Abstract: Flow simulation analysis was conducted to solve the turbulent noise of a closed inlet chamber multi-blade centrifugal fan when running, it has been found that the uneven flow state inside the fan especially impeller area is the main cause of subjective hearing noisy. Pre-rotating guide vane was targeted designed according to the flow characteristics of this kind of fan, the subjective sense of hearing has been confirmed to be significantly improved by experimental verification. Compared to the original plan, the air volume under same rotating speed was improved by 5%, the sound pressure level under same air volume was reduced by 0.4~0.5 decibel, and the flow uniformity was highly improved.

Key words: Multi-blade centrifugal fan, Closed inlet chamber, Pre-rotating guide vane, Subjective sense of hearing