical simulation is reliable.Based on the inner flow analysis of the prototype centrifugal fans under different working conditions, the geometric parameters of the impeller structure which have great influence on the aerodynamic performance are obtained: blade inlet and outlet installation angle, Blade bending curvature and blade width. Taking the above four parameters as design variables, the weighted efficiency and total pressure of multiple working conditions as the optimization goal, the space sample points are obtained by Optimal Latin hypercubedesign and the target weight ratio is determined by the super transitive approximate method. Using approximate model and multi-objective genetic algorithm to optimize the design of multiple targets and multiple working conditions for centrifugal fans. The results show that the optimized model is beneficial to improve the aerodynamic performance of the fan.After the completion of the impeller structure optimization,the aerodynamic performance and noise of centrifugal fan are predicted by CFD and visual lab acoustics software under three different inclined volute tongue structure. The results indicated that Inclined volute tongue is beneficial to reduce the pressure fluctuation of the tongue surface and is conducive to reducing noise of the centrifugal fan. |
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