Noise reduction and aerodynamic performance improvement of a multiblade centrifugal fan

Multiblade centrifugal fans are widely used in various fields. With the rapid increase in fan performance requirements, improving aerodynamic performance and reducing noise by modifying individual component parameters are no longer sufficient to meet the demands of actual engineering applications. In this work, a combined noise reduction scheme was adopted to reduce the noise level of the fan under different operating conditions while improving its aerodynamic performance. The three-dimensional unsteady flow and acoustic field of the fan were calculated simultaneously via direct computational aeroacoustics based on the lattice Boltzmann method. Experimental data from the performance test bench and the semianechoic chamber were used to validate the accuracy of the numerical simulation results. A curved-type outlet collector, a nonaxisymmetric inlet nozzle, and a variable inlet/outlet angle blade were designed on the basis of the identified acoustic sources. Different modified schemes provide varying benefits under different operating conditions, but their optimal combination not only reduces the noise of the fan but also improves its aerodynamic performance. The simulation and experimental results show that the total pressure efficiency is significantly improved at the same volume flow rate for both operating conditions and that the noise is reduced by 1.5 and 1.4 dBA. The articulation index improved by a maximum of 5.2%. This study provides a valuable reference for the design of multiblade centrifugal fans with wide operating conditions, high efficiency, and low noise.