Prediction of Flowfield and Acoustic Signature of a Split-type Air Conditioner

The fan is one of the major noise sources of an air conditioner. Because of the presence of other components in the fan assembly, such as the bell-mouth, outlet grille and compressor chamber, the ingested and discharged flow fields around the fan impellers are distinctly different from those in a free field. Therefore, the noise generation mechanisms become much more difficult to analyze and model. This paper concentrates on understanding the generation mechanism and evaluating the noise in the fan system of a split-type air conditioner. Acoustic measurements were performed to analyze noise characteristics and to evaluate the effect of each component. Large eddy simulation was applied to predict detailed flow fields. Accordingly, unsteady flow data were fed into an acoustic analogy model to evaluate radiated sound. The predicted discrete frequency noise and sound spectrum proved that computation is accurate compared to measurement.