Research The Performance And Flow Characteristics Of Asymmetric Dual-rotor Small Axial Fan

Appliances cooling systems require a small radiator fan to dissipate heat. Domesticmanufacturers of cooling fans which have low energy efficiency often simply copy others’ fanslead to fans’ poor running, not running smoothly, a waste of resources. So how to improve thesmall axial fans’ work efficiency has become an urgent matter. In this paper, asymmetricdual-rotor small axial fan is as object of study. It analyzes the impact of structural parameters onthe fans’ static characteristics, internal flow and noise by using numerical simulation of flow fieldcalculation. We make the blades’ skew and sweep angle as variables, to fan static pressureefficiency maximize by using response surface optimization. Optimal parameters and theoptimization model are put forward, and the optimization model to do experiment. Its maincontents are as follows:Different hub-ratio of dual-rotor fans are regarded as research object. Using numericalsimulation method analyzes the effect of hub-ratio on the fans’ static characteristics and internalflow. The results show that it can improve fans’ static characteristics, ventilation area anddischarge capacity by making down one of the fans’ hub-ratio during the limit of wheel size.We establish response surface model which the blades’ skew and sweep angle asindependent variables and the efficiency of the fan as dependent variable. The results of theregression analysis show that the change of blades’ skew and sweep angles can increaseefficiency effectively. The most important factor on fans’ efficiency is the blades’ skew angle,followed by sweep angle. Finally, the optimization condition of the most efficient fans and thestructure of the fan’s model are provided.Analysis on internal flow characteristics of the original model and the optimization model,the result shows that the blade pressure distribution along the blade height of the optimizationmodel is more uniform than the original model. The differential pressure between suction surfaceand pressure surface, axial pressure gradient and power capability of the optimization model arelarger than original model. The experimental study of static characteristics found that thepressure rise of Small dual-rotor axial fan is two times higher than small single-rotor axial fan.Contrast the noise of the original model and the optimization model, the result shows that the vortex-shedding strength on tip clearance and vortex magnitude on the trailing edge of theblade of the optimization model are both smaller than the original model.The noise of theoptimization model is lower than the original model. At the fundamental frequency, the soundpressure level on the tip clearance of the optimization fan reduces2.5dB than the original fan.