Abstract: With the higher requirements of the majority of users for the comfort of air conditioning, the noise problem of air conditioning outdoor unit has become increasingly concerned, and the research on noise problem is also the key to improving the performance index of air conditioning. Therefore, with the goal of reducing the operating noise value of the axial fan of the air conditioner, from the point of weakening the vortex of the blade tip and the leakage vortex of the blade top on the surface of the fan, on the basis of the existing axial fan, combined with the shape of the wings in the biological world, a sawtooth bionic fan structure with blade top was designed, and the original and bionic fans were simulated by using the STAR-CCM simulation tool. The simulation results show that the broadband noise of the bionic fan is reduced by about 2~4 dB(A) compared with the original model, and the noise reduction mechanism of the gradual bionic sawtooth at the top of the blade is revealed in multiple dimensions. The analysis shows that the designed biomimetic structure effectively changes the strength and development trajectory of the blade tip vortex and the blade tip leakage vortex and has a positive impact on the noise reduction of axial fans.

Key words: Air conditioner, Axial fan noise, Blade top vortex intensity, Sawtooth bionic fan