Abstract
In order to clarify the inlet flow fields of a semi-opened propeller fan with bellmouth at low flow-rate region, especially
the flow fields outside of blade tip, the experimental investigation was carried out using hot-wire anemometer. The axial
and tangential velocity component including the radial velocity component were measured using a single I-type hot-wire
probe. FFT analysis was done to search the periodical fluctuation with frequency different from the one for rotor rotating.
And, the distributions of velocity fluctuations on meridional plane were shown to obtain the flow structure at low flow-rate.
As a result, it was confirmed that two types of periodical fluctuations without rotor rotating frequency, which are similar to
rotating stall, occur. One has a frequency of approximately 7 Hz at φ=0.210 near rear portion of open area, and the other has
as frequency of 10 Hz at φ=0.180 near front portion of open area. It is also found that the flow condition largely changes
near these flow-rates.
