Attività

The performance of a centrifugal fan with enlarged impeller

The influence of enlarged impeller in unchanged volute on G4-73 type centrifugal fan performance is investigated in this paper. Comparisons are conducted between the fan

with original impeller and two larger impellers with the increments in impeller outlet diameter of 5% and 10% respectively in

the numerical and experimental investigations. The internal characteristics are obtained by the numerical simulation, which

indicate there is more volute loss in the fan with larger impeller. Experiment results show that the flow rate, total

pressure rise, shaft power and sound pressure level have increased, while the efficiency have decreased when the fan operates

with larger impeller. Variation equations on the performance of the operation points for the fan with enlarged impellers are

suggested. Comparisons between experiment results and the trimming laws show that the trimming laws for usual situation can

predict the performance of the enlarged fan impeller with less error for higher flow rate, although the situation of

application is not in agreement. The noise frequency analysis shows that higher noise level with the larger impeller fan is

caused by the reduced impeller–volute gap.