Abstract: Based on our study of controlling the aeroacoustic noise of the cross flow fans using porous stabilizers, this paper studies the characteristics of the unsteady flow field in the fan using dynamic pressure measurements combined with large eddy simulation. The measured pressure signals show that the porous stabilizers are helpful to reduce the amplitude of fluctuation, so the noise of the cross flow fan is attenuated. The dynamics of vortical motions are analyzed by large eddy simulation. The computed pressure fluctuations are in good agreement with the experiments. A modification of the Powell’s vortex sound equation is proposed for considering the effects of porous media on the generation of flow induced sound.