Abstract: In order to improve the sound quality experience of fresh air, the fresh air module is taken as the research object, through the noise source identification and modal analysis methods, reinforcement ribs are set up on the non-contact surface of the cavity and a shunt cone is set in the cavity, so as to optimize the mode of the air cavity and the internal air flow organization, and improve the low-frequency radiated noise caused by the high-speed inflow impact. The verification results show that at the same speed, the fresh air volume is increased by 3 m³/h, avoiding the excitation frequency and the excitation peak value is reduced by more than 15 dB(A), which effectively improves the cavity sound of the fresh air module and improves the experience of indoor sound quality.

Key words: Fresh air conditioner, Airflow excitation, Vibration characteristics, Low-frequency noise