Air flow noise is an important parameter influencing the amenity of indoor environment

which is mainly caused by the cross flow fan in the indoor unit of air conditioners. The noise prediction method is presented by integrating the unsteady flow field simulation and aerodynamic noise model. The unsteady incompressible Navier-Stokes equation is solved with RNG k-ε turbulence model with a sliding mesh technique. The aeroacoustic pressure is calculated by Ffowcs-Williams and Hawkings equation. The unsteady pressure data

which is calculated from the unsteady flow field

is used as input data for the FWH equation. This method is applied to analyze the unsteady flow field and flow noise of the cross flow fan in the indoor unit

and the predicted sound pressure level and acoustic spectrum agree well with the measured data not only total noise but also broadband noise. These results show that this numerical method can be used as an effective tool for optimization of axial fans for compact design

large air volume and low noise.