Research On Influencing Factors About Small Axial Flow Fan’s Performance And Noise

With the development of miniaturization and higher performance of electronic products, thecalorific capacity of electronic parts in work is increasing. The problem of cooling in the limitedspace becomes the bottleneck for the development of many electronic products. For this, thesmall axial flow fan is the first choice of cooling for its ventilation, small size and low cost. So, itis significant to design the small axial flow fan with higher performance and low noise.The models RF24S9225H (model No.1) and KDE2406PHV1-A (model No.2) from SunonCompany are the prototype fans to study in this paper. The small axial flow fans with toothshaped trailing edge and with blade perforated are separately designed based on model No.1andthe small axial flow fans with different tip clearance are designed based on model No.2. Themodel No.1, model No.2and the improved models are simulated by using the CFD software andthe model No.1is also experimented, and then, the static performance, aerodynamic performanceand internal flow field are obtained. What’s more, the influence of tooth shaped trailing edge,blade perforated and tip clearance on the small axial flow fans is studied, from which the toothshaped trailing edge has no effect on static performance but the noise decreases about10dB.Blade perforated also has no effect on static performance, but the noise has reduced. When thetip clearance is1.5mm, the static performance is worse and when the tip clearance is1.0mm, thestatic performance is better but the sound pressure level is the highest, when the tip clearance is0.75mm, the sound pressure level is the lowest.In this paper, seven small axial flow fan models’ internal flow filed are analyzed. Thestreamline and distribution of turbulence intensity on meridional plane, acoustic power on thesurface of rotor of improved models are compared with the prototype fans’. Numerical resultsshow that the acoustic power of the small axial flow fan with tooth shaped trailing edge isweaken, the turbulence intensity in the exit area of the small axial flow fan with blade perforated,with the increasing of tip clearance, the vortexes in the exit area is enlarging.Influences of aerodynamic performance by different blade shape and tip clearance are discussed. Results indicate that the small axial flow fans with tooth shaped trailing edge and withblade perforated reduce noise effectively and the small axial flow fan with shaped trailing edge isbetter, the whole performance is better when the tip clearance is0.75mm.