# Study of the Noise Reduction Mechanism of Bionic Circular Arch Structures on the Blades of a High-Volumetric-Airflow Axial Flow Fan

## TL;DR

This study introduces a bionic circular arch structure on fan blades to reduce noise, showing significant noise reduction in key frequency ranges.

## Contribution

A novel bionic circular arch design is proposed for axial flow fans to reduce aeroacoustic noise more effectively than existing bionic structures.

## Key findings

- The bionic design reduces total sound pressure level by approximately 2.5 dB.
- Noise reduction reaches up to 6.6 dB in the human-sensitive frequency range of 1000–3000 Hz.
- The design mitigates noise source intensity at the blade tip and reduces boundary layer disturbances.

## Abstract

While bionic sawtooth and wave structures effectively reduce aerodynamic noise on fixed airfoils, their efficacy on rotating fans is often limited. Inspired by the protrusion structures of dragonfly wings and the gentle circular arches of manta rays, this study proposes a novel bionic circular arch structure to suppress aeroacoustic noise in axial flow fans. Numerical simulations were validated against experimental data from a standard fan, showing a sound pressure level (SPL) deviation within 3 dB at the first blade passing frequency (BPF), confirming calculation accuracy. The results indicate that the bionic design reduces the total SPL by approximately 2.5 dB. Notably, in the human-sensitive frequency range of 1000–3000 Hz, noise reduction reaches up to 6.6 dB at the upstream monitoring point. Analysis of Root Mean Square (RMS) fluctuating pressure and Fourier transforms reveals that the bionic structure significantly mitigates noise source intensity at the blade tip. This design effectively reduces pressure disturbances at the first BPF and shrinks the high-intensity disturbance region of the boundary layer compared to the prototype.