Research On Inner Flow Fields And Structural Optimization Of Multistage Centrifugal Fan

With the centrifugal fan are more and more widely used in many fields of nationaleconomy and social life, multi-stage centrifugal fan has become increasingly important,meanwhile, the performance of multi-stage centrifugal fan also puts forward higherrequirements because of technological development and social needs. High-parameter,high-performance and high reliability are the direction of the next multi-stage centrifugal fan.In order to design high-performance fan, its internal flow must be researched, and thuspropose concrete and effective improvement program. So far, however, rare domestic andforeign experts and scholars researched on the internal flow field and explored to improve theperformance of the multi-stage centrifugal fan, based on this, the subject relies on theadvantages of CFD technology, using engineering fluid mechanics commonly softwareFluent6.3as the main tool, the internal flow field of three centrifugal fan is researched, andthe ways and means to improve the fan efficiency are explored. The main work done in thispaper are as follows:1. The current research situation and development direction of the centrifugal fan at homeand abroad are introduced;2. The flow equations and turbulence equations of the internal flow in the three-stagecentrifugal fan are deduced and the methods to dispose the near-wall region and the discretemethod of basic equations are described;3. According to the assumptions of the three-stage centrifugal fan, the geometric model andgrid model are established, and solution parameters are setted by comparing, then the internalflow field is calculated;4. According to the numerical calculation results of the design condition, different speedsand different pipe outlet sizes, internal flow characteristics are analyzed and compared, thedefects of the internal flow are found, and the fan performance curves under differentconditions are obtained;5. The internal flow and performance of the three-stage centrifugal fan with different bladenumber combinations are analyzed and compared, according to this, the matching features ofthe number of impeller blades are researched, and the more efficient combination of thenumber of blades is found, which indicates that this idea is feasible to improve the efficiencyof the fan;6. The single-stage impeller of the original fan is modeled by using Cfturbo, and theperformance curves of the impeller are predicted, then the structure of the impeller is optimized by changing parameters, the performance of the optimized impeller is improved.