Noise suppression is of importance for jet engines, and acoustic panels are set in the fan duct in order to reduce the noise emission from the fan component. However, it is apparent that duct loss increases due to the acoustic panels because of the rough surface. Therefore, we have to develop a new acoustic panel that can realize large noise suppression and low duct loss. There have been a few numerical studies on the fan duct with acoustic panels, since Mach numbers in the main stream and inside the panel cavity are largely different and thus ordinary CFD solver for a compressible flow cannot be adopted. In the present study, we employed an all speed Roe scheme to reproduce the flow field with large Mach number difference. Visualizing the numerical results, we investigated the flow field around the acoustic panel hole, the duct loss, and the influence of the number of panel holes.
