Abstract: As a core influencing factor of air volume and noise for the indoor unit of duct air conditioners, the centrifugal fan is such that the former is a key indicator for measuring the performance of duct air conditioners, and the latter is directly related to the user experience. Taking a certain type of duct air conditioner as the research object, systematically explores the matching mechanism between the height of the centrifugal fan for duct air conditioners and the size of the air inlet under the condition of a fixed air inlet size through simulation and experimental verification of multiple groups of different fan height parameters, so as to extract the optimization rules for the fan height applicable to engineering design. The study shows that when simply aiming at maximizing the air volume, there is a theoretical optimal proportional relationship between the fan height and the air inlet size; however, when considering the noise control requirements simultaneously, it is necessary to suppress the generation of large-scale eddies in the casing through structural optimization, and at this time, the optimal matching parameters will be redefined based on the aerodynamic-noise coupling characteristics.

Key words: Centrifugal fan, Numerical simulation, Experimental testing, Vortex, Diffuser separation vortex