Abstract
Three-dimensional structure and unsteady nature of vortical flow fields in a half-ducted propeller fan have been investigated by a detached eddy simulation (DES) based on k-ω two-equation turbulence model. To elucidate the complex vortical flow phenomena, vortex structures were identified by the critical point theory, and limiting streamlines visualized by a line integral convolution (LIC). Sound pressure levels induced by each flow structure were predicted by Lighthill's acoustic analogy using the pressure data on the solid surfaces. It is found that the high pressure fluctuation on the shroud surface, which is caused by the rotating interaction of the blade tip loading and tip vortex with the shroud, play a major role in characteristics of the half-ducted propeller fan noise.
