3-D CFD Analysis Of The Flow Field Inside A Centrifugal Fan

The Centrifugal fan is of great importance in modern industry.Due to its low energy consumption,high rotational speed,high volumetric efficiency and its ability to deliver clean air and other advantages,the centrifugal fan is being used in many Chemical,Electrical and architectural areas to dispense and exchange air and other gases,and to exhaust smoke and lower temperatures and to deal with Pollution.Traditionally,The centrifugal fan is designed based on the results of experiments.However,due to the high cost and low efficiency of running those experiments,the design phase of the centrifugal fan takes longer to complete.Therefore,minimizing the time and cost of the design of the centrifugal fan has become a trend.With the current developments in computer technology,the use of numerical simulation to aid with the design process has gained extreme popularity.The Centrifugal fan is the object of interest for this research.The "unified design method" was used to design a forward curved,radial tipped Centrifugal fan.On this basis,Ansys CFD software components(ICEM,FLUENT,CFD-POST)were utilized to run 3-dimensional simulations on the designed fan in order to obtain its total pressure and total pressure efficiency,obtain flow field details and analyze factors that affect the centrifugal fan's performance.The conclusions of this research can be summarized into:(1)The internal flow field's energy transfer was analyzed,showing high and low pressure regions across the impeller.The energy transfer from the impeller to the fluid can also be confirmed from the pressure and velocity distribution contours.(2)Jet and wake regions were observed near the volute tongue.Back flow and pressure pulsation phenomena were also observed near the volute tongue region.Therefore,Volute design is crucial for avoiding backflow.(3)When the impeller is at the middle of the casing,static pressure across the fan rose by 57.24%.But,in comparison,exit velocity of the fan showed obvious increase when the impeller was fixed to the rear plate of the casing.(4)When the casing width was decreased by 30%,the exit velocity increased by 72.9% and its static pressure dropped by 9.51%.(5)The increase in the number of blades leads to balancing the relative velocity within the blade passages.Therefore,wake regions are decreased.This leads to decreasing the noise created by wake regions.Wake regions are one of the major contributors to losses in centrifugal fans.However,increasing the number of blades will further deteriorate the fan's performance.