ABSTRACT Currently, domestic and abroad scholars put more attention on contra-rotating dual-rotor axial fan. But there is less scholars study on asymmetric dual-rotor small axial fan, which is one of the contra-rotating dual-rotor axial fans. Like axial fan, many factors have influence on the performance of the asymmetric dual-rotor small axial flow fan, such as the wheel hub ratio, blade shape, blade number, stagger angle and the tip clearance. Because wheel hub ratio has great impact on the performance of the fan, we choose the size of wheel hub ratio as a variable factor to study the model change. There is a different wheel hub ratio between front stage impeller and rear stage of asymmetric dual-rotor small axial fan, so it is very beneficial to select the greater wind area that the fan area of external diameter minuses the area occupied by the blades and the hub as front stage impeller. In this paper, the hub-ratio of front stage impeller is 0.72, and that of rear stage is 0.72, 0.67 and 0.62 respectively along with the front stage impeller. Three kinds of models with different hub ratio of rear stage are simulated using the CFD software and the static characteristics are obtained. Based on the experimental test results, the internal flow field of the asymmetric dual-rotor small axial fan is analyzed in detail, the impact trends of different hub-ratio on the performance of asymmetric dual-rotor small axial fan are obtained and the argument of structure optimization for dual-rotor small axial fan is provided.
Cite this paper
Y. Wu, Y. Jin, Y. Jin, Y. Wang and L. Zhang, "Effect of Hub-Ratio on Performance of Asymmetric Dual-Rotor Small Axial Fan," Open Journal of Fluid Dynamics, Vol. 3 No. 2, 2013, pp. 81-84. doi: 10.4236/ojfd.2013.32A013.
 Y. Kodama, “Experimental Study on the Characteristics of Fluid Dynamics and Notice of a Counter-Rotating Fan (1st Report, Effects of the Supporter Shape of the Electric Motor and the Distance between Two Rotors on the Characteristics),” The Japan Society of Mechanical Engineers, Vol. 60, No. 576, 1994, pp. 144-151.
 Y. Kodama, “Experimental Study on the Characteristics of Fluid Dynamics and Noise of a Counter-Rotating Fan (2nd Report, Effects of the Combination of the Number of Two Rotor Blades, the Solidity and the Tip Clearance),” The Japan Society of Mechanical Engineers, Vol. 60, No. 576, 1994, pp. 152-159.
 Y. Okabe, “On the Internal Flow of Contra-Rotating Small-Sized Axial Fan,” The Japan Society of Mechanical Engineers, Vol. 48, No. 105, 2009, pp. 395-396.
 P. Liu, “Effects of Rotor Structure on Performance of Small Size Axial Flow Fans,” Zhejiang Sci-Tec University, Hangzhou, 2011, pp. 37-47.
 Q. Y. Cui, “Study on Hub Ratio Optimization Design of Counter-Rotating Axial Flow Fan,” Compressor Blower & Fan Technology, No. 6, 2006, pp. 5-7.
 Y. P. Jin, “Optimization Design for Skew and Sweep Parameters of Mine Contra-Rotating Axial Fan Two-Stage Blades,” Journal of China Coal Society, Vol. 10, No. 35, 2010, pp. 1754-1759.
 Y. J. Zhang, “Effects of Axial Gap on Contra-Rotating Mine Fan’s Performance,” Journal of China Coal Society, Vol. 36, No. 7, 2011, pp. 1217-1222.