抄録
A vortical flow in a half-ducted propeller fan has been investigated by a large eddy simulation (LES) using the subgrid-scale model of Smagorinsky. The simulation shows that the tip vortex plays a major role in unsteady behavior of the vortical flow in the propeller fan. The tip vortex grows nearly in the tangential direction, thus impinging on the pressure surface of the adjacent blade. The spiral-type breakdown of the tip vortex occurs near the midpitch, so that the tip vortex twists and turns violently with time. The sound pressure radiated from the fan rotor blade is dominated by the pressure fluctuation caused by the breakdown of the tip vortex.
