Numerical Investigation of the Aerodynamic and Aeroacoustic Characteristics of a Double-suction Centrifugal Fan under Different Operating Conditions

Centrifugal fans are widely used in the ventilation and domestic appliance industries. Their aerodynamic and aeroacoustic characteristics vary significantly in different application scenarios and operating conditions. This study applied a double-suction multiblade centrifugal fan to a range hood. The full threedimensional flow and acoustic field were calculated synchronously using direct computational aeroacoustics (CAA) based on the lattice Boltzmann method (LBM) to investigate the internal flow, aerodynamic noise, and acoustic source characteristics of the fan under different operating conditions. We focused on two typical operating conditions: the maximum volume flow rate and working volume flow rate. The accuracy of the numerical simulation was verified using experimental data measured from the performance test bench and the semianechoic chamber. The flow field results show that more than 70% of the airflow enters the volute from the main wind inlet; this asymmetric wind intake condition creates an asymmetric flow pattern inside the volute. Acoustic waves radiate to the far-field mainly through the inlet and outlet of the range hood. The propagation characteristics of a dipole source are not very obvious and the tonal noise associated with the blade passage frequency (BPF) is not significant. In addition to the acoustic sources identified in the impeller region, the volute tongue, and the gap between the impeller and the inlet nozzle, two other significant acoustic sources are identified in the outlet collector and inlet nozzle regions.