The performance of air fans is deteriorated for inlet airflow maldistribution. To solve this problem

by applying the advanced three dimensional flow field analysis software

the performance of a double-sided centrifugal air fan which is commonly used in power plants was numerically simulated

under conditions with different inlet airflows. The result indicates that

in practical operation

the inlet airflow distribution has great effect on the performance of the double-sided centrifugal air fans. When the inlet velocity is uniform or nearly uniform

the inlet airflow distribution is uniform

the vortex flow is small

and the fan efficiency is high. When the inlet velocity distribution is uneven

axial rotation of the air flow in different directions will occur at the impeller inlet

the vortex flow will increase

resulting in a poor fan performance.