Authors: Norimasa Shiomi Yoichi Kinoue Yingzi Jin Pin Liu Toshiaki Setoguchi
Publish Date: 2011/05/21
Volume: 20, Issue: 3, Pages: 218-
Abstract
In order to clarify the unsteady flow fields at low flowrate region with positive gradient on pressure — flowrate curve the experimental investigation was carried out at rotor inlet and outside of rotor blade tip without casing in a semiopened propeller fan using a hotwire anemometer A single Itype hotwire probe was used and the data obtained were processed by the use of phaselocked averaging ensemble averaging and FFT analyzing The flow fields at rotor inlet and outside of rotor blade tip were discussed mainly using the results from distributions of velocity fluctuations and power spectrum density It was found from these results that there are the two types of different periodical fluctuations and both of those frequencies were not the same of rotor rotating frequency RRF 15Hz One was observed at relatively high flowrate region at relatively downstream area in measurement and its frequency was approximately 7Hz 47 of RRF The other was observed at relatively low flowrate region at relatively upstream area in measurement and its frequency was approximately 10Hz 67 of RRF” As the velocity fluctuations with the flow fields are rapidly increased by the former fluctuation it is thought that its fluctuation is the trigger of blade stall
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