Abstract: Detached eddy simulation (DES) is employed to simulate the near wake field and vortical characteristics for a ducted propeller under design condition. Spalart & Allmaras model is selected to satisfy the Navier-Stokes equations. Unsteady sliding mesh technique and hybird-grid have been used in the hydrodynamic performance simulation. Based on the analysis of the transient wake field and wake vortex structure, it is found that in the near wake flow field, continuous vortex structures are distributed near the propeller radius region, and the axial velocity is larger in the wake field than that in freestream. The vortex system is composed of shear-layer vortex of the duct, blade vortex system and hub vortex. The blade vortex system contains the tip vortex, root vortex, hub vortex and the S shape secondary vortex, which are induced between two adjacent tip vorteces. There exists complex interference between multiple vortices, which lead to the merging, distortions and breakdown of wake vortex morphology, and gradually diffuse in the downstream.

Key words: vortex morphology, ducted propeller, detached eddy simulation (DES), secondary vortex