Abstract
In the present paper the attention is focused on the relation between fan noise and velocity fluctuations of tip leakage flow around rotor blade of a low pressure axial flow fan. We measure time fluctuating velocity near the rotor tip around the rotor blades by using a hot-wire sensor from a relative frame of reference fixed to the rotor blades. As the results, it is clear that the velocity fluctuation due to tip leakage flow has weak periodicity and the heap portion appeared in its spectrum. If the flow rate was lower than the design condition, the tip leakage flow became to attach to the following blade and the sound pressure level was increased. At the maximum pressure operating point, the correlation between the velocity fluctuation due to tip leakage flow and acoustic pressure were increased.
