Abstract: Most of the inside of window air conditioner use centrifugal fan blade for air supply. The current noise is generally more than 60 dB due to the existing centrifugal fan blade profile and air duct structure. In this paper, in order to study the impact of centrifugal fan blade and air duct on noise, summarize the design method, and carry out simulation analysis and experimental research on fan blade profile and air duct. By studying the influence of the blade angle of the backward inclined centrifugal fan blade on the air volume and the influence of the duct cochlear tongue on the noise of the backward inclined centrifugal fan blade, the theoretical analysis and experimental research on the blade angle and the structural design of the duct cochlear tongue are carried out. Through experimental research, the influence of blades with different inclination angles on air volume and the influence of volute tongue shape on the noise of backward inclined centrifugal blades are obtained, which reduces the total noise of the whole machine by more than 3 dB and applies it to practical production, which provides a direction for subsequent blade shape optimization and air duct optimization.

Key words: Backward centrifugal fan blade, Noise reduction volute tongue, Air volume, Noise