Design of volute shape of centrifugal fans

This work addresses the issues of decreased efficiency and static pressures of a centrifugal fan under variable working conditions (VWCs). A design method for the volute radius with flow-correcting coefficients and an area factor was proposed. The model of the design method was solved using genetic algorithms in MATLAB. The volute was designed for two cases: with area constraints and without area constraints. Computational fluid dynamics was used in the numerical simulations of the original fan and the two others with modified volute under VWCs, and corresponding performance curves were obtained. The internal flow fields of the three types of fan volutes were analysed for the cases under 40%, 100%, and 130% loads. The results indicate that the efficiency and static pressure of the two designed fans were improved under VWCs. The backwash at the outlet tongue, volute outlet static pressure fluctuation, and the swirl effects inside the volute were all reduced. The volute fan with area constraints exhibited the best performance under VWCs.