Discrete tonal noise investigation of the cross-flow fan with block-staggered impellers

Abstract

Experimental and numerical studies have been carried out to investigate the detailed effects of discrete tonal noise on a cross-flow fan (CFF) with block-staggered impellers in an air-conditioner indoor unit. First, the aeroacoustic and aerodynamic performance of the CFF with different impellers was obtained through experiments. Then the two-dimensional (2D) computational fluid dynamics (CFD) model was established to solve the pressure fluctuations on noise-generating surfaces. The flow character and noise sources are discussed on the basis of the CFD simulation results. The noise properties generated by different block-staggered impellers are predicted by using the Ffowcs Williams and Hawkings equations from the surface pressure fluctuations provided by the CFD simulations, and the relations between noise property and stagger angle have been discussed. The influence of the spanwise length of a CFF has also been considered during the noise calculation, and the relative results are compared with the traditional pure 2D model. The predicted results are evaluated by comparisons with the experimental data both in time and frequency domains.

Keywords

air-conditioner cross-flow fan stagger angle noise prediction aeroacoustic

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