Study on the High Efficiency Low Noise Centrifugal Fan for Vacuum Cleaner

摘要

The centrifugal fan of vacuum cleaner is the main source for aeroacoustic noise and energy loss. Due to the high rotating speed of the impeller and a small gap between the impeller outlet and the diffuser inlet, the centrifugal fan produces very high level noise at blade passing frequency (BPF) and its harmonic frequencies. In order to develop new high performance fan, numerical approach was introduced. The aeroacoustic characteristics and noise reduction method of a centrifugal fan for a bag-less vacuum cleaner were studied. In order to calculate the sound pressure caused by the interaction of highly rotating flows in the centrifugal fan, the unsteady flow field data is necessary. The unsteady flow field is calculated by the node based CFD method. The performance – pressure rise and efficiency – was also calculated from the CFD numerical method. Ffowcs-Williams and Hawkings equation with dipole source is used in aeroacoustic noise prediction. The air-bone noise generated by the strong flow interaction between the moving impeller and stationary diffuser vane is calculated and the dominant noise source was visualized. By changing the geometry of the impeller and diffuser, new high performance centrifugal fan was designed. As a result, the efficiency of new fan is increased by 7% and the noise is same level when it compare with conventional one.