Numerical Simulation and Experimental Study of Noise Reduction of Bladeless Fan Based on Acoustic Metamaterials

With the increasing demand for household appliances, people are putting forward higher requirements for their sound quality. In this paper, we apply the theory of acoustic metamaterials to a bladeless fan and propose a curly space-type acoustic metamaterial (CSAM) to optimize the sound quality while ensuring the airflow of the bladeless fan. The acoustic transmission loss of CSAM is calculated by numerical simulations. Based on the hybrid approach to calculating aerodynamic acoustics (CAA) to calculate the aerodynamic noise of the bladeless fan, the ICFD module of Actran is used to convert the CFD simulated data into sound field data. The internal flow field and sound field of the bladeless fan with or without CSAM are compared and analyzed. Finally, an experimental test is done to verify the noise reduction effect and air velocity change after adding CSAM. The analysis shows that the change in the air velocity of the bladeless fan by adding CSAM is not apparent, and the sound pressure level at the monitoring point is reduced. The experimental results show that the noise of the bladeless fan is reduced by 4.9 dB after adding CSAM, and the wind speed at the location of the monitoring point is increased by 0.08 m/s. Without affecting the air velocity, CSAM can change the intensity of the sound source inside the bladeless fan and effectively suppress the aerodynamic noise. It demonstrates the feasibility of acoustic metamaterials to reduce aerodynamic noise.