Correlation between Aerodynamic Noise and Velocity Fluctuation of Tip Leakage Flow of Axial Flow Fan

Hiromitsu Hamakawa, Masatomo Shiotsuki, Takaaki Adachi, Eru Kurihara

Department of Mechanical Engineering, Oita University, Oita, Japan.

DOI: 10.4236/ojfd.2012.24A026                

Abstract

In the present paper the attention is focused on correlation between fan noise and velocity fluctuations of tip leakage vortex around rotor blade of a low pressure axial flow fan at the maximum pressure operating point. We measured time fluctuating velocity near the rotor tip around the rotor blades by using a hot-wire sensor from a relative flame of refer- ence fixed to the rotor blades. As the results, it is clear that the velocity fluctuation due to tip leakage vortex has weak periodicity and the hump portion appeared in its spectrum. If the flow rate was lower than the design condition, the tip leakage flow became to attach to the following blade and the sound pressure level at frequency of velocity fluctuation of this flow was increased. The correlation measurements between the velocity fluctuation of tip leakage flow and the aerodynamic noise were made using a rotating hot-wire sensor near the rotor tip in the rotating frame. The correlation between the velocity fluctuation due to tip leakage flow and acoustic pressure were increased due to generation of weak acoustic resonance at the maximum pressure operating point.

Keywords

Fan; Noise; Tip Leakage Flow; Relative Flow Measurement; Correlation Measurement; Acoustic Resonance

Conflicts of Interest

The authors declare no conflicts of interest.

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