抄録
In order to clarify the relation between the discrete frequency noise of the propeller fan and the circular flow formed in the wake, the characteristics of the propeller fans were analyzed by the measurement of the flow and the CFD. The absolute velocity in the main flow domain of the meridional plane in the wake of the propeller fan became 30 m/s while the velocity in the inclined plane was decreased to 25 m/s. The velocity fluctuations on the vertical plane in the wake were weakened at the diagonal line by the velocity deformation formed to the circumferential direction around the impeller. Then the circular wake formed in the propeller fan was broken by the velocity deformation. It is considered that the discrete frequency noise of the propeller fan in the second harmonics became large since the fourteen dynamic rotors and the pseudo four stators made by the broken circular wake resonated.
