Aerodynamic optimization of forward-curved blade centrifugal fan characterized by inclining bionic volute tongue

The profile and axial designs of a volute tongue have great influences on the internal flow conditions and aerodynamic performance of a forward-curved blade centrifugal fan. In order to achieve a high quality of internal flow fields and fan aerodynamic performance, we propose an inclined bionic volute tongue (IBVT) described with rotation angle and scale coefficient at the front and back walls of the volute, which varies the profile of the volute tongue and the distance between the impeller and the volute tongue in the axial direction. Meanwhile, an adaptive pseudo expected improvement matrix (APEIM) parallel multi-objective efficient global optimization (EGO) algorithm is developed by introducing a flexible number of added points for each iteration of optimization on account of the optimization problem itself. On this basis, IBVT is optimized to maximize the fan aerodynamic performance in terms of total pressure efficiency and static pressure rise by virtue of numerical simulation. The results show that the developed APEIM parallel multi-objective EGO algorithm is capable of accurately and efficiently finding the Pareto front solutions. IBVT is considered to have the effectiveness of aerodynamic performance improvement for a forward-curved blade centrifugal fan. Within the fan with IBVT, the flow fields in the axial direction become more uniform with the dimension reduction of the inactive zone around the front span. The impeller-volute tongue interaction is greatly improved with the decreases of reversed and recirculated flow coefficients. IBVT also benefits the reduction of flow losses in the volute. By adopting the analysis of variance (ANOVA), the aerodynamic performance of the fan is highly affected by the rotation angle and scale coefficient of IBVT at the front wall of the volute. This work is helpful to guide the design of the volute tongue for a forward-curved blade centrifugal fan.