Prediction and measurement of axial flow fan aerodynamic and aeroacoustic performance in a split-type air-conditioner outdoor unit

The study has focused on outdoor unit noise reduction by fan geometry modification with the refined numerical and experimental approaches. The outlet louver, electric motor and its support are included to refine the flow and acoustic model and a hybrid method incorporating CFD and CAA is used to predict the noise behavior. The fan performance curve is well-predicted; the moderate acoustic power is obtained on the outlet louver, motor support and motor exhibiting a significant contribution to overall noise behavior. The aeroacoustic test is conducted in an anechoic chamber and the obtained results are compared with the semi-anechoic chamber ones, and the unremarkable differences are produced, which indicate the ground floor being of some influence. Both modified fan geometries are effective to reduce the noise but the flanging outer-edge blade is more effective. The noise directivities of three geometry fans are investigated both numerically and experimentally and the produced asymmetric characteristics are analyzed.

► The refined numerical approach permits better prediction of fan performance and acoustic behavior.
► Unremarkable differences are produced in measured results with semi-anechoic and anechoic chambers.
► Modified fan geometry is effective for noise reduction.
► Asymmetric OASPLA distribution is produced both numerically and experimentally.