Study On Internal Flow And Performance Improvement Of Centrifugal Fan

Impeller is the most important part of centrifugal fans, at the same time, inlet nozzle has asignificant impact on the performance of the centrifugal fans. This paper mainly aims at theperformance improvement study of multiple centrifugal fans and unhoused centrifugal fans.Specifically this paper improves the structure of inlet nozzle and the type of the blade. Thepurpose is to improve the total pressure and efficiency of the whole system, to raise the staticpressure and efficiency of unhoused centrifugal fans and reduce the noise.This paper uses a multiple centrifugal fan as the research prototype, improving the casingbody and the inlet nozzle structure of multiple centrifugal fan, adopting numerical simulationmethod to study the performance of the whole system of improved model, analyzing the staticcharacteristics and internal flow characteristics of the whole system. The main contents are asfollows.First, this part uses the numerical simulation method to analyse the internal flow fieldstructure of the prototype and find the the major parts that affect the whole system performance.Second, this part uses the same method to analyse the static characteristics, pressuredistribution and velocity distribution of the whole system of the improved model and comparethose with the prototype’s.The results show that: proper structure of casing body and inlet nozzle can improve theinternal flow condition of multiple centrifugal fan, raise the total pressure of the whole system,and increase the operation efficiency. Total pressure of the improved model increases10.10%and efficiency improves4.71%in the condition of Q=7.7m3/min.The second part of this paper uses a unhoused centrifugal fan as the research prototype, andthen improves the impeller balde type to found the improved model. After that we compare theprototype with the improved model in static performance, efficiency and the sound pressure level.The main contents are as follows.First, this part completes the numerical simulation analysis of the prototype unhousedcentrifugal fan(SYW560) and the results is consistent with the experimental measurement results.So that the reliability of numerical simulation is verified. Through modifying blade shapes ofunhoused centrifugal fan, we have two improved models. And then obtain the static performancecurve and the efficiency curve using the numerical simulation method. Second, this part does the unsteady numerical simulation of improved models and analysesits internal flow field. Then compare its overall sound pressure level with the prototype’s.The results show that: appropriate impeller blade shapes can improve static characteristics,increase operational efficiency and reduce noise. On the design condition, total pressureincreases3.08%and efficiency improves3.67%.