プロペラファンの翼端渦と周期的な空力騒音に関する研究

（羽根枚数の影響）

抄録

In order to discuss the major factor on the noise characteristics of a propeller fan, the influence of the blade numbers on the periodical fan noise generated due to the blade tip vortex is analyzed. The influence of the blade tip vortex on the fan noise is argued by the measured internal flow. For the analysis of the structure on the mean flow in the blade passage, the phase of the unsteady signal of the wake is locked by the trigger signal synchronized with the rotation signal. The noise generated from the tip vortex became 200 Hz even if the number of blades was different. We clarified experimentally that the periodical noise due to the blade tip vortex changed according to the scale of the tip vortex.