Effects of bionic volute tongue bioinspired by leading edge of owl wing on aerodynamic performance and noise of multi-blade centrifugal fan

Bionic volute tongue bioinspired by the leading edge of owl wing, a new type of noise-reduction structure, is designed for multi-blade centrifugal fan. Adopting reverse engineering method, the section profile in the position of 40% spanwise of the wing of a long-eared owl, whose aerodynamic performance is relatively excellent, is extracted to restructure the bionic volute tongue. Numerical simulations are respectively conducted to investigate the aerodynamic performance and noise characteristics of the prototypical fan and the developed fan with the bionic volute tongue. Compared with the prototypical fan, the volume flow rate of the bionic fan is increased by 1.9 m³/min, while the noise is decreased by 1.6 dB and the efficiency is increased by 3.8%. The bionic volute tongue bioinspired by the leading edge of owl wing facilitates weakening the impact of the airflow to the volute tongue of multi-blade centrifugal fan, and the flow separation is suppressed effectively. Near the volute tongue, the adverse pressure gradient is reduced significantly, and the corresponding vortex's structure, distribution and intension are also changed.