Structural Optimization And Analysis Of Multi-blade Centrifugal Fan For Fresh Air Unit

Multi-blade centrifugal fans are an important part of fresh air unit for air-conditioning.As people’s demands and requirements for equipment increase,the overall performance of wind turbines is in urgent need of improvement.The numerical calculation method can optimize the design of the relevant structure of the multi-blade centrifugal fan with high efficiency,reduce the probability of fan failure,and improve the performance of the fan.In this paper,the finite element method is used to conduct the static analysis and modal analysis of the small-flow multi-blade impeller for small fresh air unit,the vibration characteristics of the impeller are obtained and the impeller structure is further optimized to prevent mechanical damage.On the other hand,the CFD technology is used to calculate the large-flow multi-blade fan for big fresh air unit,and the calculation results are verified by experiments.At the same time,the orthogonal design method is used to optimize the impeller parameters,after improving the structure of the impeller,the fan container structure is optimized,and the influence of the volute position and the inlet baffle on the performance of the fan is studied.The finite element analysis of the small-flow multi-blade impeller results in the stress distribution of the impeller and the first ten-order impeller mode.The results show that the impeller satisfies the strength,but part of the natural frequency of the impeller is too close to the excitation frequency,The impeller has a resonance risk.By optimizing the mid-disk structure,the natural frequency avoids the excitation frequency and effectively reduces the resonance risk.In addition,the calculation results of the large-flow multi-blade fan are not much different from the experiment.At the same time,the optimization scheme of the impeller parameters can be obtained by orthogonal design.The results show that the optimization scheme can effectively improve the total pressure and efficiency of the fan in the full flow range.In addition,after the number of blades reached 60,the performance of the fan is tempered,and the number of blades is selected to meet the economic requirements.Finally,the simulation of different container structures is carried out to obtain the performance of the fan under different working conditions.The results show that optimizing the volute position and the inlet baffle can effectively improve the total pressure and efficiency of the fan under large flow conditions and improve the internal flow of the container.The situation has a limited impact on moderate flow conditions.