| In order to reduce noise and improve the aerodynamic performance of air conditioner outdoor unit, study on aeroacoustics and flow characteristics of semi-open low pressure axial flow has become one of research focus. In this paper, semi-open axial flow fan with shroud, which is included in outdoor units of commercial air conditioner is investigated. The three-dimensional turbulent flow field of the axial flow fan with uniform inflow is analyzed by CFD simulation, especially the formation and development process of tip vortex and the flow field interference of parallel axial fan are studied. Then a hybrid method coupling near-field CFD calculation plus the application of an integral nonhomogeneous FW-H function for the far-field is adopted to predict the sound pressure level and the noise spectrum for both single and parallel axial fans. The distribution of sound source, the pressure pulsation at sound source and the characteristics of noise spectrum with different surfaces as sound source are discussed, and the impact on aeroacoustics under the condition that parallel fans with different speed and different blade numbers have been researched. This paper provided the theoretical foundation for optimization design, reducing noise and improving the aeroacoustics of the semi-open low pressure axial fan. |
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