In order to clarify the relationship between the aerodynamic noise and the flow regime around the rotating blade of a propeller fan operated at the maximum efficiency point and the off-design point, the characteristics of fans with different solidity impellers were analyzed experimentally. At the off-design point, the broadband noise of the high solidity fan was much larger than that of the low solidity fan because the relative velocity increased according to the solidity and the noise sources increased because of the number of blades. In the case of the low solidity fan, the broadband noise due to wake vortex shedding was generated at the off-design point in the low flow rate domain and the maximum efficiency point because the relative flow around the blade separated easily.
Cite this paper
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