In order to reduce the aerodynamic noise of the traditional blade-type axial fan and inspired by the owl wing profile and non-smooth edge structure
the thickness distribution at the 40% span of the long-eared owl with silent flight characteristics was extracted based on the medial camber line distribution of the prototype axial fan as a benchmark. Combined with the non-smooth structural features of the long-eared owl wing edges and coupled with a sinusoidal sawtooth structure at the trailing edge of the imitated owl blade
bionic reconstruction of the axial fan blade was performed and used in the modified blade design to reduce the noise of axial fans. Based on the numerical calculation results of the internal flow field of axial fan
the large eddy simulation(LES)combined with the FW-H sound analogy method developed by Ffowcs Williams and Hawkings was used to numerically simulate the sound field characteristics of the axial fan. The research results show that the overall noise reduction of the bionic coupled blade fan is 2 dB and the air volume is increased by 4.69% compared with the prototype fan. The internal flow field and sound field of the fan show that the bionic coupled blade makes the air flow transition from the suction surface to the pressure surface more smoothly
which not only improves the local impact of the air flow on the leading edge of the blade
but also reduces the leakage vortex strength at the tip clearance. In addition
the turbulence boundary layer generated by the bionic coupled blades and the degree of airflow pulsation and airflow unevenness caused by the wake vortex shedding are weakened
and both broadband noise and discrete noise are reduced in the low-mid frequency range. Therefore
the bionic coupled blade not only improves the local pressure pulsation at the leading edge of the blade
but also reduces the intensity of the sound source at the trailing edge serration and improves the trailing vortex distribution at the trailing edge of the blade.
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