Abstract
In order to clarify the inlet flow field of a semi-open axial fan with bellmouth at low flow-rate region, 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. The data were processed using a phase-locked averaging technique. Those were also processed using a FFT analyzing. As a result, it was confirmed that there was a radial inflow through the blade tip into the blade passage at non-stall flow-rate condition. However, its radial inflow disappeared near stall flow-rate condition because of strongly tangential flow covering with the blade tip. It was also found that the flow pattern similar to rotating stall existed at its flow-rate condition by means of the results of FFT analyzing.
